Aluminium in Commercial Vehicles

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This guide will be of particular interest to design and process engineers, to repair and maintenance managersand more generally to anyone with an interest in the applications and development of aluminiumin road transport.Given the obvious limitations of a single volume, it has not been possible to deal with all aspects indetail. We have opted to present what we regard as the most up-to-date concepts and have indicatedthe most relevant standards which the reader can refer to for further information.

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ALUMINIUM
IN COMMERCIAL
VEHICLES
1
EUROPEAN ALUMINIUM ASSOCIATION
2
A lum inium in C om m ercial Vehicles has been com piled by the European A lum inium A ssociation in
answ er to the needs of m anufacturers and users of com m ercial vehicles and accessories. It is a com -
pendium of basic inform ation on such aspects of alum inium as:
•The reasons for using it
•The m ain rolled, extruded and cast alloys available to m anufacturers; their properties, m echanical
characteristics etc.
•The design and calculation of structures, fatigue and collision behaviour
•The joining of sem i-finished products: fabrication, w elding and other joining techniques
•The corrosion resistance of alum inium alloys under service conditions
•Surface treatm ent
•C leaning and repair
This guide w ill be of particular interest to design and process engineers, to repair and m aintenance m an-
agers and m ore generally to anyone w ith an interest in the applications and developm ent of alum inium
in road transport.
G iven the obvious lim itations of a single volum e, it has not been possible to deal w ith all aspects in
detail. W e have opted to present w hat w e regard as the m ost up-to-date concepts and have indicated
the m ost relevant standards w hich the reader can refer to for further inform ation.
The information in this publication is general in nature and is not intended for direct application
to specific technical or scientific projects. The European Aluminium Association cannot be held
liable for any damage, costs or expenses resulting from the use of the information in this
publication. For additional information please contact your aluminium supplier to be able to
discuss details directly with the relevant experts.
FOREWORD
3
EUROPEAN ALUMINIUM ASSOCIATION
I. FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
II. ALUMINIUM IN TRANSPORT . . . . . . . . . . . . . . . . 7
1. One century of aluminium in transport . . . . . . . . . . . . . . . . 8
2. Evolution of commercial vehicles . . . . . . . . . . . . . . . . . . . . 12
3. Aluminium applications and weight savings . . . . . . . . . . . 13
4. Today’s concerns . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
III. WHY USING ALUMINIUM . . . . . . . . . . . . . . . . . . 15
1. Short pay-back . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2. Aluminium performance properties . . . . . . . . . . . . . . . . . . 18
3. Environmental and social Benefits . . . . . . . . . . . . . . . . . . . 22
4. On the road… . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
IV. FREQUENTLY ASKED QUESTIONS . . . . . . . . . . 29
1. Aluminium . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2. Aluminium chassis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
3. Aluminium tippers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
4. Aluminium tankers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
V. ALUMINIUM ALLOYS
FOR COMMERCIAL VEHICLES . . . . . . . . . . . . . . 39
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2. International product designation . . . . . . . . . . . . . . . . . . . 41
3. Basic temper designations . . . . . . . . . . . . . . . . . . . . . . . . . 42
4. Subdivisions of H temper designations . . . . . . . . . . . . . . . 42
5. Subdivision of T temper designations . . . . . . . . . . . . . . . . 43
6. Typical alloys for commercial vehicles . . . . . . . . . . . . . . . . 44
7. Influence of temperature on mechanical properties . . . . 50
8. Influence of fabrication on the properties of the alloys . 52
9. List of standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
VI. DESIGN AND CALCULATION . . . . . . . . . . . . . . . 57
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
2. Possibilities with aluminium . . . . . . . . . . . . . . . . . . . . . . . . 58
3. Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4. Aluminium versus Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5. Limit state design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6. Serviceability limit state . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
7. Ultimate limit state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
8. Fatigue . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
9. Special design issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
C O N T E N T S
4
VII. FABRICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
2. Fabrication of products from plate . . . . . . . . . . . . . . . . . . 93
3. Fabrication of products from extrusions . . . . . . . . . . . . . . 98
4. Drilling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
5. Tapping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6. Deep Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
7. Spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
VIII. WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
2. TIG welding (Tungsten Inert Gas) . . . . . . . . . . . . . . . . . . . 109
3. MIG welding (Metal Inert Gas) . . . . . . . . . . . . . . . . . . . . . 110
4. Plasma MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
5. Laser welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6. Laser MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7. Resistance welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8. FSW - Friction Stir Welding . . . . . . . . . . . . . . . . . . . . . . . . 120
9. Surface preparation before welding . . . . . . . . . . . . . . . . 122
10. Quality control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
11. Design and prevention of deformation . . . . . . . . . . . . . . 126
IX. OTHER JOINING TECHNIQUES . . . . . . . . . . . . 129
1. Adhesive bonding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
2. Screwing and bold fastening . . . . . . . . . . . . . . . . . . . . . . 133
3. Riveting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
4. Snap-Lock & Clipping . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
X. DECORATION AND FINISHING . . . . . . . . . . . . 137
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
2. Possibilities with aluminium . . . . . . . . . . . . . . . . . . . . . . . 138
3. Mechanical finishing . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4. Chemical decoration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
XI. CORROSION RESISTANCE . . . . . . . . . . . . . . . . . . . 145
1. Definition of corrosion . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
2. Corrosion of aluminium . . . . . . . . . . . . . . . . . . . . . . . . . . 146
XII. CLEANING OF ALUMINIUM
COMMERCIAL VEHICLES . . . . . . . . . . . . . . . . . . . 153
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
2. The nature of stains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
3. The choise of detergent . . . . . . . . . . . . . . . . . . . . . . . . . . 155
4. Application of the detergent . . . . . . . . . . . . . . . . . . . . . . 155
XIII. REPAIR OF ALUMINIUM
COMMERCIAL VEHICLES . . . . . . . . . . . . . . . . . . . 157
1. Foreword . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
2. Execution of repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
3. Repair of aluminium chassis . . . . . . . . . . . . . . . . . . . . . . . . 159
4. MIG and TIG weld repairs . . . . . . . . . . . . . . . . . . . . . . . . . 160
Acknowledgments and photo credits . . . . . . . . . . . . . . . .162
5
EUROPEAN ALUMINIUM ASSOCIATION
6
1. ONE CENTURY OF ALUMINIUM IN TRANSPORT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2. EVOLUTION OF COMMERCIAL VEHICLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
3. ALUMINIUM APPLICATIONS AND WEIGHT SAVINGS . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
4. TODAY’S CONCERNS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
CHAPTER I I
ALUMI NI UM I N TRANSPORT
7
EUROPEAN ALUMINIUM ASSOCIATION
In 1903, the W right brothers
m ade aviation history w hen they
achieved the w orld’s first flight
pow ered by a lightw eight
engine m ade w ith alum inium
com ponents. Today, alum inium
is fundam ental to the aviation
industry. It accounts for m ore
than 60% of the structural
w eight of the A irbus A 380, and
up to 80% of short- and m id-
range aircrafts.
It w as in the 1920s that alu-
m inium shipping applications
started to expand due to new
alloys becom ing available for
m arine applications.
1. One century of al umi ni um i n transport
Ai rbus A380
8
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I A LUM I N I UM I N TRA N SPORT 8 | 9
Today, 1000 high-speed passen-
ger ships are in service, m ost of
them have a structure and
superstructure m ade of alu-
m inium . C ruise ship superstruc-
tures are com m only m ade of
alum inium , w hile over half of all
yachts are com pletely m ade out
of alum inium .
These ships take full advantage
of alum inium ’s lightness and
strength, as w ell as its corrosion-
resistance, an indispensable prop-
erty for m arine environm ents.
Crui se shi p wi t h al umi ni um superst ruct ure
Cat amaran UAI 50 (Babcock)
9
EUROPEAN ALUMINIUM ASSOCIATION
In the 1980s, alum inium
em erged as the m etal of choice
to low er running costs and to
im prove acceleration of m etros,
tram w ays, intercity and high
speed trains. In 1996, the TG V
D uplex train w as introduced,
transporting 40% m ore passen-
gers w hile w eighing 12% less
than the single deck version, all
thanks to its alum inium struc-
ture. Today, alum inium m etros
and tram s operate in m any cities
and alum inium trains are used
all over the w orld.
TGV Dupl ex (Al st om-SNCF)
10
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I A LUM I N I UM I N TRA N SPORT 10 | 11
The average volum e of alu-
m inium used in passenger cars
w as already 131kg in 2005.
The sam e year, one car in every
four produced in Europe had an
alum inium bonnet and around
one third of European cars w ere
already equipped w ith alu-
m inium bum per system s.
Al umi ni um bonnet
Al umi ni um bumper syst em prepared f or crash t est
In 1899, a sm all sports car w ith
an alum inium body w as unveiled
at the Berlin international car
exhibition. In 1948, Land Rover
started using alum inium outer
skin sheets.
Today, besides w ell-know n alu-
m inium -intensive cars like the
A udi A 8, m any cars contain sig-
nificant am ounts of alum inium .
11
EUROPEAN ALUMINIUM ASSOCIATION
1910
1930
1950
1976
TODAY
H aving m ade its debut in Parisian
buses in 1910, alum inium w as
used for a variety of elem ents in
com m ercial vehicles in the 1930s.
The 1950s saw the first alu-
m inium tankers, vans and tipping
vehicles. Today, m ost tankers and
silo sem i-trailers are m ade entirely
of alum inium . It is also frequently
used for vans, tipping or self-dis-
charging bodies and a m ultitude
of com ponents. C onsidering
today’s European fleet, alum inium
saves on average 800kg per artic-
ulated vehicle.
First aluminium parts
in Parisian buses
2. Evol uti on of commerci al vehi cl es
12
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I A LUM I N I UM I N TRA N SPORT 12 | 13
The key concern of transport
com panies is profitability.
The rising diesel price and the
investm ent in new engine tech-
nologies increase costs, w hile it
is hard to increase transport
prices due to the high com peti-
tion betw een operators.
A ny investm ent m ust therefore
have a very short payback tim e.
C onsequently, vehicle m anufac-
turers m ust constantly im prove
their perform ance at m inim um
costs. The choice of a m aterial
w ill therefore depend on its
price, its m echanical properties
and its im pact on vehicle pro-
duction costs.
From a society point of view ,
energy efficiency, reduction of
greenhouse gases and road
safety are in the priority list of
European authorities.
C hapter III explains how alu-
m inium helps to take up these
challenges.
4. Today’s
concerns
3. Aluminium applications
and weight savings
Some examples…
G Components for tractors
& rigid trucks
- cabin & door: -200kg
- chassis: -350kg
- powertrain parts: -125kg
- suspension parts: -110kg
G Complete superstructures
- rigid body: 90m2 = -800kg
- tipping body: -800 to -2200kg
- ADR fuel tank: 43000l = -1100kg
- self-discharging body
- silo
G Components
for superstructure
- curtain rails: 2x13.5m = -100kg
- front wall: -85kg
- rear door: -85kg
- side boards: 600mm = -240kg
- stanchions: 10x600mm = -50kg
- reefer floor
G Safety parts
- front bumpers : -15kg
- rear bumpers : -15kg
- side bumpers : -20kg
- front and rear under-run
protections
G Trailers sub-structures
- chassis: 13.5m = -700kg
- chassis: 6m = -300kg
- chassis+floor: 13,5m = -1100kg
- legs: -35kg
G Accessories
- air pressure vessels:
6x60l = -54kg
- diesel tank: 600l = -35kg
- toolbox: -15kg
- tail lift: -150kg
- wheels: 14 rims = -300kg
13
EUROPEAN ALUMINIUM ASSOCIATION
14
1. SHORT PAY-BACK . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1. 1. Increased payload + Higher residual value = Additional incomes . . . . . . . . . . . . . 16
1. 2. Fuel saving + long life + reduced maintenance = Cost savings . . . . . . . . . . . . . . . 16
1. 3. Make your own calculation on www.alutransport.org . . . . . . . . . . . . . . . . . . . . . 16
1. 4. Coping with road tolls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
1. 5. Reduced risk of work accident . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
2. ALUMINIUM PERFORMANCE PROPERTIES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
2. 1. High strength-to-weight and high stiffness-to-weight ratios . . . . . . . . . . . . . . . . 18
2. 2. Durability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2. 3. Stability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
2. 4. Diversity & functionality of semi-finished products, castings and forgings . . . . . 20
2. 5. Easy to work with . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
3. ENVIRONMENTAL AND SOCIAL BENEFITS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3. 1. Aluminium reduces CO
2
emissions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
3. 2. Aluminium as a complement to EURO IV & EURO V engines . . . . . . . . . . . . . . . . 22
3. 3. Aluminium improves road safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
3. 4. Aluminium is easily and economically recycled . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
4. ON THE ROAD… . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4. 1. Looking good forever . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
4. 2. Aluminium is easy to repair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
CHAPTER I I I
WHY USI NG ALUMI NI UM
15
EUROPEAN ALUMINIUM ASSOCIATION
Aluminium reduces dead vehicle
weight. When transporting high-
density freight, which usually sat-
urates the maximum gross vehi-
cle weight, aluminium allows the
loading of more goods. This
translates into additional income
and/or better competitiveness.
Furthermore, used aluminium
vehicles have a lot of success on
the second, and even third hand
market, where they are usually
sold for a very good price. Finally,
when they have reached the end
of their long service life they still
have a high scrap value. This is
due to the fact that aluminium is
easily recycled, without losing
any of its quality and saving 95%
of the primary energy input.
Make your own payback calcula-
tion on www.alutransport.org
and have a look at the example
beside.
1. Short pay-back
1.1. Increased payload + Higher residual value = Additional incomes
A study conducted by the IFEU
1
in cooperation with the TU-Graz
2
concluded that 1 ton saved on
the total weight of an articulated
truck leads to a fuel saving of 0.6
litres /100 km.
This saving occurs during trips
made below the maximum gross
vehicle weight, i.e. when trans-
porting low-density goods, for
partly loaded or empty trips.
Aluminium’s well-known corro-
sion resistance is an obvious
advantage in road transport: It
contributes to a long service life,
especially in vehicles which work
in conditions that can cause seri-
ous corrosion problems. No
painting or other surface protec-
tion is required and it is easy to
clean. Maintenance is therefore
kept to a minimum.
1.2. Fuel saving + long life + reduced maintenance = Cost savings
1.3. Make your own calculation on www.alutransport.org
1. Institut für Energie und Umwelt Forschung, Heidelberg, Germany
2. Technical University of Graz, Austria
16
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 16 | 17
1.4. Copi ng wi t h road t ol l s
A ccording to the “user pays”
principle, an increasing num ber
of countries are introducing road
tolls that increase cost per kilo-
m etre. O n the other hand,
increasing payload w ith alu-
m inium allow s spreading this
extra cost over a bigger tonnage
of goods.
In countries w here road toll is
lim ited to the heaviest vehicle
category, “m ini-sem i-trailers”are
built using a substantial am ount
of alum inium allow ing the oper-
ator to keep a good payload
w hile not exceeding the w eight
lim it w here a toll is applicable.
1.5. Reduced ri sk of work
acci dent
M obile parts that are m anipu-
lated at each delivery, like drop-
side w alls or rear doors, are
lighter to m ove w hen m ade out
of alum inium . This saves a lot of
effort for the drivers.
U sing extrusions w ith rounded
edges or folded sheets w ith round
corners for the floors of box vans
reduces the risk of injuries.
Mi ni -t rai l er (Tang Fahrzeugbau GmbH)
Road t ol l st at i on
17
EUROPEAN ALUMINIUM ASSOCIATION
A lum inium alloys used in com -
m ercial vehicles have strength-
to-w eight and stiffness-to-
w eight ratios com parable w ith
the m ost advanced m etals like
high strength steel and titanium .
These properties, am ong m any
others, are taken into account
w hen designing a vehicle.
N o w eight saving can be obtained
w ith alum inium if the design is
sim ply copied from steel.
D esigns optim ised for alum inium
are based on specific sections (20
to 40% higher beam s), sm ooth
transitions and clever joints,
w hich norm ally give 40-60%
w eight saving over com peting
m etals, as explained below .
To illustrate the upper and the
low er lim its of alum inium light-
w eighting, let’s analyze tw o
extrem e equivalence philoso-
phies “equal strength” and
“equal stiffness”to traditional
chassis beam .
2. Aluminium performance properties
2.1. Hi gh st rengt h-t o-wei ght and hi gh st i f f ness-t o-wei ght rat i os
Comparison of weight-optimised designs made with 3 different metals and 2 design criteria
EQUAL STRENGTH
St andard Hi gh st rengt h Al umi ni um
st eel st eel al l oy
Strength 1 = 1 = 1
Stiffness 1 > 0.30 < 0.56
Weight 1 > 0.71 > 0.42
Section height 1 > 0.65 < 1.18
EQUAL STIFFNESS
St andard Hi gh st rengt h Al umi ni um
st eel st eel al l oy
Strength 1 < 2.17 > 1.54
Stiffness 1 = 1 = 1
Weight 1 = 1 > 0.55
Section height 1 = 1 < 1.40
DEFINITION
St andard Hi gh st rengt h Al umi ni um
st eel st eel al l oy
Yield strength (M Pa) 350 760 250
E-M odulus (M Pa) 210000 210000 70000
D ensity (kg/m
3
) 7800 7800 2700
U nfair com parison!
18
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 18 | 19
A t equal strength:
•The alum inium beam is the
lightest, but has a low er stiffness
than the standard steel beam .
•The high-strength steel beam
ranks second for lightness, but its
stiffness is also the low est!
•The alum inium solution is
about 60% lighter than the stan-
dard steel one (0.42 vs. 1) and still
40% lighter than the high
strength steel one (0.42 vs. 0.71).
A t equal stiffness:
•The alum inium beam is the
lightest, w ith 45% w eight saved
(0.55 vs 1).
•The high strength steel beam
w eighs the sam e as the standard
steel beam , because, based on
the sam e parent m etal, both
m aterials have identical elastic
properties (E-m odulus).
•C om pared to the standard steel
beam , the alum inium one is
about 50% stronger, and the high
strength steel one about 120% .
C om paring an alum inium beam
designed for equal stiffness to a
standard steel beam and a high
strength m etal beam designed for
equal strength to that standard
steel beam , only show s sm all
w eight saving for alum inium
(0.55 vs. 0.71) but that compari-
son is unfair, as the latter w ill
have a m uch higher strength
(1.54 vs. 1) and a m uch higher
stiffness (1 vs. 0.30).
Last but not least, w e should
underline that further w eight
optim isation is possible w ith alu-
m inium because:
•The above com parison is
based on a standard beam
design, the so-called “double T”
•Finite elem ent m odelling
allow s a m ore precise definition
of m ost favorable section’s
geom etry;
•These sections, even if very
com plex, can easily be produced
w ith the alum inium extrusion
process.
•For parts w here strength is the
leading criteria, high-strength
alum inium alloys can also be
used and provide further w eight
savings
2.2. Durabi l i t y
Som e operators still fear prob-
lem s w ith alum inium trailer chas-
sis in heavy duty applications,
but they should know that the
lifespan is not m aterial related if
properly designed.
Experienced m anufacturers opti-
m ize their design for the m aterial
they use and are able to produce
alum inium chassis offering an
equivalent or longer lifespan but
at a m uch low er w eight than
conventional m odels.
It is also im portant to underline
that alum inium vehicles often
operate in transport segm ents
w here the load factors are the
highest (solid and liquid bulk,
public w orks etc…). In other
w ords, they are m uch m ore
intensively used than conven-
Unpai nt ed al umi ni um pat rol boat
(Al l Ameri can Mari ne)
19
EUROPEAN ALUMINIUM ASSOCIATION
tional ones, and this fact is taken
into account in the design of alu-
m inium vehicles.
C orrectly used, alum inium alloys
have been developed to offer
optim um corrosion resistance in
all environm ents. Just one exam -
ple: the w idespread use of
unpainted alum inium in m arine
applications.
2.3. St abi l i t y
A chieving IRTE
3
C lass A
4
tipping
stability standard for an alu-
m inium tipper chassis is no prob-
lem . A lum inium , according to
tests carried out in the sum m er
of 2002 has no issues w ith flex-
ing and easily provides the equiv-
alent rigidity of steel.
Indeed, a full-alum inium vehicle,
significantly lighter than others,
passed the IRTE C lass A test at 44
tonnes w ith its standard chassis,
rem inding everyone that an
appropriate design leads to both
lightness and torsional stiffness.
3. Institute of Road Transport Engineers,
U K.
4. “C lass A ”standard states that a
trailer should be able to tilt sidew ays 7°
w ithout falling w ith a fully loaded and
raised body.
Ti ppi ng st abi l i t y t est (STAS)
2.4. Di versi t y & f unct i onal i t y of semi -f i ni shed product s,
cast i ngs and f orgi ngs
Vehicle designers and m anufac-
turers have a w ide range of alu-
m inium alloy sem i-finished prod-
ucts from w hich to choose:
•Rolled sem is: sheets, tread
plates (floor plates), pre-painted
sheets
•Extruded sem is: hollow or solid
shapes, standard or custom ized
•C astings and forgings
20
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 20 | 21
This diversity of sem i-finished
products m akes it possible to:
•D esign structural elem ents
w ith special functions such as
shapes w ith grooves for screw
heads, hydraulic circuits, inertia
shapes, snap-locks, w elding
flanges etc.
•Save on tim e and cost for
assem bly and finishing. This can
com pensate for the added raw
m aterial cost of structures m ade
from alum inium alloys com pared
w ith equivalent steel structures.
•Reduce stress due to w elding
by placing castings at assem bly
intersections or using special
extrusions to divert w elding
stresses into less stressed areas of
a fabricated structure.
•D esign com plex cast or forged
shapes.
2.5. Easy t o work wi t h
A lum inium alloys used in the
m anufacture of com m ercial vehi-
cles and their accessories are
easy to process. They lend them -
selves to a variety of shaping and
joining techniques that w ill be
review ed in chapters 7, 8 & 9.
In a nutshell, alum inium can
easily be
•cut: saw ing, shearing, w ater jet,
laser or plasm a cutting
•m achined: m illing, drilling
•bent
•joined: w elding, adhesive bond-
ing,bolting and riveting
Furtherm ore, being light, alu-
m inium is easy to handle in the
w orkshop.
Vari ous al umi ni um product s
21
EUROPEAN ALUMINIUM ASSOCIATION
To achieve em ission reductions, it
is not only im portant to develop
low -em ission engines, but also to
use them in the m ost rational
w ay possible. Saving w eight w ith
alum inium is a good w ay of
achieving this objective as
explained below .
A lum inium contributes to the
reduction of C O
2
em issions from
road transport as follow s:
•W hen carrying heavy goods, it
increases the load capacity of
vehicles and therefore im proves
transport perform ance, allow ing
m ore goods to be carried per
trip. In this case, one ton saved
on the dead w eight of an articu-
lated truck saves 1,500 liters of
diesel fuel over 100,000 km .
•W hen carrying volum inous
goods, it reduces the overall
w eight, low ering fuel consum p-
tion per kilom eter. In this case,
one ton saved on the dead
w eight of an articulated truck
saves 600 liters of diesel fuel over
100,000 km .
•W hen carrying passengers, it
reduces the overall w eight and
low ers fuel consum ption. O ne
ton saved on an urban bus saves
betw een 1,700-1,900 liters of
diesel fuel per 100,000 km .
Taking prim ary production, use
stage and end-of-life recycling
into account, life-cycle savings
have been estim ated as follow s:
•1kg of alum inium in today’s
average articulated truck saves
28kg of C O
2
•1kg of alum inium in an urban
bus typically saves 40-45kg of C O
2
3.2. Al umi ni um as
a compl ement t o EURO IV
& EURO V engi nes
The European Environm ent
D irectives for trucks date back to
1988, w hile the first standard
lim iting em issions of nitrogen
oxides (N O x) and particulates
(PM ) from heavy-duty diesel
engines w ere introduced at the
beginning of the 1990’s.
The EU RO IV and EU RO V stan-
dards represent a dram atic reduc-
tion of N O
x
and PM em issions.
H ow ever, they also im pose new
com bustion processes and
exhaust after-treatm ent techni-
ques representing an additional
w eight-penalty up to 300kg.
U sing m ore alum inium com po-
nents allow s the m anufacturer to
com pensate for this w eight
penalty. The payload can there-
fore be preserved and even
increased.
3. Environmental and social Benefits
3.1. Al umi ni um reduces CO
2
emi ssi ons
22
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 22 | 23
In the context of its Road Safety
A ction Program m e, the European
C om m ission is looking into the
introduction of crash energy
absorption criteria for trucks. The
alum inium industry has already
developed several solutions for
the autom otive and railw ay sec-
tors and w ould be ready to take
up this challenge for trucks.
Regarding m etal deform ation
that energy-absorbing elem ents
undergo upon im pact, alu-
m inium system s m ake it possible
to absorb significantly m ore
crash energy per unit of w eight
than traditional system s. A s a
rule of thum b, the light-w eight-
ing potential exceeds 40% .
For this reason, alum inium is very
w ell suited for front, rear and
side bum pers.
A lum inium elem ents can also be
used to im prove the energy
absorbing potential of front and
rear end under-run protection
devices, and m ay also be used to
build soft deform able truck
noses.
Last but not least, extra safety
features alw ays m ean additional
w eight, w hich can be balanced
by replacing heavy m aterials by
alum inium .
3.3. Al umi ni um i mproves road saf et y
Truck wi t h crash-modul e
23
EUROPEAN ALUMINIUM ASSOCIATION
U nlike traditional vehicles that
are exported to end their life a
long w ay from Europe, alu-
m inium -intensive trailers gener-
ally spend their entire life in our
continent, w here they are even-
tually dism antled
5
. D ue to the
high value of alum inium scrap,
the m otivation to sell to a scrap
m erchant is very high and land-
filling is avoided.
Recycled alum inium does not
loose any of its quality and saves
95% of the prim ary production
energy input. The energy
required to produce prim ary alu-
m inium is not lost: it is “stored in
the m etal”.
3.4. Al umi ni um i s easi l y and economi cal l y recycl ed
5. “The fate of alum inium from end-of-
life com m ercial vehicles”, U niversité de
Technologie de Troyes
Al umi ni um t i pper on scrap yard (Gal l oo recycl i ng)
24
4. On the road…
4.1. Looki ng good f orever
The m odern com m ercial vehicle
cannot escape the pressures of
industrial design. O perators w ant
their vehicles to look good w ith
clean, pleasing lines, som ething
w hich alum inium alloy sem is are
ideal for producing.
For exam ple, using functional
extrusions and plain or pre-
painted alum inium sheet that is
easy to shape, it is a straightfor-
w ard m atter to produce vans
w ith rounded body corners both
inside and out.
W ith tippers and self-discharging
bodies, this m akes for a sm ooth
unloading and easier cleaning. In
addition, using double w all alu-
m inium extruded boards allow s
the preservation of a perfect
exterior surface over the tim e.
Im age conscious operators appre-
ciate this type of construction very
m uch.
A lum inium is used to produce
the lightest, the strongest and
the m ost beautiful w heels.
Last but not least, no corrosion
w ill appear after im pact on alu-
m inium parts, therefore preserv-
ing the im age of the com pany.
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 24 | 25
8 years ol d al umi ni um t i ppi ng body
re-used on a new t ruck
25
EUROPEAN ALUMINIUM ASSOCIATION
4.2. Al umi ni um i s easy
t o repai r
Few people know that Land
Rovers have had alum inium clo-
sure panels since 1948, and in
the last 50 years, nobody has
ever com plained about repair
problem s. This illustrates the fact
that repair is possible, but alu-
m inium repair techniques are
definitely different from those of
steel. Leading chassis m anufac-
turers have set up a European
dealer netw ork w here an effi-
cient repair service is offered.
Doubl e wal l ext ruded boards f or t i ppers
Forged al umi ni um wheel
26
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I I I WHY USI N G A LUM I N I UM 26 | 27
Repai r
of an al umi ni um t i pper
(Benal u)
27
EUROPEAN ALUMINIUM ASSOCIATION
28
1. ALUMINIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30
1. 1. What are the advantages of an aluminium vehicles? . . . . . . . . . . . . . . . . . . . . . . . 30
1. 2. Is there an additional cost for an aluminium vehicle? . . . . . . . . . . . . . . . . . . . . . . 30
1. 3. What are the main benefits for the environment? . . . . . . . . . . . . . . . . . . . . . . . . 30
1. 4. Is it necessary to paint an aluminium vehicle? . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1. 5. Is it possible to repair an aluminium vehicle? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
1. 6. Does aluminium burn ? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
2. ALUMINIUM CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32
2.1. How is an aluminium chassis designed and what are the weight savings achievable? . 32
2. 2. Are there different aluminium chassis designs? . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
2. 3. Is the life of an aluminium chassis shorter than a steel chassis? . . . . . . . . . . . . . 34
2. 4. How does aluminium compete with high strength steel? . . . . . . . . . . . . . . . . . . . 34
3. ALUMINIUM TIPPERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
3. 1. Are there different aluminium tipping body designs? . . . . . . . . . . . . . . . . . . . . . . 35
3. 2. What about the wear resistance of aluminium tipping bodies . . . . . . . . . . . . . . . 35
3. 3. What type of chassis is needed for an aluminium tipper body? . . . . . . . . . . . . . . 36
3. 4. What about tipping stability? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
4. ALUMINIUM TANKERS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
4. 1. How should a tank for the transport of dangerous goods (ADR) be designed? . 37
4. 2. Which alloys are suitable for ADR tanks? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
CHAPTER I V
FREQUENTLY
ASKED QUESTI ONS
29
EUROPEAN ALUMINIUM ASSOCIATION
1. Al umi ni um
1.1. What ar e t he advant ages of an al umi ni um vehi cl es?
1.2. I s t her e an addi t i onal cost f or an al umi ni um vehi cl e?
Yes, alum inium vehicles are slightly
m ore expensive than equivalent
steel designs. If w e analyse the dif-
ference in detail, w e can see that,
w hen heavy goods are trans-
ported, the additional investm ent
is paid back after less than tw o
years. M ake your ow n calculations
on w w w .alutransport.org.
1.3. What ar e t he mai n benef i t s f or t he envi r onment ?
A lum inium contributes to the
reduction of C O
2
em issions from
road transport as follow s:
•W hen carrying heavy goods,
it increases the load capacity of
vehicles and therefore im proves
transport perform ance, allow ing
m ore goods to be carried per
trip. In this case, one ton saved
on the dead w eight of an artic-
ulated truck saves 1,500 litres of
diesel fuel over 100,000 km .
•W hen carrying volum inous
goods, it reduces the overall
w eight, low ering fuel consum p-
tion per kilom etre. In this case,
one ton saved on the dead
w eight of an articulated truck
saves 600 litres of diesel fuel
over 100,000 km .
Taking prim ary production, use
stage and end-of-life recycling
into account, life-cycle savings
have been estim ated
1
that 1kg
of alum inium in today’s aver-
age articulated truck saves
28kg of C O
2
.
Truck fleet operators benefit
from a better perform ance of
their fleet.
There is a significant payload
increase w hich m akes the fleet
m uch m ore profitable. A nother
fact is cost savings that result
from sm aller fleets w ith less
staff, low er fuel bills and low er
road toll costs.
Trailer rental com panies can offer
operators sem i-trailers w ith a bet-
ter perform ance. D ue to the
higher payload, the longer life
and the higher residual value of
the equipm ent these com panies
can generate m ore profit by
using state-of-the-art equipm ent.
1. CO
2
reduction potential of aluminium
for articulated trucks, EA A (European
A lum inium A ssociation), 2005
Al umi ni um bodi ed t ruck
30
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I V FREQUEN TLY A SKED QUESTI ON S 30 | 31
N o, it is not. A lum inium w ith its
natural «alum ina» layer has an
excellent protection perform -
ance. If an operator chooses to
pay extra m oney (and w eight
too!) for the paint finish, the
m otivation to do so lies in hav-
ing a fleet w ith a particular
branding.
1.4. I s i t necessar y t o pai nt an al umi ni um vehi cl e?
1.5. I s i t possi bl e t o r epai r an al umi ni um vehi cl e?
It is often said that alum inium
vehicles cannot be repaired,
how ever this is totally w rong.
Few people know that Land
Rover cars have had an alu-
m inium body since the end of
w orld w ar tw o, and in the last
50 years nobody has ever com -
plained about repair problem s.
This illustrates the fact that
repair is possible as for any
other m aterials, but alum inium
repair techniques are definitely
different from those of steel.
Please refer to the C hapter XIV
for detailed inform ation.
Leading chassis m anufacturers
have set up a European dealer
netw ork w here an efficient
repair service is offered.
1.6. Does al umi ni um bur n?
N O , alum inium and its alloys
are, under atm ospheric condi-
tions, totally non-com bustible
and do not contribute to the
spread of fire.
A lum inium alloys w ill how ever
m elt at around 650°C , but w ith-
out releasing harm ful gases.
Repai r of an al umi ni um t i pper (St as)
31
EUROPEAN ALUMINIUM ASSOCIATION
Leading European trailer m anu-
facturers are using strength,
stiffness and durability criteria.
N o w eight saving can be
obtained w ith alum inium if
design is sim ply copied from
steel. D esigns optim ised for alu-
m inium are based on specific
sections (20 to 40% higher
beam s), sm ooth transitions and
clever joints, w hich norm ally
give 40-60% w eight saving over
com peting m etals (see C hapter
III), as explained below .
1) A good light-w eight trailer
has to be as strong as a tradi-
tional m odel. If this w ould be
the sole criteria, the w eight sav-
ing obtained w ith alum inium
w ould be m axim ized (up to
60% ) and high strength steel
solutions w ould provide about
half the w eight saving achiev-
able w ith alum inium (about
30% ).
2. Al umi ni um chassi s
2.1. How i s an al umi ni um chassi s desi gned and w hat ar e t he w ei ght savi ngs
achi evabl e?
Chassi s f or al umi ni um t i pper (Benal u)
32
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I V FREQUEN TLY A SKED QUESTI ON S 32 | 33
2) A m inim um stiffness is gener-
ally required.
•If this stiffness has to be equal
w ith standard steel m odels,
w eight savings obtained w ith
alum inium w ill be around 45%
w ith a superior strength, but
high strength steel cannot
achieve any w eight saving.
•If the m inim um stiffness
required is low er than the one of
standard steel m odels, w eight
savings obtained w ith alum inium
w ill be som ew here betw een
45% & 60% and w eight savings
obtained w ith high strength
steel som ew here betw een zero
and half of w hat can be
achieved w ith alum inium .
3) Vehicles durability m ust be
insured. A s alum inium vehicles
are m uch m ore intensively used
than conventional ones, their
resistance to fatigue m ust be
higher. This result is obtained
w ith a proper design. A m ong of
a lot of others, higher sections,
sm ooth transitions and clever
joints are keys to success.
2.2. Ar e t her e di f f er ent al umi ni um chassi s desi gns?
Each m anufacturer has its ow n
design, w hich to a high degree
depends on the w orking condi-
tions the vehicle is m ade for and
on the specific m anufacturing
experiences of the chassis pro-
ducer (e.g. som e prefer fully
w elded constructions w hereas
others prefer m ixed w elded and
bolted constructions). It is also
im portant to underline that alu-
m inium vehicles are m uch m ore
intensively used than conven-
tional ones, and this fact is
taken into account in the design
of vehicles. A part from that,
there are tw o dom inating
design philosophies in the chas-
sis w orld.
In countries like Italy, w here
equal stiffness w ith steel m odels
seem s to be a m ust, deflection is
the m ain criteria, and this gener-
ally leads to longer lifetim e than
conventional m odels, coupled
w ith an attractive w eight saving.
In other countries, equal lifetim e
w ith steel m odels w ill be the
m ain criteria. A good design w ill
lead to, at least, an equivalent
lifetim e, stiffness w ithin require-
m ents (even though it m ay be
slightly low er than steel m od-
els), but the w eight saving w ill
be m axim ized.
In any case, they w ill usually be
stronger than classic m odels,
and the risk for starting yield
failure from static overload w ill
be low er for alum inium chassis.
Chassi s f or al umi ni um t i pper (Leci ñena)
33
EUROPEAN ALUMINIUM ASSOCIATION
The lifespan of a chassis is a design
issue and not a m aterial issue.
A lum inium chassis are m ostly
used in transport segm ents
w here the load factors are the
highest (solid & liquid bulk
tanks, tippers), nevertheless w ell
designed vehicles can easily
exceed 20 years of service life.
2.3. I s t he l i f e of an al umi ni um chassi s shor t er t han a st eel chassi s?
2.4. How does al umi ni um compet e w i t h hi gh st r engt h st eel ?
W e should m ake a distinction
betw een pure alum inium and
alum inium alloys.
Pure alum inium is never used in
com m ercial vehicles. A w ide
variety of alum inium alloys do
exist, including high strength
solutions.
W hat is seldom com m unicated
is that all alloys based on the
sam e parent m etal have nearly
the sam e elastic properties.
This m eans that if som eone is
looking for a lightw eight alter-
native to a standard chassis
w hile keeping the sam e stiff-
ness, the only solution is to
change the m aterial e.g. sw itch-
ing from steel to alum inium (see
C hapter III).
Bol t ed al umi ni um chassi s f or t i pper
(Menci )
34
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I V FREQUEN TLY A SKED QUESTI ON S 34 | 35
Yes, there are a lot of tipper
variants and all of them can be
built using dedicated alum inium
sem i-products that offer high
productivity for m anufacturers,
as w ell as increased payload,
low running costs and a great
fleet im age to operators. For
m ore details, please have a look
at C hapter VI.
3. Al umi ni um ti ppers
3.1. Ar e t her e di f f er ent al umi ni um t i ppi ng body desi gns?
3.2. What about t he w ear r esi st ance of al umi ni um t i ppi ng bodi es
The w ear condition can vary
extrem ely from one load to
another. Therefore it is not
alw ays possible to link the actual
hardness of an alloy to the w ear
resistance. It w as found out that
for a very large extent, the type
of load is a decisive factor.
The choice of m aterial for the
construction of tipping trailers is
now adays often a question of
specific experiences, m aterial
availability and m anufacturer’s
specific production m ethods.
Typical bottom plate m aterial is:
•5083 H 32, H 321, H 34
•5086 H 24
•5383 H 34
•5454 H 22, H 24
•5456 H 34
or other, m ill-specific alloy types.
Typical values for bottom plate
thickness are listed below :
•6 m m for light-duty opera-
tions like agricultural products,
coal or sand transport
•8 m m for m edium -duty serv-
ice like recycling products
•10 m m for heavy-duty trans-
port like gravel
•U p to 12 m m in extrem e cases
Please refer to C hapter VI for
m ore details.
35
EUROPEAN ALUMINIUM ASSOCIATION
Som e operators still fear prob-
lem s w ith alum inium trailer
chassis in heavy-duty applica-
tions, but they should know
that strength is not m aterial
related. Indeed, strength, like
stiffness and lifetim e, are only
design criteria. Experienced
m anufacturers are able to pro-
duce alum inium chassis offering
the sam e perform ance but at a
m uch low er w eight than con-
ventional steel m odels.
3.3. What t ype of chassi s i s needed f or an al umi ni um t i pper body?
3.4. What about t i ppi ng st abi l i t y?
It is often said that achieving
the IRTE
2
C lass A
3
tipping sta-
bility standard for an alu-
m inium tipper chassis w ould
be difficult sim ply because "it
flexes too m uch" or that, to
provide the equivalent rigidity
of a steel chassis "the lightness
benefit w ould be practically
elim inated", but tests run dur-
ing sum m er 2002 confirm ed
that both statem ents w ere
totally w rong.
Indeed, a full-alum inium vehicle,
significantly lighter than others,
passed the IRTE C lass A test at
44 tonnes w ith its standard
chassis rem inding everybody
that an appropriate design leads
to both lightness and torsional
stiffness.
2. British Institute of Road Transport
Engineers (IRTE)
3. IRTE's "C lass A " stability standard
for tipping on uneven ground states
that a trailer should be able to tilt side-
w ays 7° w ithout falling w ith a fully
loaded and raised body.
IRTE t i ppi ng st abi l i t y t est (STAS)
36
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER I V FREQUEN TLY A SKED QUESTI ON S 36 | 37
Tanks for the transport of dan-
gerous goods have to be built
according to the rules defined in
the follow ing agreem ent and
standards:
•A D R: A greem ent for the
transport of D angerous goods
by Road
4
•EN 13094 “Tanks for the
transport of dangerous goods -
M etallic tanks w ith a w orking
pressure not exceeding 0.5 bar -
D esign and construction”
•EN 14025 “Tanks for the
transport of dangerous goods -
M etallic pressure tanks - D esign
and construction”
M ore details are given in
C hapter VI.
4. Al umi ni um tankers
4. See ADR, Annex A, Part 6, Chapter 6.8:
http://w w w .unece.org/trans/danger/danger.htm
4.1. How shoul d a t ank f or t he t r anspor t of danger ous
goods (ADR) be desi gned?
4.2. Whi ch al l oys ar e
sui t abl e f or ADR t anks?
Suitable alum inium alloys for
that application are listed in
standard EN 14286 “A lum inium
and alum inium alloys - w eldable
rolled products for tanks for the
storage and transportation of
dangerous goods”as w ell as in
chapter V.
A lum inium suppliers are listed in
the “links”section of the w eb-
site w w w .alutransport.org .
Al umi ni um road t anker (Schrader)
37
EUROPEAN ALUMINIUM ASSOCIATION
38
1. FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
2. INTERNATIONAL PRODUCT DESIGNATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
3. BASIC TEMPER DESIGNATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
4. SUBDIVISIONS OF H TEMPER DESIGNATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42
5. SUBDIVISION OF T TEMPER DESIGNATIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43
6. TYPICAL ALLOYS FOR COMMERCIAL VEHICLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
6. 1. Flat rolled products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
6. 2. Extruded products (forged products) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
6. 3. Castings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48
6. 4. Selection guide for the different alloys (indicative) . . . . . . . . . . . . . . . . . . . . . . . 49
7. INFLUENCE OF TEMPERATURE ON MECHANICAL PROPERTIES . . . . . . . . . . . . . . . . . . . . 50
7. 1. Elevated temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
7. 2. Low and very low temperatures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
8. INFLUENCE OF FABRICATION ON THE PROPERTIES OF THE ALLOYS . . . . . . . . . . . . . . . 52
8. 1. Work hardening of non-heat treatable alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8. 2. Softening by annealing and recovery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
8. 3. Heat treatable alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
8. 4. Castings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
9. LIST OF STANDARDS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55
CHAPTER V
ALUMINIUM ALLOYS
FOR COMMERCIAL VEHICLES
39
EUROPEAN ALUMINIUM ASSOCIATION
A lum inium in its pure form is a
very soft m etal and hence not
suited for structural applica-
tions. Thanks to the addition of
alloying elem ents such as cop-
per, m anganese, m agnesium ,
zinc etc… and thanks to ade-
quate production processes, the
physical and m echanical proper-
ties can be varied in a great
range m aking it possible to have
suitable alloys for literally all
applications.
A s the A lum inium Industry is a
global industry there is the enor-
m ous chance, that the product
designation is uniform alm ost all
over the w orld. C om pany spe-
cific trade nam es are often com -
plem ented by the standardized
designation.
A ll relevant standards are listed
at the end of this chapter.
1. Foreword
Al umi ni um rol l i ng mi l l
40
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 40 | 41
2. Internati onal product desi gnati on
From these eight categories are
three fam ilies so called “non heat
treatable“, or “w ork hardening”
alloys (1xxx, 3xxx, 5xxx) and four
“heat treatable alloys”(2xxx,
4xxx, 6xxx, 7xxx). The 8xxx fam ily
cannot be attributed to one or
the other group.
The alloy num ber can be pre-
ceded by a letter X w hich indi-
cates that it is an experim ental
alloy, or follow ed by a letter A
w hich says that this is a national
variation of the basic alloy.
The physical and m echanical
properties of these alloys not only
depend on their chem ical com po-
sition but also to a great extent on
the m anufacturing process in the
alum inium plant and on the trans-
form ation process of the sem i-
finished to the finished product.
These processes are characterized
w ith the so called “tem per desig-
nation”w hich attends the alloy
num ber. W hen alloy num ber and
tem per designation are indicated,
the m etal is clearly identified and
its properties defined.
In order to identify the various
alloys, 4-digit num bers have
been standardized for w rought
alloys (see EN 573-1) and 5-digit
num bers for cast alloys.
A list of all registered w rought
alloys and their chem ical com posi-
tion can be found in EN 573-3 for
Europe and in the so-called “Teal
sheets
1
”at international level.
A list of all registered cast alloys
can be found in EN 1706.
A selection of alloys for use in
com m ercial vehicles w ill be pre-
sented in section 6.
The first digit of the alloy num ber
indicates the dom inant alloying
elem ent; the rem aining digits are
just num bers for identification
purposes (Table V.1). Just in the
case of pure alum inium the last
tw o digits of the 4-digit num ber
indicate the percentage of purity
above 99.0% . E.g. 1070 m eans
alum inium w ith at least 99.70%
of alum inium or, in other w ords
less than 0.30% im purities.
1. The latest edition of the Teal Sheets is available for free dow nload from the EA A w ebsite
http://w w w .eaa.net/en/about-alum inium /standards/international-registration/
CATEGORIES OF ALUMINIUM ALLOYS
Dominant alloying element wrought alloy cast alloy
N one (“pure alum inium ”) 1xxx
C opper 2xxx 2xxx
M anganese 3xxx
Silicon 4xxx 4xxxx
M agnesium 5xxx 5xxxx
M agnesium and Silicon 6xxx
Zinc and M agnesium (w ith or w ithout copper) 7xxx 7xxxx
O ther elem ents (e.g. Iron or Lithium ) 8xxx
TABLE V.1
41
EUROPEAN ALUMINIUM ASSOCIATION
• F - as fabricated: this condi-
tion designates products m ade by
plastic deform ation w ithout any
particular control of the rates of
hardening or softening by defor-
m ation or any heat treatm ent.
• O - fully annealed: this con-
dition is the m ost ductile and is
obtained by the process of anneal-
ing w ithout any subsequent
w ork-hardening or by hot rolling
at tem peratures above the
recrystallisation tem perature.
• H - strain-hardened and pos-
sibly partially softened: this
relates to strain-hardened prod-
ucts w ith or w ithout subsequent
holding at a tem perature high
enough to induce partial soften-
ing of the m etal.
• T - heat treated: heat treat-
m ent can com bine som e or all of
the follow ing operations: solu-
tion treatm ent, quenching, age
hardening, artificial ageing and
possible plastic deform ation.
For m ore details, please refer to
EN 515.
3. Basi c temper desi gnati ons
4. Subdi vi si ons of H temper desi gnati ons
The first digit after H indicates
the specific com bination of basic
operations:
• H1X: w ork-hardened only.
These designations identify prod-
ucts that are w ork-hardened
to obtain the desired strength
w ithout supplem entary heat
treatm ent.
• H2X: w ork-hardened and par-
tially annealed. These designa-
tions apply to products w hich are
w ork-hardened m ore than the
desired final am ount and then
reduced in strength to the
desired level by partial annealing.
• H3X: w ork-hardened and sta-
bilized. These designations apply
to products w hich are w ork-
hardened and w hose m echanical
properties are stabilized either by
a low tem perature heat treat-
m ent or as a result of heat intro-
duced during fabrication.
For m ore details, please refer to
EN 515.
The second digit follow ing the
letter H indicates the final degree
of strain hardening, as identified
by the m inim um value of the ulti-
m ate tensile strength.
• 8 has been assigned to the hard-
est tem per norm ally produced.
• Tem pers betw een O (annealed)
and H X8 are designated by
num erals 1 to 7.
• HX4 designates tem pers
w hose ultim ate tensile strength is
approxim ately m idw ay betw een
that of the O tem per and that of
the H X8 tem pers.
• HX2 designates tem pers
w hose ultim ate tensile strength
is approxim ately m idw ay betw een
that of the O tem per and that of
the H X4 tem pers.
• HX6 designates tem pers
w hose ultim ate tensile strength is
approxim ately m idw ay betw een
that of the H X4 tem pers and that
of the H X8 tem pers
• H X1, H X3, H X5, H X7 designate
tem pers interm ediate betw een
those defined above. N ote: These
tem per designations are not
included in EN 515. M echanical
properties of these tem pers shall
42
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 42 | 43
be agreed betw een the m anufac-
turer and the custom er.
The third digit, w hen used, indi-
cates a variation of a tw o-digit
tem per.
• HX11 applies to products that
incur sufficient strain-hardening after
the final annealing such that they fail
to qualify as annealed but not so
consistent an am ount of strain-hard-
ening that they qualify as HX1.
• H112 applies to products that
m ay acquire som e strain-hardening
from w orking at an elevated
tem perature or from a lim ited
am ount of cold w ork, and for
w hich there are no upper
m echanical property lim its.
• H116 applies to products,
m ade of those alloys of the 5XXX
group in w hich the m agnesium
content is 3% nom inal or m ore.
Products are strain hardened at
the last operation to specified
tensile property lim its and m eet
specified levels of corrosion
resistance in accelerated type
corrosion tests. C orrosion tests
include inter-granular and exfoli-
ation. This tem per is suitable for
continuous service at tem pera-
tures not higher than 65°C .
The first digit follow ing the let-
ter T is used to identify the spe-
cific sequences of basic treat-
m ents. N um erals 1 to 10 have
been assigned as follow s:
• T1: C ooled from an elevated
tem perature shaping process and
naturally aged to a substantially
stable condition
• T2: C ooled from an elevated
tem perature shaping process,
cold-w orked, and naturally aged
to a substantially stable condition
• T3: Solution heat-treated cold-
w orked, and naturally aged to a
substantially stable condition
• T4: Solution heat-treated and
naturally aged to a substantially
stable condition
• T5: C ooled from an elevated
tem perature shaping process and
then artificially aged
• T6: Solution heat-treated and
then artificially aged
• T7: Solution heat-treated and
over-aged/stabilized
• T8: Solution heat-treated, cold
w orked and then artificially aged
• T9: Solution heat-treated, artifi-
cially aged and then cold-w orked
• T10: C ooled from an elevated
tem perature shaping process,
cold-w orked, and then artificially
aged.
For m ore details, please refer to
EN 515.
5. Subdi vi si on of T temper desi gnati ons
Ext rusi on press
43
EUROPEAN ALUMINIUM ASSOCIATION
6. Typi cal al l oys f or commerci al vehi cl es
O ut of the vast variety of know n
alloys as listed in EN 573-3 and
in the Teal Sheets, just a few are
of im portance for the m anufac-
ture of com m ercial vehicles.
Selection criteria are:
• availability of sem i-finished
products
• m echanical properties
• physical properties
• suitability for fabrication
• w eldability
• corrosion resistance
In the follow ing tables the m ost
w idely used alloys for the appli-
cation in com m ercial vehicles
are presented.
Al umi ni um coi l s
44
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 44 | 45
REFERENCE STANDARDS FOR MECHANICAL PROPERTIES OF
WROUGHT ALLOYS – FLAT ROLLED PRODUCTS
Alloy Standards
2
3003 EN 485-2
5005 EN 485-2
5059 EN 485-2 and EN 14286
5083 EN 485-2 and EN 14286
5086 EN 485-2 and EN 14286
5088 EN 485-2 and EN 14286
5182 EN 485-2 and EN 14286
5186 EN 14286
5383 EN 485-2 and EN 14286
5454 EN 485-2 and EN 14286
5754 EN 485-2 and EN 14286
6061 EN 485-2
6082 EN 485-2
TABLE V.2
6.1. Fl at r ol l ed pr oduct s
In com m ercial vehicles, the m ost
com m only used alloys are 3003,
5005, 5059, 5083, 5086, 5088,
5182, 5186, 5383, 5454, 5456,
5754, 6061 and 6082.
The m echanical properties of
these alloys can be found in the
standards listed in Table V.2 and
Table V.3 gives indications on
engineering suitability.
2. See standards denom inations at the end of this chapter section 9.
Al umi ni um rol l i ng sl abs
45
EUROPEAN ALUMINIUM ASSOCIATION
ENGINEERING SUITABILITY FOR ROAD TRANSPORT APPLICATIONS –
FLAT ROLLED PRODUCTS
Alloy Temper Shaping Welding Anodizing Corrosion resistance
3003 H 14,H 24,H 16 B A A A
5005 H 14,H 24 B A A A
5059 O , H 111 B A A A
5083 O ,H 111 A A A A
H 116,H 22,H 24, H 34 C A A A
5086 O ,H 111 A A A A
H 116,H 22,H 24 C A A A
5088 O , H 111 A A A A
5182 O , H 111 A A A A
5186 O , H 111 A A A A
5383 H 22, H 32 B A A A
5454 O ,H 111 A A A A
H 22,H 24 B A A A
5456 H 34 C A A A
5754 O ,H 111 A A A A
H 22,H 24 B A A A
6061 T4 C A A A
T6 D A A A
6082 T4 C A A A
T6 D A A A
A = very good; B = good; C = fair; D = poor, to be avoided
TABLE V.3
46
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 46 | 47
6.2. Ext r uded pr oduct s
(f or ged pr oduct s)
In com m ercial vehicles, the m ost
com m only used alloys are 6060,
6005A , 6008, 6106, 6082,
6061 and 7020.
The m echanical properties of
these alloys can be found in
standard EN 755-2 and Table V.4
gives indications on their engi-
neering suitability.
ENGINEERING SUITABILITY – EXTRUDED & FORGED PRODUCTS
Alloy Temper Welding Anodizing Corrosion resistance
6060 all A A A
6005A all A A A
6008 all A A A
6106 all A A A
6082 all A A A
6061 all A A A
7020 T6 A A C
7003 T6/T7 A A B
7108 T6/T7 A A B
A = very good; B = good; C = fair; D = poor, to be avoided
TABLE V.4
Al umi ni um ext rusi on bi l l et s
47
EUROPEAN ALUMINIUM ASSOCIATION
6.3. Cast i ngs
In com m ercial vehicles, the
m ost com m only used alloys are
21100, 42000, 42100, 43000,
44000.
Their chem ical com position and
m echanical properties can be
found in standard EN 1706 and
Table V.5 reflects their casting
characteristics.
CASTING CHARACTERISTICS
Alloy Fluidity Resistance to Pressure Machinability Corrosion
hot tearing tightness resistance
21100 C D D A D
42000 B A B B B/C
42100 B A B B B
43000 A A B B B
44000 A A A C B
A = very good; B = good; C = fair; D = poor, to be avoided
TABLE V.5
Semi -t rai l er chassi s beam
made out of t wo ext ruded f l anges
and a sheet as web
Ext ruded rai l f or sl i di ng curt ai n
48
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 48 | 49
6.4. Sel ect i on gui de f or t he di f f er ent al l oys (i ndi cat i ve)
Beside these w ell know n alloys
it is possible to define, in coop-
eration w ith the supplier of the
sem is, tailor m ade products that
offer best perform ance for the
foreseen purpose.
Al l oy, t emper
3003* , 5005* , 5052*
6005 T6, 6005A T6, 6063A T6
6060 T6, 6063 T6
* coat ed sheet s
Van body
Ti pper wi t h ri bbed si des
Curt ai nsi der body
Ti pper or sel f -di schargi ng
body wi t h smoot h si des
Al l oy, t emper
6005 T6, 6005A T6, 6005A T5
6005 T6
6060 T5/T6
6063 T6
6005AT6
5083 H111, 5754 H111
5083 H34/H32/H321 • 5086 H24
5383 H34 • 5454 H22/H24
5456 H34
i n case of sel f -di schargi ng f l oor
Tank f or l i qui d bul k
do not al l ow wei ght opt i mi zat i on of ADR t anks
Chassi s beam:
t wo prof i l es
one pl at e
Chassi s beam:
one si ngl e prof i l e
Al l oy, t emper
6005A T5/T6, 6082 T6
5083 H111/H34
5086 H111/H24
5456 H34
Si l o f or sol i d bul k Al l oy (O/H111 f or al l )
5083, 5086, 5383, 5454, 5754
5182, 5186, 5059, 5088
OTHER APPLICATIONS
Wheel s . . . . . . . . . . . . . . . . . . . . . . . . . . . 6061, 6082
Di esel f uel t anks . . . . . . . . . . . . . . . . . . . . . 5052, 5754
Tai l l i f t s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6005A
Fl oors . . . . . . . . . . . . . . . . . . . . . . . . 6082, 5086, 5754
Frami ng f or buses . . . . . . . . . . . . . . . . . . . .6060, 6005A
Si des & roof s f or buses . . . . . . . . . . . . . . . . .3003, 5005
Crash modul es . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6008
Bumper beams, crash boxes
& rol l over prot ect i ons . . . . . . . . . . . . . . . . . .7003, 7108
Suspensi on part s . . . . . . . . . . . . . . . . . . . . . . . . . .21100
St ruct ural component s-Hi nges-Support s . .42000, 42100
Compl ex shapes wi t h medi um st rengt h . . . . . . . .43000
Very compl ex shapes
wi t hout st ruct ural f unct i on . . . . . . . . . . . . . . . . . .44000
49
EUROPEAN ALUMINIUM ASSOCIATION
A lum inium alloys change their
m echanical and corrosion resist-
ance properties w hen subjected
to tem peratures other than
am bient tem perature. Tables V.6
& V.7 show the interrelationship
betw een service tem perature
and m echanical properties. In
Figure V.1 this is show n for one
alloy graphically.
7. Inf l uence of temperature
on mechani cal properti es
CHANGE IN MECHANICAL PROPERTIES OF 5086 O AFTER
HOLDING AT TEMPERATURE FOR 10,000 HOURS
Temperature Mechanical properties (*)
C° R
m
(MPa) R
p 0,2
(MPa) A%
-196 390 140 34
-80 280 120 26
-28 270 120 24
+20 270 120 22
+100 270 120 26
+150 210 110 35
+200 155 105 45
TABLE V.6
CHANGE IN MECHANICAL PROPERTIES OF 6082 T6 AFTER
HOLDING AT TEMPERATURE FOR 10,000 HOURS
Temperature Mechanical properties (*)
C° R
m
(MPa) R
p 0,2
(MPa) A%
-196 380 330 16
-80 330 295 13
-28 330 285 12
+20 320 285 12
+100 300 265 15
+150 240 220 18
+200 130 105 28
(*) M ean values. These properties are m easured at test tem perature.
TABLE V.7
50
R
m
-
R
p
0
,
2
M Pa
A
%
R
m
A %
R
p 0,2
-196 ° + 20 ° + 200 °
Tem perature °C
500
400
300
200
100
0
50
40
30
20
10
®®
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 50 | 51
7.2. Low and ver y l ow
t emper at ur es
C ontrarily to m ost other engi-
neering m etals, the m echanical
properties im prove at low tem -
peratures and especially the
elongation, w hich m akes alu-
m inium an ideal m etal for severe
w inter conditions and even
cryogenic applications (see
Figure V.1)
Further exam ples can be found in
standard EN 12392 “A lum inium
and alum inium alloys - W rought
products - Special requirem ents
for products intended for the pro-
duction of pressure equipm ent”.
CHANGE OF MECHANICAL CHARACTERITICS
AS A FUNCTION OF TEMPERATURE FOR
ALLOY 5086 O
FIGURE V.1
7.1. El evat ed
t emper at ur e
The loss in strength at higher
than am bient tem peratures is
negligible for tem peratures up
to 100°C (short tim e exposure)
or 80°C (long tim e exposure).
W hen subjected to even higher
tem peratures, then the loss in
m echanical properties is m oder-
ate for non-heat treatable alloys
in the O /H 111 tem per and for
heat treatable alloys in the
T1/T4 tem per.
The loss in m echanical proper-
ties at tem peratures above
100°C is very pronounced for
non heat treatable alloys in the
H 12, H 16 tem per as w ell as for
heat treatable alloys in the
T5/T6 tem per.
51
EUROPEAN ALUMINIUM ASSOCIATION
8.1. Wor k har deni ng of
non- heat t r eat abl e al l oys
H ardening is achieved by cold
deform ation, know n as w ork
hardening, that im proves the
physical properties and the hard-
ness of the m etal. It also reduces
the m etal’s capacity for deform a-
tion and its ductility (Figure V.2).
The greater the deform ation or
higher the w ork hardening rate,
the m ore pronounced is the
effect. It is also governed by the
com position of the m aterial.
The 5083 alloy, for exam ple,
w hich contains betw een 4 and
4.9% of m agnesium , acquires a
great hardness but its capacity
for deform ation is less than that
of the 5754 alloy w hich contains
betw een 2.6 and 3.6% M g.
W ork hardening is a general phe-
nom enon that takes place w hat-
ever the m ethod of deform ation
used: rolling, deep draw ing, fold-
ing, ham m ering, bending, press-
ing, etc. This m eans that it w ill
also occur during fabrication in
the w orkshop.
8. Inf l uence of f abri cati on
on the properti es of the al l oys
M Pa A %
R
m
A
R
p 0,2
Tem per 0 H 12 H 14 H 16 H 18
30
20
10
®
®
W ork hardening % 10 20 30 40 50 60 70 80
500
400
300
200
100
WORK HARDENING CURVE OF ALLOY 5083
FIGURE V.2
8.2. Sof t eni ng
by anneal i ng and r ecover y
It is possible to restore the ductil-
ity of the w ork hardened m etal by
heat treatm ent know n as
“annealing” (partial or full
annealing). In this process, w hich
takes place at tem peratures
betw een 150°C and 350°C , the
hardness and m echanical charac-
teristics of the m etal slow ly begin
to decrease: this is the recovery
phase [A -B] (Figure V.3). A t low er
annealing tem peratures this leads
to m edium -strength m aterial
properties. They then fall aw ay
m ore rapidly at high tem peratures
above 280 °C during recrystal-
lization [B-C ] and eventually
attain a m inim um value that cor-
responds to the m echanical char-
acteristics of the fully annealed
m etal [C -D ].
Restoration and annealing are
accom panied by a change in the
texture and size of the grains of
m etal observed under a m icro-
scope w ith X50 m agnification.
The texture can change from a
fibrous structure to a fully recrys-
tallized structure (Figure V.3).
The grain can grow in size during
recrystallization and annealing.
This grow th is revealed during
subsequent w orking, e.g. fold-
ing, by the rough “orange peel”
effect on the surface of the
m etal. G rain grow th above
around 100 m icrons reduces the
deform ation capacity of w ork
hardening alum inium alloys.
The follow ing conditions are
essential if a fine-grained annealed
structure is to be achieved:
• The m etal m ust have under-
gone a sufficient rate of defor-
m ation corresponding to a rela-
T - t
Ta
52
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 52 | 53
H
a
r
d
n
e
s
s
Recovery
Recrystallization
A nnealing
Tim e
A
C
B
D
O
HARDNESS CURVE DURING ANNEALING
FIGURE V.3
M icrographic view s
tive reduction in section of at
least 15% . This is “critical w ork
hardening”. If this condition is
not m et, then heat treatm ent
m ust be restricted to restoration
w ithout recrystallization,
• A rapid tem perature gradient
of 20 to 60°C per hour,
• Tem peratures over 350 to
380°C m ust be avoided,
• H olding tim es m ust be lim ited
to 2 hours m axim um .
For 5000 series alloys, annealing is
usually perform ed betw een 320°C
and 380°C for 30 to 120 m inutes.
Note: Non-heat treatable alloys in
the annealed temper (O, H111)
can only be brought to higher
strength by work hardening.
8.3. Heat t r eat abl e al l oys
If som e plastic deform ation m ust
be done on products of heat
treatable alloys, it should be car-
ried out in the T4 tem per; first the
allow able degree of deform ation
is bigger than for the T6 tem per
and second there is alm ost no
effect of w ork hardening. If for
the final product e.g. a bent
extrusion in a 6XXX alloy T6 tem -
per is needed, age hardening can
be carried out. Table V.8 gives an
indication how to proceed, using
typically a hot air furnace.
6000 SERIES ARTIFICIAL AGEING
Alloy Initial temper Artificial ageing Final Temper*
6060 T1 - T4 6 h at185°C T5 - T6
or 8 h at175°C
6005 T1 - T4 8 h at175°C T5 - T6
6106 T1 - T4 8 h at175°C T5 - T6
6061 T4 8 h at175°C T6
6082 T1 - T4 16 h at165°C
or 10 h at170°C T5 - T6
or 8 h at175°C
* T5, for an initial tem per of T1, T6 for an initial tem per of T4.
TABLE V.8 (typical)
53
EUROPEAN ALUMINIUM ASSOCIATION
8.4. Cast i ngs
C asting is the shortest path
from m olten m etal to the fin-
ished product. It is recom -
m ended for geom etrically-com -
plex parts. It is advantageous to
involve the foundry from the
conceptual phase into the
design process. The expert of
the foundry, know ing the plants
equipm ent, the process of m ak-
ing the m ould, the flow of m etal
into the m ould, the cooling and
shrinking of the cast piece etc.
can be of great help during the
design phase. W hen the design
of a casting is optim ized in view
of its production it is in m ost
cases possible for the foundry to
guarantee m uch better m echan-
ical properties than those listed
in standard EN 1706, especially
w ith respect to elongation.
The Table V.5 (see section 6.3)
m erits som e explanation.
The alloy 21100 needs very
careful design of the pieces w ith
respect to the casting process
and, in addition to that, the
m etal treatm ent in the foundry,
especially the degassing of the
m olten m etal, m ust be carried
out very carefully in order to
m inim ize m icro-porosity.
The index B or C in the colum n
“M achinability”has been put
because of the w earing of the
cutting tools due to the high sil-
icon content of the alloys.
The corrosion resistance of cast
pieces w ith the as-cast surface is
better than for m achined sur-
faces of the sam e piece due to
the m uch thicker oxide layer.
Desi gn of cast i ng par t s
G enerally speaking it is essential
to be aw are of production pos-
sibilities and lim itations from the
initial developm ent stage of a
new com ponent, not just in
term s of the choice of alloy and
casting technique but also in
term s of design. There are a
num ber of basic rules w hich
designers should follow :
• Sections should be kept uni-
form and thickness transitions
should be sm ooth, avoiding a
build-up of m etal at intersections
so as to reduce the risk of shrink-
age porosity during cooling,
• For the sam e reason, isolated
bosses should be avoided and
w alls m ust be correctly sized to
assist running,
• There should be a fillet at
every inside corner to avoid
cracking during the casting
operation (this is particularly
im portant for 21100 alloys),
• The filling design should be
som ew hat asym m etrical to
ensure controlled solidification
and uniform feed,
• The num ber of intersections
and undercuts should be kept to
a m inim um as they com plicate
tooling and the casting opera-
tion and hence increase the
cost. This applies equally to
deburring operations,
• The choice of dim ensional
tolerances m ust allow for the
casting technique and any sub-
sequent heat treatm ent defor-
m ation can occur during solu-
tion treatm ent and quenching.
Fl ywheel house cast i ng
f or t ruck engi ne (Brabant Al ucast )
54
ALUMINIUM IN COMMERCIAL VEHICLES CHA PTER V A LUM I N I UM A LLOYS FOR COM M ERCI A L VEHI CLES 54 | 55
9. Li st of standards
• EN 485 Aluminium and aluminium alloys – Sheet, strip and plate
Part 1: Technical conditions for inspection and delivery
Part 2: M echanical properties
Part 3: Tolerances on dim ensions for hot rolled products
Part 4: Tolerances on dim ensions for cold rolled products
• EN 515 Aluminium and aluminium alloys – Wrought products – Temper designations
• EN 573 Aluminium and aluminium alloys – Chemical composition and form of wrought products
Part 1: N um erical designation system
Part 2: C hem ical based designation system
Part 3: C hem ical com position
Part 4: Form s of products
• EN 755 Aluminium and aluminium alloys – Extruded rod/bar, tube and profiles
Part 1: Technical conditions for inspection and delivery
Part 2: M echanical properties
Part 3: Round bars, tolerances on dim ensions and form
Part 4: Square bars, tolerances on dim ensions and form
• EN 1706 Aluminium and aluminium alloys – Castings – Chemical composition and mechanical properties
• EN 12392 Aluminium and aluminium alloys – Wrought products – Special requirements for products
intended for the production of pressure equipment
• EN 14286 Aluminium and aluminium alloys – Weldable rolled products for the storage and transport
of dangerous goods
Registration record series Teal Sheets: International alloy designations and chemical composition limits
for wrought aluminium and wrought aluminium alloys available for free dow nload from the EA A w eb-
site: http://w w w .eaa.net/en/about-alum inium /standards/international-registration/
55
EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION
56
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57
2. POSSIBILITIES WITH ALUMINIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
3. SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
4. ALUMINIUM VERSUS STEEL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58
5. LIMIT STATE DESIGN . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
5. 1. Philosophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5. 2. What is the ultimate limit state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
5. 3. What is the serviceability limit state . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
6. SERVICEABILITY LIMIT STATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
7. ULTIMATE LIMIT STATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
7. 1. Cross section classes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
7. 2. Load bearing resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
7. 3. Welded connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69
7. 4. Bolted connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 73
8. FATIGUE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .76
8. 1. Theory . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
8. 2. Practice: comparison between good and bad chassis solutions . . . . . . . . . . . . . . 82
9. SPECIAL DESIGN ISSUES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
9. 1. Tanks for the transport of dangerous goods - ADR . . . . . . . . . . . . . . . . . . . . . . . . 86
9. 2. Tippers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
10. REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
CHAPTER VI
DESI GN AND CALCULATI ON
57
EUROPEAN ALUMINIUM ASSOCIATION
1. Introducti on
The new European design code
for alum inium structures is used
as a basis for this chapter. The
nam e of this standard is:
EN 1999 Eurocode 9: D esign of
alum inium structure
Part 1-1 G eneral structural rules
Part 1-2 Structural fire design
Part 1-3 Structures susceptible to
fatigue
Part 1-4 C old-form ed structural
sheeting
Part 1-5 Shell structures
Part 1-1 is used for all static
design and Part 1-3 for all
fatigue design show n in this
chapter.
A new European standard for the
execution of structural alum ini-
um is under developm ent and is
soon ready for publication. It is
recom m ended to use relevant
parts of this standard for execu-
tion of alum inium com ponents
for use in com m ercial vehicles.
The nam e of this standard is:
EN 1090-3: Execution of steel
structures and alum inium struc-
tures –Part 3: Technical require-
m ents for alum inium structures
2. Possi bi l i ti es
wi th al umi ni um
The advantages of designing
w ith alum inium are:
•H igh strength-to-w eight ratio
•Possibilities to create your ow n
cross-sections w ith the extrusion
technique
•G ood corrosion resistance
•Long vehicle life
•Easy to w ork w ith
•Easy to repair
Especially for product design, the
use of tailor-m ade profiles is a
great advantage for alum inium
com pared w ith other m etals. In
profile design the m aterial can be
placed w here the effect of the
m aterial is optim al regarding
resistance. D etails can be m ade
in such a w ay that it w ill ease the
fabrication and assem bling of
the com ponents.
3. Symbol s
Frequently used sym bols are
defined in this section:
f
o
characteristic value of 0.2 %
proof strength
f
u
characteristic value of ulti-
m ate tensile strength
f
ub
characteristic ultim ate tensile
strength of bolt
E m odulus of elasticity
d bolt diam eter
d
o
hole diam eter
t w all thickness
A cross section area
W section m odulus
γ
M
partial safety factor for resist-
ance (see the definitions in sec-
tion 5.2), in EN 1999-1-1:
Subscript
Ed
is used for factored
load effects. It m ay be on axial
force (N
Ed
), bending m om ent
(M
Ed
), shear force (V
Ed
), torsion
(T
Ed
) and forces in connection
w ith bolted connections (F
v,Ed
for
shear force and F
t,Ed
for tension
force).
58
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 58 | 59
Both steel and alum inium are
m etals w ith relatively high
strength. Both m aterials are
incom bustible and w ill not con-
tribute to a fire. For structural
purposes the m ain differences
are:
Elasticity: The m odulus of elas-
ticity (E-m odulus) of alum inium is
1/3 of that of steel. This m eans
that an alum inium beam w ith
the sam e cross-section and the
sam e loads as a steel beam w ill
have a deflection 3 tim es that of
the steel beam .
Weight: The density of alum ini-
um is 1/3 of that of steel. This
m eans that a steel beam w ill
w eigh 3 tim es m ore than an alu-
m inium beam w ith the sam e
cross-section.
Welding: W hen w elding a hard-
ened alum inium alloy som e of
the hardening effects w ill be lost.
The strength in the heat affected
zone (H A Z) w ill be reduced. This
reduction depends on the alloy,
tem per, type of product and
w elding procedure. O rdinary
steel has no strength reduction
after w elding.
Thermal elongation: The coef-
ficient of therm al elongation of
alum inium is tw ice that of steel.
This m eans that an alum inium
m em ber w ill get tw ice the ther-
m al elongation as a sim ilar steel
m em ber w ith the sam e tem pera-
ture difference. Since the elastic
m odulus of alum inium is 1/3 of
steel, the stresses in an alum inium
m em ber w ith fixation are 2/3 of
that in a sim ilar steel m em ber.
M ost of the structural alum inium
alloys have relatively high
“strength-to-E m odulus” ratio.
This effect is especially clear
w hen the alum inium alloy is
strain-hardened or heat-treated.
Structural alum inium alloys have
roughly tw ice the “strength-to-E
m odulus”ratio than standard steel.
H ow ever, w hen com pared w ith
high strength steels, structural
alum inium alloys have about the
sam e “strength-to-E m odulus”
ratio. It should also be noted that
the elastic m odulus of an alloy
m ainly depends on its parent
m etal. In other w ords, all alu-
m inium alloys have very sim ilar E-
m odulus, but this is also valid for
steel alloys. C onsequently, the so
called “high strength steels”
don’t have better elastic proper-
ties than m ild steel.
Steel designers often use the
strength of the m aterial as gov-
erning criteria w hen designing a
steel structure and check after-
w ards w hether the deflection is
w ithin the requirem ent.
W hen designing an alum inium
structure, it w ill often be the
deflection criterion that w ill be
governing. For that reason, the
design procedure w ill start w ith
the deflection criterion and it w ill
be checked afterw ards if the
stress or the resistance of the
structure is w ithin the lim its.
The deflection of m em bers under
bending load depends on the
m odulus of elasticity (E) and on
the m om ent of inertia (I) togeth-
er w ith the load and the span.
W ith the sam e span and load, it
w ill be the product E x I that w ill
determ ine the deflection.
To get the sam e deflection of
steel and alum inium beam s in
bending, the m om ent of inertia
of the alum inium beam m ust be
three tim es that of steel. If the
increase in the m om ent of inertia
is to be done only by increasing
the thickness of the w eb and
flanges, the alum inium beam w ill
have the sam e w eight as the
steel beam .
4. Al umi ni um versus Steel
59
EUROPEAN ALUMINIUM ASSOCIATION
To save w eight, the alum inium
beam s in bending have to be
higher. A n exam ple w ill illustrate
this:
A n alum inium beam shall have
the sam e deflection as an IPE
240 steel beam . The m om ent of
inertia and the m ass of the IPE
240-beam are
I = 38.9 · 10
6
m m
4
.
m ass = 30.7 kg/m .
The alum inium beam m ust have
a m om ent of inertia of
I =116.7 · 10
6
m m
4
to get the sam e deflection.
If the height of the alum inium
alloy beam shall be 240 m m , this
w ill be satisfied by an I-beam of
I 240 x 240 x 12 x 18.3
w hich has a m om ent of inertia
and the m ass of
I = 116.6 · 10
6
m m
4
m ass = 30.3 kg/m
If the height of the alum inium
alloy beam can be 300 m m , the
deflection criteria w ill be satisfied
by an I 300 x 200 x 6 x 12.9
w hich has a m om ent of inertia of
I = 116.7 · 10
6
m m
4
and a m ass =18.4 kg/m
w hich is a w eight saving of 40% .
A n I 330 x 200 x 6 x 10 w ill have
a m om ent of inertia of
I = 117.3 · 10
6
m m
4
and a m ass = 15.8 kg/m
w hich give a w eight saving of 49% .
These three different alum inium
beam s w ill give the sam e deflection
as an IPE 240 steel beam . It w ill be
the shape and stability of the beam
that w ill determ ine the w eight of
the beam . Table VI.1 show s the
beam s and the w eight savings.
®
®
®
®
®
®
t
h
®
®
w
b
Steel Aluminium Aluminium Aluminium
M om ent in inertia in m m
4
38.9 10
6
116.6 10
6
116.7 10
6
117.3 10
6
E x I (N /m m
2
) 8.17 10
12
8.16 10
12
8.17 10
12
8.21 10
12
h (m m ) 240 240 300 330
b(m m ) 120 240 200 200
w (m m ) 6.2 12 6 6
t (m m ) 9.8 18.3 12.9 10
U nit w eight (kg/m ) 30.7 30.3 18.4 15.8
W eight in %
of the steel beam 100 % 99 % 60 % 51 %
TABLE VI.1
60
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 60 | 61
The stress in an alum inium struc-
ture designed according to
deflection criteria is very often
low . In the follow ing exam ple a
steel beam , IPE 240 is com pared
w ith an alum inium beam I 330 x
200 x 6 x 10 (both beam s are
show n in the table VI.1). The
deflection criterion is 1/250 of
span (24 m m ), the span is 6000
m m and the load is 11.6 kN /m . In
the Figure VI.1. the stress-strain
curves for steel S355 and alu-
m inium EN A W -6082 T6 is
show n. The stress and strain for
both the steel and alum inium
beam is also show n. W ith the
sam e deflection, the sam e load
and the sam e span, the steel
beam has a bending stress of
161 M Pa w hile the alum inium
beam has a bending stress of 73
M Pa. This is the m axim um stress
w hen the deflection is 24 m m for
both beam s.
EN AW-6082 T6
S355
0,1 0,2 0,3 0,4 0,5 0,6 0,7
®
300
200
100
STRESS COMPARISON BETWEEN ALUMINIUM AND STEEL BEAMS
FIGURE VI.1
0
,
1
0
5
0
,
0
7
7
161
73
σ
(
M
p
a
)
®
ε (% )
A dditional com parison of w eight-optim ized beam s are also given in
C hapter III, section 2.1
61
EUROPEAN ALUMINIUM ASSOCIATION
5.1. Phi l osophy
Lim it state design and partial
safety factor m ethod are the
m ethods that the new design
standards are based on. In
Europe the EN 19xx standards
are the basis for this m ethod for
all structural m aterials in civil
engineering. For alum inium the
actual standards are:
EN 1990 Eurocode –Basis for structural design
EN 1991 Eurocode 1 –A ctions on structures. A ll parts
EN 1999 Eurocode 9 –D esign of alum inium structures
5. Li mi t state desi gn
EN 1990 gives the partial safety
factor on loads and rules for
com bination of loads to give the
different action effects.
EN 1991 gives the characteristic
loads for structures and buildings
such as self w eight, live loads,
w ind loads, snow loads, traffic
loads etc.
EN 1999 gives the design rules
for alum inium structures.
The ultimate limit state is the
condition w here the safety of the
structure is calculated. A struc-
ture shall not collapse and design
in accordance w ith the ultim ate
lim it state shall avoid structural
failure.
The partial safety factor for the
resistance (γ
M
) shall take care of
the scattering of the strength
properties and the geom etry of
the cross section. For connec-
tions the partial safety factor
shall in addition take care of
uncertainties in the w elds and in
the bolts and bolt configuration.
The partial safety factor for the
load effects (γ
F
) shall take care of
the scattering of the determ ina-
tion of the loads and the proba-
bility in the com bination of dif-
ferent loads. The partial safety
factor is different for the differ-
ent types of loads, their certainty
and how they are com bined.
D ead loads (i.e. self w eight of
structure) have a low partial safe-
ty factor w hile the live load (i.e.
all forces that are variable during
operation, e.g. w eight of goods,
road vibrations etc…) has a high-
er partial safety factor.
5.2. What i s t he ul t i mat e
l i mi t st at e
62
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 62 | 63
The condition to be fulfilled is:
R
k
≥ γ
F
.
E
k
γ
M
w here:
R
k
is the characteristic value of
the resistance; it m ay be axial
tension or com pression, bending
m om ent, shear or a com bined
resistance.
E
k
is the characteristic value of
the load effects; it m ay be axial
tension or com pression, bending
m om ent, shear or a com bined
load effect on a cross section or a
connection.
γ
M
is the partial safety factor for
the resistance, also often called
m aterial factor.
γ
F
is the partial safety factor for
the load effects, also often called
load factor.
This relation is show n in the
Figure VI.2.
Typical values for the partial safe-
ty factor for the resistance are
1.10 (g
M1
) for m em bers and 1.25

M2
and γ
Mw
) for bolt and rivet
connections and w elded connec-
tions. These are the m aterial fac-
tors for building and civil engi-
neering and m ay also be used in
all structural design because the
m aterial, the geom etrical dim en-
sions and the fabrication of con-
nections are alm ost sim ilar in all
alum inium structures.
®
FIGURE VI.2
F
r
e
q
u
e
n
c
y
®
The serviceability lim it state is
the condition w here the service-
ability criteria have to be satis-
fied. The m ost used serviceability
criteria are:
•D eflection lim its in all directions
•D ynam ic effects like vibrations
In serviceability lim it states both
the partial safety factor for the
resistance (g
M
) and the partial
safety factor for the load effects

F
) are 1.0.
Typical values for the load effect
factors in buildings and civil engi-
neering are 1.2 for dead loads
and 1.5 for live loads. For design
of com ponents for com m ercial
vehicles the follow ing load fac-
tors m ay be used:
D ead load: 1.1
Live load: 1.5
E
k
R
k E
k
.
γ
F
<
R
k
γ
M
5.3. What i s t he ser vi ceabi l i t y l i mi t st at e
63
EUROPEAN ALUMINIUM ASSOCIATION
A ll calculations in serviceability
lim it state are elastic calculations.
Elastic deform ations are calculat-
ed and com pared w ith the lim its
for deflections. The sizes of vibra-
tions have to be calculated in the
sam e m anner. If the vibration has
a high num ber of cycles, the
m em bers and the connection
details have to be checked for
fatigue.
N orm ally the calculations of elas-
tic deflections are based on the
m om ent of inertia for the gross
cross-section of the m em ber. For
m em bers in cross-section class 4
(see section 7.2.4 in EN 1999-1-1)
it is necessary to reduce the
m om ent of inertia, if the stresses
of the com pression part of the
cross section are higher than the
stresses w hen local buckling
occurs.
M om ent of inertia for calculation
of deflections for cross section
class 4 m em bers:
I
ser
= I
gr
-
σ
gr
(I
gr
- I
eff
)
f
o
W here:
σ
gr
is m axim um com pressive
stress in serviceability lim it state
in the cross section, based on the
gross cross-section properties
(positive in the form ula)
I
gr
is the m om ent of inertia for
the gross cross-section
I
eff
is the m om ent of inertia of the
effective cross-section in ultim ate
lim it state, w ith allow ance for
local buckling
7.1. Cr oss sect i on cl asses
C ross-sections are classified in 4
classes. In Table VI.2 the differ-
ent classes identify how the
cross-section behaves during
com pression and bending. This
is directly linked to the resistance
(load bearing capacity) of the
cross-section.
Thin parts of a cross-section m ay
buckle at low stresses, and this
w ill reduce the resistance of the
cross-section. This is taken care
of w ith the rules for cross-section
classification.
6. Servi ceabi l i ty l i mi t state 7. Ul ti mate
l i mi t state
64
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 64 | 65
Class 1 Class 2 Class 3 Class 4
Cross-sections that can
form a plastic hinge w ith
the rotation capacity
required for plastic analy-
sis w ithout reduction of
the resistance.
C ross-section that can
develop their plastic
m om ent resistance, but
have lim ited rotation
capacity.
C ross-section w here the
calculated stress in the
extrem e fibre of the alu-
m inium m em ber can
reach its proof strength.
Cross-section that w ill get
local buckling before
attainm ent of proof stress
in one or m ore parts of
the cross-section.
The resistance m ay be
calculated on the basis
of plastic behaviour tak-
ing the m aterial harden-
ing effect into account.
Rules are given in EN
1999-1-1. A nnex F.
The resistance m ay be
calculated on the basis
of perfectly plastic
behaviour for the m ate-
rial using the conven-
tional elastic lim it as the
lim it value. Rules are
given in EN 1999-1-1.
A nnex F. The resistance
is calculated on the
basis of elastic design.
The resistance is calculat-
ed on basis of an effec-
tive cross-section. Rules
for calculating the effec-
tive cross-section are
given in EN 1999-1-1,
6.1.5
EN 1999-1-1, 6.1.4 gives rules
how to classify any cross-section.
A β value (i.e. w idth to thickness
ratio) is calculated as:
β = η
.
b
t
w here:
b = the w idth of a cross-section
part
t = the corresponding thickness
η = a value depending on the
stress situation and if the part is
an outstand or an internal cross-
section part
Lim its are given for the β value
for the different classes and for
w elded or unw elded parts and
for outstand or internal parts.
M ost alum inium structures in
com m ercial vehicles w ill be opti-
m ised regarding w eight. C ross
section classes 1 and 2 w ill there-
fore seldom be used. Elastic
design in cross section class 3 and
4 w ill be the norm al situation.
TABLE VI.2
7.2. Load beari ng resi st ance
The load bearing resistance shall
alw ays be higher than the fac-
tored load effects.
EN 1999-1-1 gives rules for cal-
culating the load bearing resist-
ances for different kinds of m em -
bers exposed by different load
effects. In the Table VI.3, som e of
these rules are listed, and refer-
ences are given:
65
EUROPEAN ALUMINIUM ASSOCIATION
Situations Ref. EN 1999-1-1 Resistance
Tension 6.2.3 The sm aller of:
N
o,Rd
=
A
g
. f
o
, N
u,Rd
=
0,9 . A
net
.
f
u
or N
u,Rd
=
A
eff
.
f
u
γ
M1
γ
M 2
γ
M 2
N
o,Rd
is the design resistance to general yielding.
N
u,Rd
is the design resistance to axial force of the net cross-section
at holes for fasteners or the effective cross-section at w elds.
A
g
is the gross cross-section.
A
net
is the net area of cross-section.
A
eff
is the effective area of cross-section taking the H A Z effects
into account.
C om pression
(w ith no
buckling)
6.2.4 The sm aller of:
N
u,Rd
=
A
net
. f
u
, N
c,Rd
=
A
eff
.
f
o
γ
M2
γ
M1
N
u,Rd
is the design resistance to axial force of the net cross-section
at holes for fasteners.
N
c,Rd
is the design resistance to axial force at each cross-section.
A
net
is the net section area w ith deduction for holes and if required
the effects of H A Z softening at the cross section w ith holes.
A
eff
is the effective section area based on the reduced thickness
allow ing for the effect of local buckling.
Bending
m om ent
6.2.5
6.2.5.2
6.2.5.1
Bending m om ent resistance in a net section:
M
u,Rd
=
W
net
. f
u
γ
M2
Bending m om ent resistance in each cross section:
M
c,Rd
=
α
.
W
el
. f
o
γ
M1
W
net
is the elastic m odulus of the net section allow ing for holes
and H A Z softening.
W
el
is the elastic m odulus of the gross section.
α is the shape factor given in table 6.4 in EN 1999-1-1, 6.2.5.
Shear 6.2.6
6.7.4 6.7.5
6.7.6
The design value for shear resistance for non-slender sections:
V
Rd
=
A
V
. f
o
√3 .γ
M1
A
v
is the shear area.
For slender w ebs and stiffened w ebs the rules for capacity of plate
girder w ebs have to be used (plate buckling).
TABLE VI.3
66
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 66 | 67
Situations Ref. EN 1999-1-1 Resistance
Torsion 6.2.7
6.2.7.2
6.2.7.3
The design St. Venants torsion m om ent resistance w ithout w arping:
T
Rd
=
W
T,pl
. f
o
√3 .γ
M1
W
T,pl
is the plastic torsion m odulus
For torsion w ith w arping the capacity is the sum of tw o internal
effects. For com bined shear force and torsional m om ent the
capacity is given by a reduced shear capacity.
Bending and
shear
6.2.8 The shear force w ill reduce the m om ent resistance. If the shear
force is less than half of the shear force resistance, the effect
of the m om ent resistance is so sm all that it can be neglected.
Bending and
axial force
6.2.9
6.2.9.1
6.2.9.2
6.2.9.3
Form ulae are given for the com bined effect of an axial tension
and bending m om ents about one or tw o axis for:
•open cross-sections
•hollow sections and solid cross-sections
•m em bers containing localized w elds
Bending, shear
and axial force
6.2.10 The shear force w ill reduce the com bined axial tension and
m om ent resistance. If the shear force is less than half of the shear
force resistance, the effect of the com bined axial tension and
m om ent resistance is so sm all that it can be neglected.
W eb bearing 6.2.11 This is for design of w ebs subjected to localized forces caused
by concentrated loads or reactions applied to a beam .
C om pression
(buckling
resistance)
6.3 M em bers subject to axial com pression m ay fail in one of the
three w ays listed below :
•flexural
•torsional or flexural torsional
•local squashing
The design buckling resistance of a com pression m em ber is:
N
b,Rd
=
κ
.
χ
.
A
eff
.
f
o
γ
M1
κ is a factor to allow for effect of the H A Z at w elds
χ is the reduction factor for the relevant buckling m ode
A
eff
is the effective area of the cross section. (For cross section class
1, 2 and 3 this is the gross cross-section, for cross section class 4
it is reduced for local buckling effects)
67
EUROPEAN ALUMINIUM ASSOCIATION
Situations Ref. EN 1999-1-1 Resistance
M em bers
in bending
and axial
com pression
6.3.3
6.3.3.1
6.3.3.2
6.3.3.3
6.3.3.4
6.3.3.5
M em bers subject to bending and axial com pression m ay fail in one of
the tw o w ays listed below :
•flexural buckling
•lateral-torsional buckling
C om bination form ulas are given for m em bers w ith axial
com pression in com bination w ith bending about one or tw o axis
and fail for flexural buckling. These form ulas are given for:
•open double sym m etric cross-section
•solid cross-section
•hollow cross-section and tube
•open m ono-sym m etrical cross-section
C om bination form ula for open cross-section sym m etrical about
m ajor axis, centrally sym m etric or double sym m etric cross-section
is given for lateral- torsional buckling.
Form ulas are also given for calculation of the follow ing effects:
•m em bers containing localized w elds
•m em bers containing localized reduction of cross-section
•unequal end m om ents and/or transverse loads
Plate girders 6.7
6.7.2 & 6.7.3
6.7.4 & 6.8
6.7.6
6.7.5
6.7.7
6.1.5
6.3.2
A plate girder is a deep beam w ith a tension flange, a com pression
flange and a w eb plate. The w eb is usually slender and m ay be
reinforced by transverse or/and longitudinal stiffeners.
W ebs buckle in shear at relatively low applied loads, but considerably am ount
of post-buckled strength can be m obilized due to tension field action.
Plate girders are som etim es designed w ith transverse w eb reinforcem ent
in form of corrugations or closely-spaced transverse stiffeners (extrusions).
Plate girders can be subjected to com binations of m om ent, shear
and axial loading, and to local loading on the flanges. Because
of their slender proportions they m ay be subjected to lateral
torsional buckling, unless properly supported along the length.
Failure (buckling) m odes m ay be:
•w eb buckling by com pressive stresses
•shear buckling
•interaction betw een shear force and bending m om ent
•buckling of w eb because of local loads on flanges
•flange-induced w eb buckling
•torsional buckling of flange (local buckling)
•lateral torsional buckling
68
7.3. Wel ded connect i ons
7.3.1. General
The rules given in EN 1999-1-1,
clause 8.6, apply to structures
w elded by M IG or TIG and w ith
w eld quality in accordance w ith
EN 1090-3. C ertified w elders are
highly recom m ended.
Recom m ended w elding consum -
ables can be found in:
•C hapter VIII, section 3.8
•EN 1999-1-1, section 3.3.4
•EN 1011-4
W hen w elding hardened alu-
m inium alloys, part of the hard-
ening effect w ill be destroyed. In
a w elded connection it can be
three different strengths:
•the one of the parent (not
heat affected) m aterial (f
o
)
•the one in the heat affected
zone (f
o,HAZ
)
•the one of the w eld m etal (f
w
)
N orm ally it w ill be necessary to
check the stresses in the H A Z and
in the w elds.
The strength in H A Z is depend-
ent on the alloy, the tem per, the
type of product and the w elding
procedure. Values are given in
Table 3.2 in EN 1999-1-1.
The strength in the w eld (w eld
m etal) is dependent on the filler
m etal (w elding consum ables)
and the alloys being w elded.
Values are given in Table 8.8 in
EN 1999-1-1.
Single sided butt w elds w ith no
backing is practically im possible
to w eld in alum inium . If single
sided butt w elds cannot be
avoided, the effective seam
thickness can be taken as:
•the depth of the joint prepara-
tion for J and U type
•the depth of the joint preparation
m inus 3 m m or 25% , w hichever is
the less for V or bevel type
In addition to the single sided
butt w eld, a fillet w eld m ay be
used to com pensate for the low
penetration of the butt w eld.
W hen designing a w elded connec-
tion som e few practical precautions
should be taken into account.
•Provide good access to the
w elding groove. The “w elding
head”of the equipm ent used for
w elding alum inium is rather
large, so there m ust be enough
space around the w eld.
•G ood access is also needed for
checking the w eld. A ll w elds
shall be 100 % visually exam ined
in addition to som e non-destruc-
tive testing (N D T).
•Full penetration single sided
butt w elds are im possible to
w eld w ithout any backing.
If possible, position the w elds in
areas w here the stresses are low .
7.3.2. Butt weld
H eavy loaded m em bers should be
w elded w ith full penetration butt
w elds. The effective thickness of
a full penetration butt w eld
should be taken as the thickness
of the thinnest connecting m em -
ber. The effective length should
be taken as the total length if
run-on and run-off plates are
used. If not, the total length
should be reduced by tw ice the
effective thickness. (Figure VI.3)
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 68 | 69
®
®
®
®b
t
F,σ
F,σ
®
®
®
®b
t
F,τ
F,τ
Butt w eld subject to norm al stresses
Butt w eld subject to shear stresses
FIGURE VI.3
69
EUROPEAN ALUMINIUM ASSOCIATION
D esign form ulas for butt w elds:
N orm al stress, tension or com -
pression, perpendicular to w eld
axis:
σ


f
w
γM
w
Shear stress:
τ ≤ 0,6
.
f
w
γM
w
C om bined norm al and shear
stress:
√σ
2

+ 3
.
τ
2

f
w
γM
w
7.3.3. Fillet weld
A fillet w eld is defined w ith the
throat thickness “a”given in m m .
The Figure VI.4 show s how to
m easure the throat thickness.
The effective length should be
taken as the total length of the
w eld if:
•the length of the w eld is at
least 8 tim es the throat thickness
•the length of the w eld does
not exceed 100 tim es the throat
thickness w ith a non-uniform
stress distribution
•the stress distribution along
the length of the w eld is constant
FIGURE VI.4
®
®
®
®
®
®
t
1
®
®
t
2
g
1
®
®
a
a
®
®
a
pen
EXAMPLE OF UNIFORM STRESS DISTRIBUTION
FIGURE VI.5
EXAMPLE OF NON UNIFORM STRESS DISTRIBUTION
FIGURE VI.6
τ τ
τ τ
70
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 70 | 71
The forces acting on a fillet w eld
shall be resolved into stress com -
ponents w ith respect to the
throat section (see Figure VI.7).
These com ponents are:
σ

: norm al stress perpendicular
to the throat section
σ

: norm al stress parallel to the
w eld axis
τ

: shear stress acting on the
throat section perpendicular to
the w eld axis
τ

: shear stress acting on the
throat section parallel to the
w eld axis
D esign form ula for fillet w eld:
√σ
2

+ 3
.

2

+ τ
2
II
) ≤
f
w
γM
w
®
®
®
®®
FIGURE VI.7
σ

®
σ
II
F,σ
a
®
®
τ
II
τ τ

71
EUROPEAN ALUMINIUM ASSOCIATION
7.3.4. Heat affected zone
The stress in the heat affected
zone has to be checked. The
stress is calculated for the sm all-
est failure plane for both butt
w elds and fillet w elds. The
sketches below (ref. BS 8118)
indicate the failure plane for
som e w elds (Figures VI.8, VI.9,
VI.10, VI.11):
W : w eld m etal, check of w eld
F: heat affected zone, check of
fusion boundary
T: heat affected zone, check of
cross section
BUTT WELD
FIGURE VI.8
®
®
®
®
®
®
t
F W F
P
v
P
a
P
v
P
a
T BUTT WELD
FIGURE VI.10
T FILLET WELD
FIGURE VI.11
®
®
P
v
P
a
®
®
P
v
P
a
®
®
W
F
T
t
F
®
®
t
FILLET WELD
FIGURE VI.9
®
®
t
®
®
P
v
P
a
T
T T
F
W
®
®
t
®
®
P
v
P
a
T
T T
F
W W
F
F F
72
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 72 | 73
7.4. Bol t ed connect i ons
The rules for bolted connections are
given in EN 1999-1-1, clause 8.5.
M inim um , regular and m axim um
spacing, end and edge distances
for bolts are given in the Table
VI.4.
Minimum Regular Maximum
e
1
= 1.2
.
d
0
e
2
= 1.2
.
d
0
p
1
= 2.2
.
d
0
p
2
= 2.2
.
d
0
e
1
= 2.0
.
d
0
e
2
= 1.5
.
d
0
p
1
= 2.5
.
d
0
p
2
= 3.0
.
d
0
e
1
= 4
.
t + 40mm
e
2
= 4
.
t + 40mm
p
1

{
14
.
t
200mm
p
2

{
14
.
t
200mm
p
1
= 2.2
.
d
0
p
2
= 2.4
.
d
0
p
1
= 2.5
.
d
0
p
2
= 3.0
.
d
0
p
1

{
14
.
t
200mm
p
2

{
14
.
t
200mm
p
1
= 2.2
.
d
0
p
1
= 2.5
.
d
0
O uter lines:
p
1

{
14
.
t
200mm
Inner lines:
p
1

{
28
.
t
400mm
The m axim um clearance for fit-
ted bolts is 0.3 m m and for non-
fitted bolts 1.0 m m .
Failure m odes for bolted connec-
tions m ay be:
•block tearing, failure in shear
in a row of bolts along the shear
face of a bolt group and tension
failure along the tension face of
the bolt group
•shear failure in the bolt
•bearing failure of the bolt hole
•tension failure of the bolt
•punching shear around the
bolt head or nut
•com bined shear and tension
failure
o)outer line i)inner line
d
0
is the diam eter of the hole and t = thickness of the plate
TABLE VI.4
73
EUROPEAN ALUMINIUM ASSOCIATION
Failure mode Formula Parameters
Shear
resistance per
shear plane
F
v,Rd
=
α
v
. f
ub
. A
γ
M2
α
v
= 0.6 for steel bolts, 4.6, 5.6 and 8.8
α
v
= 0.5 for steel bolts, 4.8, 5.8, 6.8 and 10.9
α
v
= 0.5 for stainless steel and alum inium bolts
A is the cross-section of the bolt at the shear plane
Bearing
resistance F
b,Rd
=
k
1
. α
b
. f
u
. d . t
γ
M2
k
1
= smallest of
2.8
e
2
- 1.7
d
0
{
2.5
for edge bolts
k
1
= smallest of
1.4
p
2
- 1.7
d
0
{
2.5
for inner bolts
α
b
= smallest of
α
d
f
ub
f
u
{
1.0
α
d
=
e
1
for end bolts
3 . d
0
α
d
=
p
1

1
for inner bolts
3 . d
0
4
Tension
resistance
F
t,Rd
=
k
2
. f
ub
. A
s
γ
M2
k
2
= 0.9 for steel bolts
k
2
= 0.5 for alum inium bolts
k
2
= 0.63 for countersunk steel bolts
A
s
is the tensile stress area of the bolt
Punching shear
resistance
B
p,Rd
=
0,6 . π . d
m
. t
p
. f
u
γ
M2
d
m
is the m ean of across points and across flats
of a bolt head or the nut or the outer
diam eter of the w asher
t
p
is the thickness of the plate under the bolt head
or the nut
C om bined
shear
and tension
F
v,Ed
+
F
t,Ed
≤ 1.0
F
v,Rd
1.4
.
F
t,Ed
F
v,Ed
is the load effect of shear
F
t,Ed
is the load effect of tension
TABLE VI.5
74
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 74 | 75
C onnection details that carry ten-
sile forces, and w here the tensile
forces don’t go directly through
the bolts, additional forces in the
bolts have to be accounted for.
These forces are called prying
forces (Q ) and they can be con-
siderable large. See the figure
VI.12.
FIGURE VI.12
N = F
N
+ Q N = F
N
+ Q
Q
Q
2 F
N
Truck bodi es f or beverage t ransport
75
EUROPEAN ALUMINIUM ASSOCIATION
8.1. Theor y
Structures w ith repeating loads
m ay be susceptible to fatigue
w hen the num ber of load cycles
is high, even w hen the loads give
low stresses in the structure.
Fatigue failure starts w ith devel-
opm ent of a crack at a point w ith
stress concentrations. W ith con-
tinuous repeating loads the crack
w ill grow , this w ill be show n as
one striation in the failure sur-
face for each load cycles. The dis-
tance betw een the striations is
depending on the stress range
and that is giving the grow ing
speed. The stress range is
defined as the algebraic differ-
ence betw een the stress peak
and the stress valley in a stress
cycle. A t low stress ranges the
crack grow s slow ly and w ith high
stress range it grow s fast. (Figure
VI.5)
8. Fati gue
Trai l er f at i gue t est i ng i n l aborat ory (Benal u)
76
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 76 | 77
Rules for fatigue design are given
in EN 1999-1-3. The rules are
based on quality levels given in
EN 1999-1-3 and EN 1090-3.
•The fatigue strength depends on:
•type of detail (design)
•stress range
•num ber of cycles
•stress ratio
•quality of m anufacturing
FIGURE VI.13
®
®
®
®
®
®
®
®
®
®
®
®
σ
σ
m ax
σ
m
σ
m in
3
1
2
T
0
σ
3
σ
3
∆
σ
1. Stress peak
2. Stress valley
3. Stress cycle
∆σ Stress range
σ
3
Stress am plitude
The pict ure is showing t he st riat ions in a fat igue failure surface of an aluminium t ube.
77
EUROPEAN ALUMINIUM ASSOCIATION
The properties of the parent
m aterial have very little influence
on the fatigue strength in practi-
cal structures and com ponents.
For connections the properties of
the parent m aterial have no
influence at all. For a plate or
extrusion w ith no m anufacturing
or only holes and notches the
standard deviate betw een EN
AW 7020 and all other structural
alloys.
The fatigue strength is given as
SN curves for the different
details. A ll detail categories given
in EN 1999-1-3 have their ow n
SN curve. A typical SN curve is
show n on the Figure VI.14.
1). N um ber of cycles (10
8
) at
w hich the cut-off lim it is defined
2). For low cycles fatigue, this
part of the curve m ay not be cor-
rect, other calculation m ethods
are recom m ended (A nnex F of
EN 1999-1-3). It shall be checked
that the m axim um design stress
range don’t result in a tensile
stress exceeding the design stress
in ultim ate lim it state.
FIGURE VI.14
10
4
10
5
10
6
10
7
10
8
10
9
N
2)
a
c
d m
2
1
b
1
m
1
N
L
1)
®
®
® 2
.
10
e
N
C
5
.
10
e
N
D
∆σ
∆σ
C
∆σ
D
∆σ
L
a. Fatigue strength curve b. Reference fatigue strength c. C onstant am plitude fatigue lim it d. C ut-off lim it
S
78
5.1 63-4,3
C ontinuous
autom atic
w elding
B C
5.2 56-4,3 C C
5.3 45-4,3
A ny backing
bars to be
continuous
C D
5.4 45-4,3 B C
5.5 40-4,3 C D
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 78 | 79
The stress ratio, R, is the m ini-
m um stress divided by the m axi-
m um stress in a constant am pli-
tude stress history or a cycle
derived from a variable am pli-
tude stress history. Favourable
stress ratio w ill enhance the
fatigue strength for som e cases
com pared w ith the values given
in the standard. For initiation
sites in base m aterial aw ay from
connections, there w ill be an
increase in the fatigue strength
for R < +0.5. For initiation site at
w elded or m echanical fastened
connections in sim ple structural
elem ents, w here the residual
stresses has been established,
taking into account any preac-
tion or lack of fit, there w ill be an
increase in the fatigue strength
for R < -0.25. For other cases
there w ill be no change from the
values in the standard.
Som e typical details categories
are show n in the Table VI.6. The
first row in the table gives the
detail type num ber, the second
row gives the detail category, the
third gives a sketch of the detail
and also show ing the initiation
site and the direction of the
stress, the fourth gives the w eld
type, the fifth gives the stress
param eter, the sixth gives stress
concentrations already allow ed
for, the seven gives the w elding
characteristics, the eight gives
the quality level for the internal
im perfections and the ninth gives
the quality level for the surface
and geom etrical im perfections.
The requirem ents for the quality
levels are found in EN ISO 10042
and additional requirem ents are
given in EN 1090-3.
TABLE VI.6
N
o
m
i
n
a
l

s
t
r
e
s
s

a
t

i
n
i
t
i
a
t
i
o
n

s
i
t
e
Full penetration
butt w eld
W eld caps ground
flush
Full penetration
butt w eld
C ontinuous fillet
w eld
A t w eld discontinuity
A t w eld discontinuity
A t w eld discontinuity
∆σ
®
®
®
®
®
®
∆σ
∆σ
®
®
∆σ
®
®
®
®
∆σ
®
®
∆σ
®
®
®
®
79
EUROPEAN ALUMINIUM ASSOCIATION
D etail types 5.4 and 5.5 are an
exam ple w here the sam e detail
has different fatigue strength
depending on the quality of the
w eld.
The SN curves that correspond to
these detail categories are show n
on Figure VI.15.
The num erical values for the
sam e curves are show n in the
Table VI.7 :
INFLUENCE OF WELD QUALITY ON FATIGUE STRENGTH
FIGURE VI.15
500
400
300
200
150
100
50
40
30
20
15
10
5
∆σ
N /m m
2
N
C
N
O
N
L
10
4
10
3
10
6
10
7
10
8
10
9
63-4,3
56-4,3
45-4,3
40-4,3
36-4,3
28-4,3
S
N
80
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 80 | 81
SLOPE Cycles N
m
1
m
2
1E+05 1E-06 2E+06 5E+06 1E+07 1E+08 1E+09
4,3 6,3 126,4 74,0 63,0 50,9 45,6 31,6 31,6
4,3 6,3 112,4 65,8 56,0 45,3 40,5 28,1 28,1
4,3 6,3 90,3 52,9 45,0 36,4 32,6 22,6 22,6
4,3 6,3 80,3 47,0 40,0 32,3 29,0 20,1 20,1
4,3 6,3 72,3 42,3 36,0 29,1 26,1 18,1 18,1
4,3 6,3 56,2 32,9 28,0 22,6 20,3 14,1 14,1
TABLE VI.7
Fat i gue f i el d t est (Benal u)
81
EUROPEAN ALUMINIUM ASSOCIATION
The follow ing sections show s
good and bad design solutions
for alum inium trailer chassis.
They all refer to the load case
described in Figure VI.16.
8.2. Pr act i ce: compar i son bet w een good and bad chassi s sol ut i ons
®
®
®
®
®
®
®
®
®
®
®
®
7300
3000 2150
1000
1250
7
3
0
0
115
N
cm
BOUNDARY CONDITIONS AND BEAM GEOMETRY AS A BASIS
FOR THE FINITE ELEMENT ANALYSIS
FIGURE VI.16
®
®
®
®®®
®
®
®
®
®
®
®
®
®
1
6
5
1900 941
R1000
7300
6
0
100
4
0
0
R1000
1
Load case with 0,5x115 N/cm is used (dashed rectangle).
Cross section of the beam is a simple symmetrical H-section with a flange-width of 150 mm,
flange-thickness of 12 mm and web-thickness 8 mm.
(1: To achieve the gooseneck, a part of the web has been cut off and re-joined by welding
at a distance of 60 mm from the lower flange.)
82
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 82 | 83
8.2.1. Gooseneck
The G ooseneck area of the chas-
sis beam w ill be the m ost
stressed part and has to be very
carefully treated to avoid prob-
lem s. G enerally good precautions
w ill be:
•It is of utm ost im portance to
avoid all w elding or heat treat-
m ent on, or near, the flanges.
•N o w elded or bolted attach-
m ents to, or near, the flanges in
this area.
•N o joining of the beam s
and/or reinforcem ent of the
beam s in this area.
•N o sudden variation of m aterial
thickness or properties in this area.
It is obviously m andatory to fol-
low the fabrication or shop
draw ings, design m anuals, w eld-
ing procedures, Q A -m anuals and
the designer’s guidance through-
out the w hole fabrication
process.
Figures VI.17, VI.18 and 6.19 pres-
ent a few lifespan exam ples
depending on the geom etry of the
G ooseneck (i.e. curvature radius).
O ne can see the increase in stress
level is approxim ately 70% and
the increased deflection (δ)
approxim ately 23% .
The consequence w ill be a rela-
tive lifespan decrease of 50 %
PLAIN CHASSIS BEAM, R = 1000 mm (σ
max
= 43 MPa, δ = 5.3 mm)
FIGURE VI.17
PLAIN CHASSIS BEAM, R = 450 mm (σ
max
= 73 MPa, δ = 6.9 mm)
FIGURE VI.18
σ
max
= 43 M Pa
σ
max
= 73 M Pa
®
®
PLAIN CHASSIS BEAM, R = 300 mm (σ
max
= 85 MPa, δ= 7.5 mm)
FIGURE VI.19
σ
max
= 85 M Pa
®
83
EUROPEAN ALUMINIUM ASSOCIATION
from the norm al radius of 450
m m to 350 m m . A s illustrated,
an increased radius of 1000 m m
w ill offer very low stresses and
dem onstrates sim ply the im por-
tance of sm ooth transitions.
8.2.2. Perforation
The fixture of the supporting legs
to the chassis beam w ill norm ally
be located at the highest stressed
area of the chassis beam , i.e. in
the gooseneck area. H ence a per-
foration of the bottom flange by
boltholes m ust be avoided as
w ell as any w elding on or near
the flange.
Figures VI.20 and VI.21 show the
consequence of perforating the
flange com pared to the w eb in
this area.
The reduced relative lifespan w ill
be as m uch as >80% due to the
effect of stress concentration in
the perforated area of the flange.
For the situation w ith the perfo-
ration through the w eb, the lifes-
pan w ill not be reduced. Both
exam ples show the im portance
of a location aw ay from the m ost
stressed area of the beam . If a
perforation through the flange is
inevitable, the location should be
as close as possible to the edge
of the flange (as far from the
w eb as possible). N ote that
HOLE IN CHASSIS BEAM FLANGE, (ø = 20 mm): σ
max
= 102 MPa
FIGURE VI.20
σ
max
= 102 M Pa
®
σ = 73 M Pa
®
HOLE IN CHASSIS BEAM FLANGE, (ø = 20 mm): σ
max
= 73 MPa (on flange)
FIGURE VI.21
σ = 35 M Pa
®
σ
max
= 73 M Pa
®
84
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 84 | 85
required m inim um distance from
the edge should be according to
actual standards, norm ally 1,5ø –
2,0ø depending on direction of
load, etc. A lso note that local
bending capacity of flange m ust
be checked according to actual
location.
8.2.3 Welding
A fixture by w elding in the w eb
area of the beam is a m uch-used
alternative to bolting, and w ill be
fully acceptable as long as w eld-
ing is avoided in or near the
flange (i.e. in the m ost stressed
area of the beam ). Figures VI.22
and VI.23 illustrate the conse-
quence of w elding on the flange
and on the w eb.
The lifespan reduction w ill be as
m uch as >90% in the case of the
fixture by w elding on flange, due
to the effect of stress concentra-
tion in the w elded area of the
flange and the decreased m ateri-
al properties due to heating.
The fixture by w elding in the w eb
area w ill be of no effect to lifes-
pan. In both cases a geom etrical-
ly perfect w eld is assum ed. In real
life, im perfections are com m on
and therefore good w orkm an-
ship and after treatm ent of w elds
m ust be considered.
FIXTURE BY WELDING ON FLANGE: σ
max
= 97 MPa
FIGURE VI.22
σ
max
= 97 M Pa
®
σ = 73 M Pa
®
FIXTURE BY WELDING ON WEB: σ
max
= 73 MPa (on flange)
FIGURE VI.23
σ
max
= 73 M Pa
®
σ = 25 M Pa
®
85
EUROPEAN ALUMINIUM ASSOCIATION
9. Speci al desi gn i ssues
9.1. Tank s f or t he
t r anspor t of danger ous
goods - ADR
Tanks for the transport of dan-
gerous goods have to be built
according to the rules defined in
the follow ing agreem ent and
standards:
•ADR: Agreem ent for the trans-
port of Dangerous goods by Road
1
•EN 13094 “Tanks for the
transport of dangerous goods -
M etallic tanks w ith a w orking
pressure not exceeding 0.5 bar -
D esign and construction”
•EN 14025 “Tanks for the
transport of dangerous goods -
M etallic pressure tanks - D esign
and construction”
In particular, tank shell thickness
(e) is determ ined by the follow -
ing equivalence form ula, w here
e
0
is the m inim um shell thickness
for m ild steel and R
m
and A , the
tensile strength and elongation
of the m etal chosen.
e =
e
0
× 464
3

(R
m
× A )
2
Furtherm ore, absolute m inim um
shell thicknesses are fixed
depending on the type of tank,
the shell dim ension and the
m aterial used.
For tanks protected against dam age:
•For shells w ith circular cross-section ≤ 1.80 m :
e
0
= 3 m m
e cannot be low er than 4,00 m m for alum inium alloys
2
•For shells w ith circular cross-section > 1.80 m
e
0
= 4 m m
e cannot be low er than 5,00 m m for alum inium alloys
•For other tanks:
e
0
= 5 m m for shells w ith circular cross-section ≤ 1.80 m
e
0
= 6 m m for shells w ith circular cross-section > 1.80 m
1. See A D R - A nnex A –Part 6 –C hapter 6.8:
http://w w w .unece.org/trans/danger/danger.htm
2. W hatever the result of the equivalence form ula is.
Al umi ni um road t ankers (Schrader)
86
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 86 | 87
Suitable alum inium alloys for that
application are listed in standard
EN 14286 “A lum inium and alu-
m inium alloys - w eldable rolled
products for tanks for the stor-
age and transportation of dan-
gerous goods”. See also C hapter
V, section 6.4 in this m anual.
For tanks protected against dam -
age, several alloys listed in EN
14286 allow m anufacturing tank
shells w ith e = 5.3 m m (corre-
sponding to R
m
x A = 6600) and
even e = 5.0 m m (for those w ith
R
m
x A ≥ 7152).
9.2. Ti pper s
9.2.1. Construction
Tipper body trailers (or “dum p
bodies”) are constructed in tw o
different versions:
•C om bination of plates and
extrusions (m ore frequently used
version)
•Extrusion intensive construc-
tion, w here all sides of the trailer
are m ade of clam ped and / or
w elded extrusion profiles
A nother version w hich cam e up
in the last few years is a m aterial
–m ix version w ith a steel bottom
plate and alum inium side- w alls
(bolted to the steel plate).
Tw o m ain tipper types can be dif-
ferentiated:
•Rectangular trailer
•H alf –pipe trailer
Independent from the type of tip-
per, all extrusion cross –sections
and the thickness of the plates
are calculated w ith respect to:
Al umi ni um t i pper bodi es (St as)
87
EUROPEAN ALUMINIUM ASSOCIATION
W ear is not only taken into
account for the calculation of the
actual plate or extrusion thick-
ness, especially of the bottom
plate, but also for the type of alu-
m inium to be chosen.
9.2.2.1. Defintion of Wear
The m echanism of w ear is quite
com plex. W ear generally occurs
w hen one surface (usually harder
than the other) cuts off m aterial
from the second. The area of con-
tact betw een the tw o surfaces is
thereby very sm all and concen-
trated on surface asperities. The
shear forces are transferred
through these points and so the
local forces can be very high.
A brasives can act like in a grind-
ing process w here the abrasive is
fixed relative to one surface or in
a lapping process, w here the
abrasive tum bles, producing a
series of indentations.
•A ctual load (com pression /
tension)
•Bending forces (static and dur-
ing tipping operation)
•O ther forces like shear stress,
deflection, buckling
In addition, the type of products
to be transported has to be taken
into consideration during design
of the tipper. This is due to the
fact, that the load can be just
concentrated locally and on a
very sm all area or it can be divid-
ed quite uniform across the
w hole bottom of the tipper body.
9.2.2. Wear
W ear (or abrasion- resistance) is
the m ost discussed issue w hen it
com es to the construction of an
alum inium tipper. A lot of uncer-
tainties about the abrasion –
resistance of the alum inium as
w ell as the totally different type
of loads m akes it nearly im possi-
ble to find a perfect solution for
each transport problem .
9.2.2.2. Factors i nfl uenci ng
the wear
The w ear condition can vary
extrem ely from one load to
another. Therefore it is not
alw ays possible to link the actual
hardness of a w ork-hardened
alloy to the w ear resistance
3
. It
w as found out that for a very
large extent, the type of load is a
decisive factor.
Soft goods like potatoes, fruits,
sugar beets or other agricultural
products are m uch less abrasive
than m ineral goods. In case of
m ineral goods like stones, pow -
ders, cem ent, chalk etc. the size,
form (sharpness) and hardness of
the m aterial is by far the m ost
critical factor regarding abrasion
(in laboratory tests even the
change of a type of sand
increased the w ear by 35% ).
3. Abrasive wear of aluminium alloys
rubbed against sand, K. Elleuch,
S. M ezlini, N . G uerm azi, Ph. Kapsa,
W ear 261 (2006) 1316–1321
Product i on of al umi ni um t i pper bodi es (Schmi t z)
88
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I DESI GN A N D CA LCU LATI ON 88 | 89
Even the w ear debris acts there-
by as an additional source for
abrasion.
A lso the num ber of tipping opera-
tions is to be considered. The m ore
often the trailer is tilted, the m ore
often abrasion occurs. The num -
ber of cycles has a linear function
w hen set into relation to the m ass
lost of the alum inium plate.
Very often, tippers are used by
the transport com panies for
other products than they are
originally m ade for and so a reli-
able calculation of the lifetim e of
an alum inium bottom plate can-
not be determ ined.
9.2.3. Material selection
The choice of m aterial for the
bottom plate of tipping trailers is
now adays often a question of
specific experience, m aterial
availabilty and m anufacturer´s
specific production m ethods.
Typical bottom plate m aterial is:
•5083 H 32, H 321, H 34
•5086 H 24
•5383 H 34
•5454 H 22, H 24
•5456 H 34
or other, m ill-specific alloy types.
10. Ref erences
•EN 1999-1-1 Eurocode 9
Design of aluminium structures,
Part 1-1 General structural rules.
•EN 1999-1-3 Eurocode 9
Design of aluminium structures,
Part 1-3Structures susceptible to
fatigue.
•EN 1090-3 Execution of steel
structures and aluminium struc-
tures, Part 3 Technical require-
ments for aluminium structures
•EN-ISO 10042 Arc-welded joints
in aluminium and its weldable
alloys – Guidance on quality lev-
els for imperfections.
•BS 8118 Structural use of alu-
minium, Part 1 Code of practice
for design.
•A D R: A greem ent for the trans-
port of D angerous goods by
Road.
•EN 13094 Tanks for the trans-
port of dangerous goods -
Metallic tanks with a working
pressure not exceeding 0.5 bar -
Design and construction.
•EN 14025 Tanks for the trans-
port of dangerous goods -
Metallic pressure tanks - Design
and construction.
•EN 14286 Aluminium and alu-
minium alloys - weldable rolled
products for tanks for the stor-
age and transportation of dan-
gerous goods.
Ful l al umi ni um t i pper (Menci )
89
EUROPEAN ALUMINIUM ASSOCIATION
90
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
1. 1. 5000 series alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
1. 2. 6000 series alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92
1. 3. 7000 series alloys . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2. FABRICATION OF PRODUCTS FROM PLATE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2. 1. Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 93
2. 2. Marking out . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
2. 3. Cutting to shape . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94
2. 4. Edge rolling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
2. 5. Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
2. 6. Non-machinable faces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 97
3. FABRICATION OF PRODUCTS FROM EXTRUSIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
3. 1. Storage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
3. 2. Cutting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
3. 3. Bending . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 98
4. DRILLING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4. 1. Twist drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4. 2. Straight flute drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
4. 3. Gun drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102
4. 4. Half-round or three quarter round drill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 102
5. TAPPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5. 1. Chip removal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
5. 2. Upsetting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
5. 3. Threaded inserts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
6. DEEP DRAWING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
7. SPINNING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7. 1. Advantages of spinning . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
7. 2. Diameter of spinning blanks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
CHAPTER VI I
FABRI CATI ON
91
EUROPEAN ALUMINIUM ASSOCIATION
The form ing operations used in
the com m ercial vehicle industry
are m any and various. The m an-
ufacturer w ill cut, fold, roll and
bend sem i-finished sheets and
extrusions to produce a vehicle
or an accessory.
These operations, som e of w hich
such as cutting and drilling can
now be program m ed and auto-
m ated, are carried out according
to rules w hich w e have sum m a-
rized in this chapter. In certain
cases and in som e countries they
are also standardized, and the
relevant standards are referred to
w here they exist.
In any case, it is very im portant to
use equipm ents dedicated to alu-
m inium .
M ost alum inium alloys used in
com m ercial vehicles belong to
the fam ily of alum inium -m agne-
sium alloys (5000 series) for rolled
products or to the alum inium -sili-
con-m agnesium fam ily (6000
series) for extruded products.
1.1. 5000 ser i es al l oys
In soft conditions, 5000 series
alloys have excellent form ing
properties as suggested by the
difference betw een proof stress
and ultim ate tensile strength and
by the level of elongation
1
.
A s m etals are hardened by
m echanical cold w orking, it m ay
be necessary to im prove ductility
so as to continue form ing by
m achine or by hand. This is done
by annealing
2
, a process that is
easy to accom plish either in a
furnace or w ith a w elding torch,
using tallow as a tem perature
indicator w hich turns a light
brow n colour at 340 °C . H eat
indicator crayons or even a stick
pyrom eter m ay also be used.
If necessary, inter-stage anneal-
ing can be repeated betw een
shaping operations, how ever
there is one golden rule: only
anneal the m etal if it becom es
difficult to w ork, in other w ords
w hen the w ork-hardening rate
is greater than or at least equal
to the so-called critical w ork-
hardening rate.
1.2. 6000 ser i es al l oys
These are used m ainly as extruded
sections. The m ain alloy elem ents
are m agnesium and silicon.
These are heat treatable alloys
supplied in the T6 or T5 condi-
tion and, less com m only, in the
T4 or T1 condition
3
.
G enerally speaking the shaping
properties of this fam ily of alloys
in the fully heat-treated condi-
tion are lim ited. N evertheless
shaping should be perform ed
cold as heating w ill considerably
reduce m echanical properties
(approx. 40 % ).
M ore com plex shaping of the
extrusions m ay be done in the T1
or T4 condition, before ageing to
full hardness in T5 or T6. In this
case it is beneficial to do the
form ing w ithin a short tim e w in-
dow of a few days after the solu-
tion heat-treatm ent to T1 or T4,
1. Introducti on
1. Please refer to EN 485-2.
2. For 5000 alloys w ith M g content
above 3% , this m ust be done very care-
fully to prevent sensitization to inter-
granular corrosion. See also C hapter XI,
section 2.2.6.
3. Please refer to C hapter V section 5,
for an explanation of these tem pers.
92
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 92 | 93
i.e. before that the m aterial gets
hardened by cold-ageing.
If very extensive shaping is to be
done, it is possible to do this in a
tim e-span of a few m inutes after
the treatm ent to T1 or T4.
1.3. 7000 ser i es al l oys
These extrusions are used in
som e high-strength applications
w ithin transportation, autom o-
tive and sports equipm ent. The
m ain alloy elem ents are zinc and
m agnesium .
The extrusions are used in the T5,
T6 or a T7 over-aged condition.
The shaping m ay take place in
the T1 or T4 condition, before
the m aterial is artificially aged.
M ore com plex form ing is done in
the T4 condition, shortly after
the solution heat treatm ent,
before ageing to T6 or T7.
Before using 7000 alloys, prior
consultation w ith the supplier is
strongly recom m ended.
The general m ethods of alum inium
alloy fabrication and the m achines
used are not very different from
those used for steel. Alum inium
alloys are easy to fabricate.
H ow ever, their relative softness
m ust be taken into account and
it is essential to use special tools
to avoid dam aging alum inium
surfaces. Risks of contam ination
from traces of ferrous and
cuprous m etals m ust also be
avoided as these can cause local-
ized corrosion. It is essential to
w ork in an environm ent w here
such risks are m inim ized.
2.1. St or age
A lum inium sheets are classified
by fam ily of alloy and stored
upright w hen m ore than 0.8 m m
thick (Figure VII.1). Thin sheets
(less than 0.8 m m ) should be
stored flat.
A lum inium sheets should never
be placed directly on the ground,
even if concreted, and should be
kept aw ay from splash w ater,
condensation and hostile envi-
ronm ents.
They are best stored under cover
in a ventilated area and separat-
ed by tim ber blocks to prevent
condensation stains.
2. Fabri cati on
of products f rom pl ate
STO RA G E
FIGURE VII.1
93
EUROPEAN ALUMINIUM ASSOCIATION
2.2. M ar k i ng out
Scribing tools should not be
used, since any tracing m arks
w hich m ight be left on the fin-
ished com ponent can becom e
crack starters under high loads.
This precaution is not necessary
w here the scribe indicates a cut-
ting line.
A s a general rule it is advisable to
trace using a hard pencil (e.g.
5H ) w hich is easier to see and
easy to erase in case of error.
2.3. Cut t i ng t o shape
Plate or crocodile shears can be
used to m ake straight cuts. The
rating of the shear should be
m ore or less the sam e as for cut-
ting non-alloyed steel w ith low
carbon content and the sam e
thickness.
Saw ing is a com m on cutting
process w hich is very econom ical
for alum inium alloys.
2.3.1. Band saw
The m ost com m on type of saw is
the band saw . This can be a sim -
ple tim ber band saw but w ith a
blade of specially designed pro-
file to break and dislodge the
alum inium chips from betw een
the saw teeth.
This is achieved by the alterna-
tion or pitch of the teeth and by
the clearance angle defined
Figure VII.2.
2.3.2. Circular saw
As w ith the band saw , the saw
pitch varies w ith the thickness or
section to be saw n but the process
of cutting, w hich is a function of
the m achine characteristics, m akes
it sim ilar to m illing (Figure VII.3).
W ith the band saw and circular
saw , the cutting speeds for
3000, 5000 and 6000 series
alloys are as follow s:
•H SS blade: 600 m /m in to 1000
m /m in.
•C arbide blade: 800 m /m in to
1500 m /m in.
The portable m illing saw is a tool
that can be used to straight cut
products up to 20 m m thick and
w ith good rates of advance.
It m ay be preferable to use a jig-
saw for thicknesses of 6 m m or
less. The jigsaw is highly
m anoeuvrable and can be used
to cut com plex curves.
BA N D SAW
FIGURE VII.2
®
®
®
®
®
®
®
®
®
2,5 to 8 m m
1,8 t
55°
t
3° to 0°
THE CHARACTERISTICS O F A BAND SAW FO R ALUM INIUM ARE AS FO LLO W S:
•E (thickness) =
D iam eter of flyw heel
1000
•W idth = 10 to 30 m m
•Tooth pitch = 2.5 to 8 m m ; tw o teeth m ust alw ays be in action
•Lubricant = tallow or soluble oil.
SAW - M ILLIN G O R C IRC U LA R
FIGURE VII.3
®
®
® ®
®
®
®
®
25°
h
p
d
®®
® ®
®
® ®
®
®
®
®
®
t

3
t

3
t t
60° 60°
d: draw of 8°
over 1 m m of w idth
94
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 94 | 95
2.3.3. Fluid jet
M etals, including alum inium
alloys, can be cut using w ater
jets bearing abrasive particles
(PA SER process) at high pressures
(3000 bars and over). G ranules
of garnet, corundum or other
very hard m inerals are used.
The advantage of this process is
that it does not affect the m etal-
lurgical condition of the product
and is very versatile.
Its perform ance is also excellent,
and in alum inium , thicknesses
betw een 1 and 100 m m can be
cut at rates of 3500 m m /m in
dow n to 30 m m /m in for the larg-
er thickness.
Wat er j et cut t i ng (SAG)
95
EUROPEAN ALUMINIUM ASSOCIATION
2.3.4. Plasma
There are tw o plasm a cutting
techniques (Figure VII.4):
•traditional plasm a, w ith a draft
of som e 6°,
•w ater VO RTEX plasm a, w ith
a very sm all cutting draft, of the
order of 2°.
C om pared to traditional plasm a,
w ater VO RTEX plasm as facilitate
greatly increased cutting speeds
and reduce nuisance factors such
as sm oke, noise, ozone discharge.
The process requires substantial
am ounts of pow er how ever.
The plasm a is form ed in a special
torch, and an inert gas (usually
argon or nitrogen) m oving at
great speed is dissociated under
the effect of an electric arc to
attain the plasm a state.
O w ing to its high cutting speed
(several m etres per m inute), its
quality and precision of cut and
suitability for autom ation, a plas-
m a cutting m achine can be a
highly profitable investm ent,
even for short production runs.
2.3.5. Laser cutting
This process is m ainly used in the
autom otive industry.
M ore inform ation can be found
in the A lum inium A utom otive
M anual (w w w .eaa.net/aam ).
Note:
The width of the heat affected
zone is less than 1 mm whatever
the alloy and for all thicknesses.
However cracking is sometimes
observed in the short transverse
dimension (Figure VII.5) that can
attain a depth of some 2 mm.
Whatever the thickness of the
product, machining off 2 mm of
material will restore the metal's
original qualities.
This is obviously unnecessary if
the cut pieces are intended for
use as welding blanks.
PLA SM A TEC H N IQ U ES
FIGURE VII.4
®
®
+
+
-
®
®
C ooling
w ater
®
Electrode
®
Plasm agen gas
Plasm agen gas
Electrode
®
® W ater cone
Plasm a colum n
Vortex w ater inlet
®
Plasm a in vortex Plasm a in free air
-
FIBRE O RIEN TATIO N
FIGURE VII.5
®
®
®
®
®
®
D
ire
c
t
io
n
o
f
ro
llin
g
Transverse
direction
L
o
n
g
it
u
d
in
a
l
d
ir
e
c
t
io
n
s
h
o
r
t

t
r
a
n
s
v
e
r
s
e
d
i
r
e
c
t
i
o
n
®
C opper
®
96
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 96 | 97
2.4. Edge r ol l i ng
This shaping technique requires
no special equipm ent for alu-
m inium . The rollers m ust of
course be clean and have
sm ooth surfaces.
2.5. Bendi ng
For m ultiple folds, holes should
be used to m ark the crossover
points of the fold lines to avoid
causing cracks w hen the folds
are m ade.
A lum inium does not require any
special bending tools, and con-
ventional table bending
m achines or presses are perfectly
adequate provided the w orking
parts of the tooling are free from
unacceptable irregularities.
The bending radii to be observed
as a function of the thickness are
given in standard EN 485-2.
2.6. Non-machi nabl e f aces
A s w ith bending, one w orth-
w hile precaution is to rem ove all
score m arks from the edges
caused by cutting so as to pre-
vent the form ation of cracks at
points of deep deform ation.
Shaping is carried out on the
5754, 5086 and 5083 grades
(and on other alloys in the sam e
fam ily) in the annealed or H 111
condition. In som e cases shaping
m ay call for inter-stage anneal-
ing
1
, and this can be done as
described before using an
annealing torch and tallow as
tem perature indicator.
Inter-stage annealing can be
carried out several tim es in the
course of the shaping opera-
tion; how ever care should be
taken to avoid annealing a
m etal that is only slightly w ork-
hardened to prevent the risk of
grain enlargem ent.
Pl asma cut t i ng (Benal u)
1. For 5000 alloys w ith M g content
above 3% , this m ust be done very care-
fully to prevent sensitization to inter-
granular corrosion. See also C hapter XI,
section 2.2.6.
97
EUROPEAN ALUMINIUM ASSOCIATION
Extrusions are usually individually
protected in packing cases to
prevent problem s such as fret-
ting in transit.
3.1. St or age
Extrusions are best left in their
original packing cases until
required. A s w ith alum inium
sheets, they should never be set
dow n directly on the ground,
even if concreted, and should be
kept aw ay from splash w ater,
condensation and hostile envi-
ronm ents to prevent possible
corrosion during storage.
3.2. Cut t i ng
The processes of saw ing
described above are also suitable
for cutting alum inium extrusions
.
3.3. Bendi ng
The bending of extrusions on an
industrial scale m ay be carried
out w ith different m ethods and
m eans.
3. Fabri cati on of products f rom extrusi ons
3-poi nt press bendi ng (Benal u)
98
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 98 | 99
3.3.1. Bending by 3-point
press-bending
This m ay be done w hen the bend
radius is sm all com pared to the
height of the extrusion section,
and w hen the accuracy (spring-
back) of the bend as w ell as the
optics are not so im portant. It is
typically perform ed in a sim ple
tool in a (m ostly) hydraulic press.
3.3.2. Bending by 3-point
press-bending with rotating
dies
This process is typically using a
tool in a press or a bending
m achine. The rollers m ay be
kinder to the extrusion w ork piece
than by the m ethod in 3.2.1 due
to less abrasive sliding action
betw een tools and w ork piece.
3.3.3. Bending by
compression bending
A sliding tool forces the extrusion
to follow a circular die. The
extrusion is not m oving length-
w ise relative to the die.
99
EUROPEAN ALUMINIUM ASSOCIATION
3.3.4. Bending by
compression roll-forming
It is identical w ith 3.3.3, but w ith
a rotating w heel instead of the
sliding tool. Very severe reform ing
m ay be m ade. It is usually per-
form ed in roll-form ing m achines
w ith purpose-built tools.
3.3.5. Bending by rotary
draw bending
It is m ostly perform ed in stan-
dard tube-bending m achines.
3.3.6. Stretch-bending over a
fixed tool (“swing arm
stretch-bending”)
The ends of the profile are gripped
to stretch-bend the profile against
a fixed last w hich has the form of
the finished product. In m any
cases this form m ay be a bending
sw eep built-up by com pounded
radii. N early all of the cross section
of the extrusion w ill be subjected
to tensile stress above the yield
stress lim it, and this applies to the
full length of the w ork piece. This
m eans that the spring-back effect
on global shape w ill be little, con-
stant and predictable. W hen a
closed extrusion is form ed in this
w ay, the outer w all m ay be sub-
jected to sagging. This m ay be
countered by using a basic extru-
sion w ith an outer w all w hich is
barrel-shaped outw ard or by
inserting a suitable elastic m aterial
(e.g. rubber). The operation m ay
be perform ed by a dedicated tool
in a press or in a stretch-bending
m achine.
Bendi ng over rot at i ng t ool s
100
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 100 | 101
3.3.7. Stretch bending
by rotating dies (rotary
stretch bending)
By this m ethod the extrusion is
gripped at its ends and bent over
one ore tw o (norm ally tw o)
rotating dies having a contour
corresponding to the final prod-
uct shape. The stretching com es
as a result of the rotation and
m ay effectively be controlled by
the location of the rotary axes.
A s opposed to the situation in
conventional stretch bending
m ethod (3.3.6), the bending
starts at the end and propagates
tow ards the centre of the extru-
sion. The prim ary bending
m om ent is generated by the
rotating dies, and is typically con-
stant along the w orkpiece. The
process is characterized by very
low transversal (shear) forces and
thus also low contact forces
betw een extrusion and dies.
Rotary stretch bending can be
im plem ented in a dedicated
press tool or in a stand-alone
bending m achine.
3.3.8. Three-dimensional
stretch-bending
O ver fixed or rotating dies (lasts),
the extrusion si gripped at its
ends, and stretched into a three-
dim ensional shape (“out of the
plane”). This m ay be done w ith
tools w here the m ovem ents are
defined m echanically, or in pro-
gram m able tools or m achines.
3.3.9. Manipulation
of the cross section
This is usually perform ed by
indenting or pressing in a dedi-
cated tool in a press.
3.3.10. Mechanical calibration
of parts of the extrusion
This is usually perform ed by com -
pression-stretching or expansion-
stretching in a dedicated tool in a
press.
3.3.11. Achievable bending
radius
The achievable radii for bent
extrusions are highly dependent
on the geom etry of the profiles
and are difficult to predict.
Therefore it is advisable to carry
out tests on specim en. Table VII.1
gives guidance for bending of
hollow circular tubes. If sm aller
radii are needed, filling of the
tubes w ith sand before bending
is helpful.
D: Outside diameter t: Thickness
BENDING HOLLOW TUBES (D ≤ 90mm) BENDING RADIUS AS A FUNCTION OF RATIO D/t
Alloy Temper
Ratio D/t
5 10 15 20 25 30
5754 H 111 1 to 1.5 D 2.5 to 3 D 3.5 to 4 D 4.5 to 5 D 6 to 7 D 8 to 9 D
6060 O 1 to 1.5 D 2.5 to 3 D 3.5 to 4 D 4.5 to 5 D 5 to 6 D 7 to 9 D
T5 2 to 2.5 D 3 to 4 D 4 to 5 D 6 to 7 D 8 to 10 D 12 to 15 D
TABLE VII.1
101
EUROPEAN ALUMINIUM ASSOCIATION
D rilling alum inium alloys is a sim -
ple operation but calls for careful
sharpening and polishing of the
drills given the relative softness
of the alum inium alloys used in
the m anufacture of com m ercial
vehicles. If inadequate sharpen-
ing causes the drill to bend or
buckle, it w ill tear the m etal
around the part of the hole that
is already drilled.
The follow ing types of drill can be
used for drilling alum inium alloys
3
:
•the standard tw ist drill - the
m ost com m on type,
•the straight flute drill,
•the gun drill,
•the half-round or three quarter
round drill.
4.1. Tw i st dr i l l
To have a substantial sharpening
gradient, the helix angle m ust be
40° w hile the point angle varies
from 120° to 140° according to
the shape of the neck, w ith a
clearance angle of 8°. The other
characteristics of the tw ist drill
are as follow s:
•cutting speed 30 to 80 m /m in
depending on rating and the
desired quality - for very accurate
holes the ideal speed is 30 m /m in,
•penetration rate determ ined by
the drill diam eter: 0.05 m m /rev
for a 2 m m diam eter drill, to 0.3
m m /rev for a 30 m m diam eter
drill,
•soluble oil cooling,
•point height : this m ust
exceed the thickness of the
drilled m aterial.
4.2. St r ai ght f l ut e dr i l l
This drill facilitates rapid chip
rem oval and is m ore efficient for
alum inium alloys of m edium
hardness than the tw ist drill. The
four cylindrical w itnesses also
prevent "triangulation" of the
hole and provide drill guidance.
4.3. Gun dr i l l
This type of drill is excellent for
large diam eter holes of 20 m m
and over, also for drilling stacked
sheets. The drilling conditions are
the sam e as for the standard
tw ist drill.
4.4. Hal f - r ound or t hr ee
quar t er r ound dr i l l
These drills are used m ainly in
boring operations. The accuracy
of the bore diam eter achieved
w ith these tools is of the order of
0.02 m m :
•cutting speeds are betw een 10
and 15 m /m in,
•rate of advance is 0.05 m m /rev,
•cooling is w ith cutting oil.
4. Dri l l i ng
3. Steel tw ist drills can be used for sm all
runs w ith m ainly m anual tools.
102
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 102 | 103
Threads in alum inium m ay be
m ade, w hen other joining tech-
niques are not applicable
4
.
If threads are m ade in alum ini-
um , care should be taken to
ensure that the thread length is
sufficient for the purpose. The
thread length m ay be betw een 1
and 2 tim es the m ajor diam eter
of the threads, and m ust depend
on the application, the alloy as
w ell as the tem per of the m ateri-
al. For exam ple, the necessary
thread length of a high strength
6000 alloy in T6 m ay be 1.2 tim es
the m ajor thread diam eter.
C onversely a softer alloy dem ands
a longer thread length.
There are tw o m ethods of tapping:
•by chip rem oval,
•by upsetting.
5. Tappi ng
DIAMETER OF PILOT HOLES FOR THREAD TAPPING
∅ nominal 4 5 6 8 10 12 14 16 18 20
Pitch 0.70 0.80 1 1.25 1.50 1.75 2 2 2.5 2.5
D iam eter 3.2 4.2 4.9 6.6 8.3 10 11.7 13.7 15 17
TABLE VII.2
4. In a connection, w here continuous
joining m ethods such as w elding or
bonding are used, no additional fasten-
ers should be applied.
Threaded holes in alum inium should
only be used w here no other possibility
exists and the yield strength of the m etal
exceeds 200 N /m m 2. The bearing length
of the bolt should be 1,5 x diam eter of
the bolt. If the bolts m ust be used for
repeated loosening and tightening,
inserts should be applied e.g. H elicoils.
5.1. Chi p r emoval
O nly taps w ith straight threads
should be used to avoid seizing
the m etal at the flanks. Table
VII.2 gives diam eters for pilot
holes for tapping alum inium
alloys in the 5000 and 6000
series. Pilot holes for these alloys
in the annealed condition m ust
be som e 3-5% bigger than in
Table VII.3 and for castings w ith
12 and m ore % silicon content
som e 2% sm aller.
The cutting speed varies from 10
to 50 m /m in depending on the
m achine and m ethod of clam p-
ing the tap, w hether floating or
in a chuck. C ooling is done w ith
cutting oil.
103
EUROPEAN ALUMINIUM ASSOCIATION
5.2. Upset t i ng
The thread is achieved by plastic
deform ation of the m etal using a
tap w ith- a rounded polygon sec-
tion that has no cutting w edge.
The diam eter of the pilot hole
w ill depend on the desired
thread depth, and m ust be
drilled accurately. U psetting
speeds can attain 50 m /m in,
cooling is done w ith cutting oil.
Tapping by upsetting offers a
num ber of advantages w ith alu-
m inium alloys:
•the tap has a long life,
•it increases the hardness of the
thread, its tearing resistance and
fatigue strength,
•no chips.
5.3. Thr eaded i nser t s
It is usual to use threaded inserts
–available in diam eters M 2 to
M 68 (Figure VII.9) – w hen
screw ed alum inium alloy assem -
blies are required to be frequent-
ly dism antled. The inserts are in
the form of a spring m ade from
rolled w ire or are a diam ond sec-
tion m ade of stainless steel.
C aptive threads can also be used.
These have one or tw o flights
that grip the flanks of the screw
thread and counteract the loos-
ening effects of dynam ic stress-
es, vibrations or therm al shock.
Boring is done using a standard
tw ist drill, but tapping m ust be
done w ith a special tap. A ll chips
and cutting fluid m ust be
rem oved from the bore before
the insert is fitted.
Threaded inserts are fitted w ith
pneum atic hand tools w hich
hold them by a driver at the top
end of the thread. This can then
be broken off after fitting.
Threaded inserts can also be
used to repair a tap in alum inium
that is w orn or has been rejected
during m anufacture.
D eep draw ing is m ainly used in
the autom otive sector.
For m ore inform ation on that
technique, please refer to the
A lum inium A utom otive M anual:
http://w w w .eaa.net/aam /
H ELI-C O IL IN SERTED TH REA D
FIGURE VII.9
®
®
N otch
D river
6. Deep drawi ng
104
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I FA BRI CATI ON 104 | 105
Spinning is a form ing technique
used in the com m ercial vehicle
industry to m ake som e com po-
nents such as tank-ends.
7.1. Advant ages of
spi nni ng
The tools used in spinning are
very sim ple, being basically the
internal shape of the required
form . H ow ever production tim es
can be up to 20 longer than for
deep draw ing.
C alculations com bining the cost
of tooling and production costs
show that spinning is com petitive
for short runs.
7. Spi nni ng
D IA M ETER O F SPIN N IN G BLA N KS
FIGURE VII.10
®
®
®
®
®
®
®
®
®
®
D D d
H
h
∅ blank =
D × Π
2
∅ blank = h + D
4
3
∅ blank = H + d
7.2. Di amet er of spi nni ng
bl ank s
Three form ulae are used to
quickly determ ine the diam eter
of blanks for the m ost com m on
shapes (Figure VII.10). In spin-
ning, the diam eter of the blank is
less critical for the success of a
part than it is in deep draw ing,
and it is only the cost of the
m aterial that dictates shape opti-
m ization. A sim plified calculation
is adequate for prototypes.
Spi nni ng
of an al umi ni um t ank-end
(Köni g)
105
EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION
106
CHAPTER VI I I
WELDI NG
1. FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 108
2. TIG WELDING (TUNGSTEN INERT GAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
2. 1. Manual TIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
2. 2. Automatic TIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
2. 3. TIG welding with AC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
2. 4. TIG welding with DC, reverse polarity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
2. 5. Edge preparation for TIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
2. 6. Choice of filler wire or rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
2. 7. Selection of welding process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
3. MIG WELDING (METAL INERT GAS) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
3. 1. Manual MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112
3. 2. Automatic MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
3. 3. Smooth current MIG Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 113
3. 4. Pulsed current MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
3. 5. Wire pulsation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
3. 6. CMT – Cold Metal Transfer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
3. 7. Edge preparation for MIG welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
3. 8. Choice of filler wire or rod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 117
3. 9. Selection of welding process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
4. PLASMA MIG WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
5. LASER WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 118
6. LASER MIG WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119
7. RESISTANCE WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
8. FSW - FRICTION STIR WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120
9. SURFACE PREPARATION BEFORE WELDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
10. QUALITY CONTROL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10. 1. Approval procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10. 2. Inspecting welded joints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123
10. 3. Weld defects & approval criteria . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124
11. DESIGN AND PREVENTION OF DEFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
11. 1. Causes of deformation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
11. 2. Solutions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126
107
EUROPEAN ALUMINIUM ASSOCIATION
1. Foreword
W elding is the m ost com m on
m ethod of joining used in the
m anufacture of com m ercial vehi-
cles and their bodies e.g. tanks,
tippers, dum pers, chassis etc.
The different physical, chem ical
and m echanical properties of
alum inium com pared w ith those
of steel lead to the specific
behaviour of alum inium during
w elding. In an atm osphere con-
taining oxygen, a w ell anchored
oxide layer builds up on alum ini-
um . This layer has a m elting point
of som e 2000°C against the
m elting interval of 630-660°C for
the m etal underneath. For quality
w elds this layer m ust be rem oved
or at least broken up.
D espite the fact that the m elting
interval of alum inium is by far
low er than that of steel, the high
therm al conductivity and the
high m elting energy m ake that,
for arc w elding, alum inium
requires about the sam e am ount
of energy as steel.
The therm al elongation of alu-
m inium is tw ice that of steel and
the loss in volum e of the w eld
pool during solidification is
im portant, causing distortion of
the joint, if no rem edial m easures
are taken. O ne m ethod of m ini-
m izing distortion is to select a
process w ith sm all energy input.
TIG and M IG arc w elding are the
tw o processes m ost com m only
used in the com m ercial vehicle
industry. The technical progress
m ade by other techniques such
as plasm a, laser, resistance or
friction stir w elding and the ever
grow ing diversity of sem i-fin-
ished products w ill encourage
the application of such w elding
m ethods w hich have up to now
been little used in the com m er-
cial vehicle industry.
Wel der (STAS)
108
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 108 | 109
In this process, an electric arc is
struck betw een a refractory elec-
trode m ade of tungsten and the
w orkpiece, w hile a shroud of
inert gas, usually argon, shields
the electrode and protects the
m olten pool against oxidation.
This process uses a high-frequen-
cy stabilized A C pow er source.
The oxide film is rem oved during
the negative phase, w hile the
positive phase ensures penetra-
tion and cooling of the electrode.
TIG w elding is suitable for m etal
thicknesses betw een 1 and 6 m m .
There is a TIG version w here heli-
um is used as the shielding gas.
This helps achieving a high tem -
perature in the arc but requires
direct current w ith straight polarity.
The effect of oxide film rem oval
is w eaker but the w elding pow er
is higher and products 10 to 12
m m thick can be w elded w ith a
single pass. H ow ever this process
is strictly for autom atic w elding
only ow ing to the difficulty of
keeping the arc at a constant
controlled height w ithin 0.5 m m .
2. TIG wel di ng (Tungsten Inert Gas)
PRIN C IPLE O F TIG W ELD IN G
FIGURE VIII.1
®
C ontact (for current)
Filler
M etal
A rc
®
®
®
®
®
Shielding G as
Shielding G as N ozzle
Tungsten Electrode
W elding Pow er
Source
W eld Seam
®
W ork Piece
®
109
EUROPEAN ALUMINIUM ASSOCIATION
2.1. M anual TI G w el di ng
For m anual TIG w elding, the filler
m aterial is a hand-held rod fed
into the w eld pool. The m anual
process is used m ainly for sm all
w elds, circular w elds and rela-
tively thin com ponents.
M A N U A L A N D M EC H A N ISED TIG W ELD IN G
FIGURE VIII. 2
M anual TIG W elding
Fully M echanised TIG
W elding
2.2. Aut omat i c TI G
w el di ng
H ere, the w elding torch is auto-
m atically guided and, if filler is
used, it is fed autom atically from
a reel.
A utom atic TIG w elding is an
attractive proposition for w elding
large production runs, especially
w hen there is no access to the
back of the w eld.
The fabrication of com pressed air
reservoirs is a good exam ple of
the use of autom atic TIG w eld-
ing. These reservoirs consist of a
sheet rolled and w elded to form
the straight cylindrical centre sec-
tion to w hich tw o deep-draw n
ends are w elded. If the ends are
butt joined to the centre w ithout
any backing to prevent the prob-
lem s associated w ith m oisture
retention, autom atic TIG w elding
can be used to m ake an easy
connection. It is also possible to
support the w eld pool by supply-
ing the argon from inside the
reservoir.
TIG w el di ng of an ai r pressure vessel (SAG)
110
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 110 | 111
2.3. TI G w el di ng w i t h AC
It is especially w ell suited for butt
and corner w elds on pieces in
the thickness range 1-6 m m . Full
penetration w elds can be m ade
w ithout backing bar. Tack w elds
m ust not be rem oved before exe-
cuting the seam w eld. C hanges
in w eld direction are easy to fol-
low w ith the torch and do not
require any dressing. The process
can also be used to sm ooth the
surface of a M IG w eld.
The w elding speed is low er than
for M IG w eld and, for w ork
pieces thicker than 6 m m , pre-
heating is required. The slow
w elding speed is also responsible
for a w ider heat affected zone
and greater distortion of the
assem blies.
For fillet w elds extrem e care is
needed to achieve full penetra-
tion w ithout lack of fusion at the
root.
In the tank and silo production,
double side TIG w elding of butt
w elds in vertical upw ards posi-
tion leads to excellent quality,
provided the tw o operators con-
trol the process w ell.
2.4. TI G w el di ng w i t h
DC, r ever se pol ar i t y
In this process the arc length is
below 1 m m , ideally 0.5 m m ,
w hich m eans that it is m ainly
used for m achine w elding. For
m anual operation only short
lengths can be executed in prac-
tice. O ne such application is
stitch w elding of assem blies
before the seam w elding. The
sm all cross section of these
stitches is such that they are
com pletely m olten up w hile lay-
ing the first pass of M IG w eld
over it and don’t need to be
reduced in cross section by
m echanical m eans.
The oxide film rem oval is w eaker
w ith this process so it is neces-
sary to reduce the oxide layer by
m echanical m eans before w eld-
ing.
2.5. Edge pr epar at i on f or
TI G w el di ng
In EN ISO 9692-3 this inform ation
is given com prehensively, so that
w e just indicate a few exam ples
for typical joints in vehicle m anu-
facturing (Table VIII.1, p. 115).
To avoid sharp notches, especial-
ly at the root of the w eld, all
edges m ust be carefully de-
burred before w elding. Instead
of grinding discs, m illing tools
should be used, because residues
of the disc on the surface can
cause porosity in the w eld.
2.6. Choi ce of f i l l er w i r e
or r od
See section 3.8
2.7. Sel ect i on of Wel di ng
pr ocess
See section 3.9
111
EUROPEAN ALUMINIUM ASSOCIATION
W ith M IG w elding the alum ini-
um alloy w ire is both the elec-
trode and the filler m aterial. It
uncoils autom atically from a reel
to the w elding tool (gun or torch)
as it is used up. The w elding
energy is supplied by a D C pow er
source (sm oothed current).
C onnection is m ade w ith reverse
polarity (i.e. m inus to the w ork-
piece) to ensure rem oval of the
oxide film and the fusion of the
w ire electrode at the sam e tim e.
Several M IG processes do exist...
PRIN C IPLE O F M IG W ELD IN G
FIGURE VIII.4
W ire Transport Rolls
®
W elding
Pow er
Source
®
W orkpiece
®
A rc
®
®
®
®
W ire Electrode
C ontact N ozzle
(for C urrent)
Shielding G as
N ozzle
®
W eld Seam
3.1. M anual M I G w el di ng
In its m anual version, M IG is cer-
tainly the m ost com m on w eld-
ing process used in the com m er-
cial vehicle industry, producing
high quality w elds at an attrac-
tive quality/cost ratio.
A s the filler w ire, that is the con-
sum able electrode, is alw ays
autom atically fed from a reel, the
m anual M IG w elding is also
know n as "sem i-autom atic M IG
w elding".
M anual M IG w elding is used for
all w elds of a com plex nature
w here the dim ensions and thick-
ness of the products are com pat-
ible w ith the M IG process and
w hen autom ation is not consid-
ered to be profitable.
If w e consider the exam ple of a
tank consisting in sheets rolled
and w elded to form cylindrical
sections, w e can see that the lon-
gitudinal w eld can be m ade by
autom atic M IG w hile the circular
w elds w hich join the sections to
one another are usually m ade
m anually on a turntable in tw o
opposing passes. The choice
betw een m anual or autom atic
M IG w ill depend largely on
accessibility.
3. MIG wel di ng (Metal Inert Gas)
112
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 112 | 113
3.2. Aut omat i c M I G
w el di ng
H ere, the w elding torch is auto-
m atically guided.
This is norm ally used for very
long straight w elds w here an
autom atic system is profitable. A
good exam ple is fabrication of
chassis side m em bers consisting
of tw o “T”sections w elded to
either edge of a central plate
w hich form s the w eb of the
built-up beam . The tw o w elds
w ould norm ally be m ade auto-
m atically and at the sam e tim e to
avoid problem s of deform ation.
A utom atic w elding is also pre-
ferred w here an attractive
appearance is desirable, e.g. for
stiffening channel w elded to the
side panels of vehicle bodies.
H ere the appearance and size of
the w eld bead can be repeated
to achieve the im pression of con-
sistency.
Finally, autom atic w elding - both
TIG and M IG - provides a repeat-
able w elding quality provided of
course that the w elding param e-
ters are fully defined to begin
w ith.
3.3. Smoot h cur r ent M I G
Wel di ng
This fast and econom ical process
allow s depositing a great quanti-
ty of filler m etal per unit of tim e.
The energy input is such that
butt w elds can only be produced
w ith the use of a backing bar,
either integrated into the shape
of the extrusion or as tem porary
rem ovable feature in stainless
steel, copper or even alum inium .
D ue to the relatively high w eld-
ing speed, the heat affected
zone
1
is narrow er than w ith TIG
w elding and thus the distortion
of the assem blies is less.
Thin gauge m aterial below 3 m m
is difficult to w eld w ith this
process because of the high
energy of the arc. If no other
equipm ent is available, then a
thin gauge filler w ire m ay be
used w ith reduced energy input,
but then the w ire feed can cause
instability of the process even if a
push-pull equipm ent is used.
If the preassem bly of structures is
carried out w ith stitches in the
M IG process, these short runs
m ust have a sim ilar cross section
as the first w eld pass and be
som e 100 m m long to be sound.
Before production w elding, these
stitches m ust be reduced in cross
section by m echanical m eans (no
disc grinders), so that they can
be m olten up w ith the w eld pass
and do not leave im perfections
near the root.
1. The extent of the heat affected zone
and the strength in the heat affected
zone are given in EN 1999-1-1.
Wel di ng of si de panel s
f or t i ppers (Menci )
113
EUROPEAN ALUMINIUM ASSOCIATION
3.4. Pul sed cur r ent M I G
w el di ng
A n im provem ent of the M IG
process has been achieved by
superim posing a pulsed current
over the m ain current, the object
being to m aintain a low average
current level w ithout sacrificing
arc stability.
The filler m etal is transferred to
the w eld pool every tim e the cur-
rent is high (i.e. one drop of m etal
per pulse). The "cold tim es"
w hen the current is low ensure
that arc stability is m aintained.
There are three operating m odes:
•synergetic mode: only the
rate of uncoiling has to be regu-
lated. The voltage and frequency
are regulated by electronic logic
circuits;
•manual mode: all the w eld-
ing param eters are adjustable;
•programme mode: each
param eter can be stored for
use according to production
requirem ents.
The pulsed M IG process is lim ited
to thin products of 2 < t ≤ 5 m m
and to vertical fillet w elds.
This process m akes it possible to
w eld thin gauge m aterial w ith
standard filler w ire. A s the w eld
pool can be better controlled,
butt w elds up to 5 m m thickness
can be executed w ithout backing
bar. Furtherm ore it is very helpful
for w elding in the vertical and
the over head position. The opti-
m al m achine setting is m ore
dem anding than for standard
M IG because there are m uch
m ore param eters to be defined.
The w idth of the heat affected
zone is analogue to the one for
standard M IG as is also the
am ount of distortion of the w ork
pieces.
For w elding over stitches see
rem ark under 3.3 above.
3.5. Wi r e pul sat i on
For gauges betw een 1 and 3 m m ,
a com plem entary option “the
w ire pulsation”could be added to
the previously described “current
pulsation”in order to im prove the
arc stability. This “w ire pulsation”
induces a double pulsation to cur-
rent signal and consequently to
the heat input. For T-joint of dis-
sim ilar gauges, the heat input dis-
tribution is difficult to m aintain
constant w ith classical pulsed cur-
rent. This double pulsation of cur-
rent insures the concentration of
heat input at the exact location of
the joint.
3.6. CM T – Col d M et al
Tr ansf er
For M IG w elding gauges low er
than 1 m m , the C M T process
(C old M etal Transfer) could be
used. W hen detecting a short-
circuit, this process retracts the
w ire so as to help detach the
droplet. The therm al input is
im m ediatly reduced and the
short-circuit current is kept sm all.
Wel di ng
of a t ruck door
114
Process Welding Weld Thickness Preparation Remarks
position bead
TIG A ll positions O ne side only 0.8 < t <1.5 A slight peak form ed by
the edges lim its
deform ation
TIG H orizontal O ne side only 0.8 < t < 5 C ham fered card, stainless
steel support, clam ped w eld
TIG A ll positions O ne side only 1.5 < t < 5 Tack-w elded free edges
back-w eld
possible
Tack-w elded free edges.
TIG A ll positions O ne side only 4 < t < 6 A ngle sam e principle but
w ith offset bevel
M IG A ll positions O ne side only 2.5 < t < 6 Back-w eld necessary after
w ith back-w eld gouging to base of
first pass
M IG A ll positions O ne side only 2.5 < t < 6 Stainless steel support
M IG A ll positions O ne side only 2.5 < t < 6
M IG H orizontal O ne side only 6 < t < 25 Back-w eld necessary after
and overhead* w ith back-w eld gouging to base of first
pass.
C learance: 1.5 m m m ax.
M IG H orizontal O ne side only 4 < t < 25 Ribbed stainless
and vertical* steel support
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 114 | 115
3.7. Edge pr epar at i on f or
M I G w el di ng
Just the m ost frequent exam ples
are given in the Table VIII.1
For m ore details please consult
EN ISO 9692-3.
* X-shaped bevels are preferred for com ponents 6 m m > t > 25 m m to restrict deform ation due to w elding.
TABLE VIII.1
ED G E PREPA RATIO N
80°
2 m m 1 m m
1 m m
1 m m
1 m m
2 m m
e
e
80°
80°
115
EUROPEAN ALUMINIUM ASSOCIATION
C H O IC E O F FILLER M ETA LS A S A FU N C TIO N O F TH E A LLO Y C O M BIN ATIO N
TABLE VIII.2
(a) 5000 series alloys w ith m ore than 3.5% M g are sensitive to intergranular corrosion w hen exposed to tem peratures over 65°C
and w hen used in certain aggressive environm ents (see section 2.2.6 in C hapter XI).
(b) 5000 series alloys w ith less than 3% M g and 3000 series alloys that contain m agnesium m ay be sensitive to hot cracking.
(c) The m echanical perform ance of the w eld depends on the internal soundness of the castings. G assed m aterials and injection
m ouldings are considered to be non-w eldable.
(d) The percentage of silicon in the filler w ire m ust be as near as possible to that in the casting.
(e) The w elding of alum inium -silicon castings (40000 series) to 5000 series alloys should be avoided w here possible as M g2Si inter-
m etallics form in the w eldm ent and w eaken the joint.
Each com bination has three possible choices - indicated w here the lines intersect - depending on the selected criterion:
O ptim um m echanical properties: top line –O ptim um resistance to corrosion: m iddle line –O ptim um w eld-
ability: bottom line
The filler m etal indicated is: 4 : series 4xxx ¡ 4043A , 4045, 4047A – 5 : series 5xxx ¡ 5356, 5183, 5556A
Alloy A
W rought 5
5000 Series 5 (a)
M g < 3% 4 - 5 (b)
W rought 5 5
5000 Series 5 5
M g > 3% (a) 5 5
W rought 5 - 4 5 - 4 5 - 4
6000 Series 5 5 5
4 4 4
W rought 5 - 4 5 - 4 5 - 4 5 - 4
7000 Series 5 5 5
w ithout copper 4 4 4
C ast 4 (e) 5 - 4 (e) 4 4 4 (d)
Si > 7% 4 5 4 4
(c) 4 4 4
4
W rought W rought W rought W rought C ast
Alloy B 5000 Series 5000 Series 6000 Series 7000 Series Si > 7%
M g < 3% M g > 3% w ithout copper
(c)
116
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 116 | 117
M ost of the alloys listed in
C hapter V are w eldable and also
com binations of these alloys are
possible. W elding consum ables
are not available in exactly the
sam e chem ical com position as
the base m etal to be joined.
There are w ires and rods in the
4XXX and 5XXX series, nam ely
4043A , 4045, 4047A , 5183,
5356 and 5556A in the m arket
(see also ISO 18273). In the Table
VIII.2 , w ith the recom m endation
of the best suited w eld consum -
able, w e distinguish betw een dif-
ferent requirem ents for the w eld:
optim al strength, good corrosion
resistance and w eldability. A
choice m ust be m ade according
to the relative im portance of
these three requirem ents.
The w eld consum ables should be
stored in their sealed package
and once a package is open, it
should be kept in a dry atm os-
phere, because hum idity on the
surface of the w ire or rod causes
porosity in the w eld. If open reels
of filler w ire are exposed to
am bient clim atic conditions for a
longer period (m onths), it is rec-
om m ended to dry them in a
w arm ing box at approx. 80
°
C for
one night before use.
SELEC TIO N O F W ELD IN G PRO C ESS
TABLE VIII.3
Process TIG M IG
A tm osphere Inert Inert
Electrode Refractory C onsum able
C urrent A .C . D .C . Sm ooth Pulsed Pulsed Pulsed
Special effect W ire pulsation C old M etal Transfer
Suitability
Thickness range (m m ) 0.8 ≤ t ≤ 5 0.2 ≤ t ≤ 10 3 ≤ t 2 ≤ t 1 ≤ t ≤ 5 t ≤ 1
M anual yes no yes yes difficult no
A utom atic yes yes yes yes yes yes
Industrial robot no no yes yes yes yes
3.9. Sel ect i on of w el di ng pr ocess
3.8. Choi ce of f i l l er w i re or rod
117
EUROPEAN ALUMINIUM ASSOCIATION
This process com bines the high
m elting capacity of the M IG
process w ith the nearly ideal
shape of the plasm a arc and its
very good gas shield for the
w elding pool. The result is an
extrem ely good quality of w elds,
especially the absence of porosi-
ty. The plasm a arc is m aintained
betw een the plasm a ring nozzle
of the torch and the w ork piece,
the M IG arc is in the centre of
the plasm a arc. Both arcs have
the sam e polarity w here the high
kinetic energy of the plasm a arc
destroys the oxide layer on the
w ork piece. M echanical rem oval
of the oxide layer can be dis-
pensed w ith.
The process is w ell suited for
applications w ith high require-
m ents for tightness and surface
aspect. It is possible to carry out
butt w elds of up to 10 m m thick-
ness in one pass w ith the edge
preparation in V. The w elding
speed is higher than for M IG
w elding.
4. Pl asma MIG wel di ng
5. Laser wel di ng
Laser w elding of alum inium
alloys is developing rapidly paral-
lel w ith the developm ent of ever
grow ing pow er of laser sources.
There are on one side C O
2
lasers
of up to 20 KW and m ore and
N d:YA G lasers of 6 KW and
m ore. W ith the C O
2
laser, the ori-
entation of the beam is lim ited,
w hereas w ith the N d:YA G laser
optical fibres allow to bring the
laser beam directly to the w eld
zone. This gives high flexibility
especially for robot w elding. The
high reflectivity of alum inium
m akes it necessary to install the
laser equipm ent in a separate
room , w here during operation of
the equipm ent, nobody w ithout
adequate eye protection has
access. The sensor w hich em its
the signals necessary for the
m otion control of the laser beam
m ust be very effective for not
being disturbed by reflections.
The process is m ainly used for
thin gauge m aterials (1 –4 m m )
and the pieces to be joined m ust
fit perfectly as is the case e.g. in
the production of tailored blanks
for the car industry.
The achievable w elding speeds
are up to 12m /m in w ith thick-
ness of around 1m m and still
1-3 m /m in w ith thicknesses
betw een 1.5 and 3 m m .
C om pared w ith standard arc
w elding, laser w elding allow s the
production of com ponents w ith
reduced geom etrical distortions
and residual stresses, as w ell as
narrow er heat affected zone, a
direct consequence of the high
w ork speed and thus the low
heat input.
The laser w elding process is
preferably used w ith filler w ire
for alum inium alloys.
118
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 118 | 119
6. Laser MIG wel di ng
The com bination of a standard
arc w elding process w ith the
laser w elding process allow s to
benefit from the advantages of
both processes, w hich are good
process stability, high w elding
speed and enhanced bridging
capacity.
The laser beam runs ahead of the
M IG arc but both focus on the
sam e point of the m etal surface.
The shielding gas is provided by
the M IG torch. Preferably a m ix-
ture of helium (70% ) and argon
(30% ) is used. This process is
ideal for continuous autom atic
w elds up to 10 m m thickness in
one pass, w here the require-
m ents for fit up of the pieces to
be joined is less stringent than
for pure laser w elds.
The sam e safety m easures as for
laser w elding m ust be applied.
Laser w el di ng
119
EUROPEAN ALUMINIUM ASSOCIATION
This technique is very com m on in
the autom otive industry and not
so w idespread in the C om m ercial
Vehicles industry.
For this reason, w e do not give
details here.
Interested readers should refer to
the Alum inium Autom otive M anual:
w w w .eaa.net/aam
7. Resi stance wel di ng
This is an innovative process
w hich had been developed by
TW I Ltd (The W elding Institute)
and is protected by patents in
Europe, U SA and A ustralia.
A nyone using the process needs
a license from TW I.
The process operates in the solid
phase of the m etal below the
m elting point of the alloy. A tool
in the form of a finger w ith a
shoulder is rotated and m oved
into the m etal w ith a defined
rotational speed along the con-
tact line betw een the tw o parts
to be joined. The friction of the
tool in the m etal supplies the
needed energy to heat the local
zone to the desired tem perature.
Through the rotation and the
translation of the tool the m ate-
rial in the w eld zone is plastically
deform ed to create the w eld.
The process can be used for butt
w elds, overlap w elds, T –sec-
tions and corner w elds. For each
of these joint geom etries specific
tool designs are necessary. The
process can be used in all posi-
tions i.e. horizontal, vertical,
overhead and orbital.
The process can be used for
w elds up to 50 m m thickness
from one side and up to 100 m m
from tw o sides. A dvantages are:
•H igh productivity, i.e. low cost
potential
•Low distortion, even in long
w elds
•Excellent m echanical proper-
ties as proven by fatigue, tensile
and bend tests
•N o fum e
•N o porosity
•N o spatter
•Low shrinkage
•C an operate in all positions
•Energy efficient
•N o consum able tool ( one tool
typically can be used for up to
1000 m of w eld length in 6000
series alloys)
•N o filler w ire
•N o gas shielding
•N o w elder certification
•Som e tolerance to im perfect
w eld preparations –thin oxide
layers can be accepted
•N o grinding, brushing or pick-
ling required in m ass production
8. FSW - Fri cti on Sti r Wel di ng
Fri ct i on St i r Wel di ng
120
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 120 | 121
The lim itations of the FSW process
are continuously reduced by inten-
sive research and developm ent.
H ow ever, the m ain lim itations of
the FSW process are at present:
The relatively high investm ent
requires a high degree of
repeatability in order to m aterial-
ize the cost saving potential
W ork pieces m ust be rigidly
clam ped
Backing bar required (except
w here self-reacting tool or direct-
ly opposed tools are used
Keyhole at the end of each w eld
C annot m ake joints w hich
require m etal deposition (e.g. fil-
let w elds)
U p to now the dim ensionally
biggest equipm ent can cope
w ith w ork pieces up to 20 m
long.
Fri ct i on st i r w el ded t ai l l i f t prof i l es
121
EUROPEAN ALUMINIUM ASSOCIATION
9. Surf ace preparati on bef ore wel di ng
For quality w elds it is recom -
m ended to m achine the edges
(see section 3.7) of sheet to be
w elded after w ater jet, plasm a or
laser cutting to rem ove this
rough surface w ith a thick oxide
layer and also w ith m icro cracks
in order to avoid w eld defects
such as cracks and oxide inclu-
sions. The sam e should be done
for plate w ith thickness over 10
m m that has been sheared.
There is a great risk of cracks in
the short transverse direction,
w here a rem oval of 2 m m via
m illing or routing is adequate.
The m etal to be w elded m ust be
dry and w ithout contam ination
of any grease or other products
that evaporate under the action
of the arc. To achieve this clean
surface, the pieces to be w elded
should be brought into the w ork-
shop tw o days before produc-
tion. This w ill allow condensation
that m ight occur w hen the tem -
perature in the storage area is
low er than in the w orkshop to
dry off.
Im m ediately before w elding, the
edges to be joined and their sur-
roundings m ust be properly
degreased using a solvent such
as acetone or industry alcohol.
A void trichlorethylen, w hich
transform s under the effect of
the arc into the poisonous gas
phosgene. W hen the solvent on
the surface has evaporated, a
further cleaning w ith a stainless
steel w ire brush (hand-operated
or rotary) is recom m ended.
O utdoor w elding is not advis-
able. If it cannot be avoided, the
w elding environm ent m ust be
screened off.
Wel di ng of t i pper body (SCHMITZ)
122
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 122 | 123
10. Qual i ty control
Q uality control enables m anufac-
turers to judge the quality of the
products they fabricate and m ore
specifically to grade the quality
of a w elded joint against an
acceptable level of defined
defects.
The level of acceptable defects is
determ ined by:
•the types and directions of
load (static and dynam ic),
•the levels and variations in
stress,
•possible hazards to personnel,
•the technical and financial
im pact of the failure of the w eld-
ed structure,
•the possibility of routine oper-
ational inspection and control.
10.1. Approval procedures
The procedures are either con-
tractual betw een client and sup-
plier or self-regulated by the fab-
ricator. W elders m ust be certified
and qualified in accordance w ith
EN ISO 9606-2. W elding proce-
dure specification m ust be in
accordance w ith EN ISO 15609-
1, EN ISO 15612, EN ISO 15613
and EN ISO 15614-2.
Test specim ens m ust be subm it-
ted for tensile or bending tests.
Bending tests are im portant
because they:
•detect bonding that is hard to
identify in non-destructive testing,
•help achieve a good balance
of param eters w ith a view to pre-
venting these defects.
The type of inspection carried
out on w elded joints w ill natural-
ly depend on the w ork rate of
the w eldm ents.
In the fabrication shop it is possi-
ble to perform the follow ing
non-destructive tests (N D T) in
addition to visual inspection:
•dye penetration tests are valu-
able for detecting leaks and
em ergent cracks,
•w eld shape tests (geom etrical
shape),
•radiography, used to detect
internal defects (porosity, cracks,
inclusions) in butt joints,
•ultrasonic tests
It m ay also be prudent to per-
form som e destructive tests on
reference specim ens.
A n inspection plan m ust be
m ade containing:
•extent of inspection before
w elding
•extent of inspection and N D T
•N D T m ethods to be used
•acceptance criteria (quality level)
in accordance w ith EN ISO 10042
10.2. I nspect i ng w el ded j oi nt s
123
EUROPEAN ALUMINIUM ASSOCIATION
W eld defects and quality levels
are given in EN ISO 10042.
G uidance for choice of quality
level is given in EN 1090-3.
A n international nom enclature of
defects has been established and
is given in EN ISO 6520-1 w hich
lists 6 groups of im perfections:
•G roup 100: C racks
•G roup 200: C avities and
w orm holes
•G roup 300: Solid inclusions
•G roup 400: Lack of fusion and
penetration
•G roup 500: D efects of shape
•G roup 600: Sundry defects
LISTS SO M E C O M M O N W ELD D EFEC TS A N D TH EIR C A U SES
TABLE VIII.4
N° Type of D efect Likely C ause Photos of Im perfections
101 C racks Base alloy unsuitable
Poor choice of filler m etal
Incorrect w elding sequence
Excessive clam ping
Sudden cooling
104 C rater cracks Pass finished w ith sudden arc cutoff
2012 Irregular w orm holes W ork inadequately degreased
W ork and/or filler w ire dirty or w et
Insufficient protection by inert gas
(low gas flow or leak in the system )
Pass begun on cold com ponent
H igh arc voltage
W eld cooled too quickly
2014 A ligned w orm holes Incom plete penetration (double pass)
Tem perature gradient betw een
backing and w ork too abrupt
Excessive gap betw een edges of the joint
300 Solid inclusions D irty m etal (oxides, brush hairs)
303 O xide inclusions Poor gas shielding
M etal stored in poor conditions
C astings
Defect 104
Defect
2012
Defect 101
10.3. Wel d def ect s & appr oval cr i t er i a
124
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 124 | 125
N° Type of D efect Likely C ause Photos of Im perfections
3041 Tungsten inclusions Electrode diam eter too sm all
(TIG ) Poor handling by w elder
Excessive current density
Poor quality of tungsten electrode
402 Incom plete penetration Inadequate cleaning (presence of oxide)
Incorrect bevel preparation on thick w ork
(too tight, excessive shoulder)
G ap betw een w orkpieces too sm all
(or incon-sistent)
Low current, especially at the start
of the seam
W elding speed too fast
H igh arc voltage
4011 Lack of fusion H igh arc voltage
on edges Low current, especially at the start
of the seam
W ork cold (difference in thickness
betw een m aterials to be w elded)
502 Excessive thickness Poor pow er control
(poor U /I m atch)
W elding speed too slow
Poor edge preparation on thick w ork
Insufficient starting current
507 M isalignm ent W ork positioned incorrectly
Incorrect w elding sequence
508 A ngle defect Excessive w elding pow er
Incorrect w elding sequence
509 C ollapse W ire speed too fast
Torch speed too slow
Poor torch guidance
602 Splatter (or beads) Incorrect arc control
Problem in electrical contact to ground
Defect 402
Defect 502
Defect 507
Defect 402
Defect 300
125
EUROPEAN ALUMINIUM ASSOCIATION
11.1. Causes
of def or mat i on
In m achine w elded structures,
deform ation can be caused by:
11.1.1. The direction
of the welds
It is a w ell know n fact that a bead
contracts m ost at the end of the
w eld, w hich is w hy the greatest
deform ation occurs in the end
zones. So far as possible therefore
it is essential to orient the w eld
tow ards the outside of the w ork-
piece so as to release as m uch
stress as possible. O therw ise, w ith
the w eld facing the m iddle of the
com ponent, the contraction
stresses are “trapped”and defor-
m ation w ill be greater as a result.
The end of the w eld m ust be fin-
ished to prevent any danger of
cracking on the end crater.
11.1.2. The effect of punching
This is norm ally due to design
error. If w e take the exam ple of a
bulkhead inside a tank, it is
essential that the bulkhead,
w hich is either deep-draw n or
spun, has a dow n flanging rest-
ing flat against the body of the
tank and by w hich the bulkhead
is w elded to it. This approach
should prevent the problem of
punching due to the w eld con-
tracting and should m inim ise
deform ation (Figure VIII.4).
Sim ilarly, w here the body of a
tank has to be stiffened, it is
essential to place a support plate
betw een the stiffener and the
skin of the tank to prevent defor-
m ation by the effect of punching
due to w eld contraction (Figure
VIII.5). In the absence of a sup-
port plate the tank w ould
deform under the effect of sub-
sequent dynam ic stresses.
11.2. Sol ut i ons
There are a num ber of solutions
to the above problem s:
11.2.1. Use of extrusions
It is w orthw hile using extrusions
in the fabrication of chassis as
this can help to:
•position assem blies in less
stressed areas,
•m ake w elds that elim inate
deform ation.
11. Desi gn and preventi on of def ormati on
U PSTA N D W ELD IN G
FIGURE VIII.4
®
U pstand
126
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 126 | 127
C hassis side m em bers for
instance are usually fabricated
from tw o extrusions form ing the
tw o flanges of the m em ber and
a sheet for the w eb.
The assem bly show n in Figure
VIII.6 can be autom atically M IG
w elded w ith tw o w elding torch-
es operating sim ultaneously.
Both m ethods of butt joining are
possible, i.e. w ith the side m em -
ber positioned vertically or hori-
zontally. The choice of position
w ill be dictated chiefly by the
design of the w elding bench.
W hen the side m em ber is hori-
zontal a support w ill be needed
to counteract angular deflection.
11.2.2. End stops
These m ust be positioned so as
to allow free elongation of the
assem blies during w elding.
"C om pressing" a w eld, i.e. pre-
venting its elongation, greatly
exaggerates contraction and
hence subsequent deform ation.
11.2.3. Predeforming
Som e w eld deform ations can be
offset by predeform ing the areas
to be w elded in such a w ay that
the assem bled com ponents
"com e right" after w elding.
If the m etal is only predeform ed
in the elastic zone by clam ping,
the results can be very erratic,
and it is therefore advisable to
predeform by bending the m etal
in the plastic zone. In this w ay,
the results w ill be predictable
and repeatable.
W ELD IN G W ITH SU PPO RT PLATE
FIGURE VIII.5
FA BRIC ATIN G A C H A SSIS M EM BER
FIGURE VIII.6
H orizontal (flat)
Vertical
(flat)
®
®
®
®
127
EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION
128
CHAPTER I X
OTHER JOI NI NG
TECHNI QUES
1. ADHESIVE BONDING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
1. 1. Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130
1. 2. Advantages and disadvantages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
1. 3. Types of adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 131
1. 4. Application of adhesives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132
1. 5. Creep and ageing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
2. SCREWING AND BOLT FASTENING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
3. RIVETING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
4. SNAP-LOCK & CLIPPING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135
129
EUROPEAN ALUMINIUM ASSOCIATION
1.1. Def i ni t i on
A dhesive bonding is defined as
a process of joining parts using a
non-m etallic substance (adhe-
sive) w hich undergoes a physical
or chem ical hardening and by
thus leading to a joining of the
parts through surface forces
(adhesion) and internal forces
(cohesion).
A dhesion can be physical attrac-
tion betw een the adhesive and
the m etal surface, real chem ical
bonding betw een the adhesive
m olecules and the m etal atom s
or m echanical interlocking
betw een the adhesive and the
surface roughness of the m etal.
C ohesion is the inner strength
of the adhesive itself as a result
of physical and/or chem ical
forces betw een the com ponents
of the adhesive.
1. Adhesi ve bondi ng
Physi cal at t ract i on f orces
bet w een adhesi ve and
met al surf ace
Chemi cal bondi ng
bet w een adhesi ve
mol ecul es and met al
at oms
Mechani cal i nt erl ocki ng
bet w een adhesi ve and
surf ace roughness of
t he part s t o be j oi ned
Physi cal and/or chemi cal i nt eract i on
bet w een t he adhesi ve mol ecul es
PRINCIPLE OF ADHESIVE BONDING
FIGURE IX.1
ADHESION
COHESION
Source: Talat lectures
130
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER I X OTHER JOI N I N G TECHN I QU ES 130 | 131
1.2. ADVANTAGES AND DI SADVANTAGES
Advantages
1. Load distributed uniformly at right
angle to loading direction
2. Microstructure unaffected
3. Distortion-free joining
4. Different materials can be joined
5. Very thin parts can be joined
6. Weight saving
7. Heat-sensitive materials can be joined
8. Metals with different electrochemical
potentials can be joined (insulating
effect of adhesive)
9. High strength joining in combination
with other methods (screwing,
welding…)
10. High fatigue strength and good
vibration damping
Disadvantages
1. Influence of time on process properties
2. Pre-treatment of joined surfaces
necessary
3. Limited form stability
4. Process parameters must be held in
narrow ranges
5. Change of the properties in time
(ageing of the adhesive)
6. Complicated control of process
7. Low peeling strength
8. Low adhesive layer strength requires
large joining areas
9. Limited repair possibilities
10. Difficult strength calculation
Source: Talat lectures
1.3. Types of adhesi ves
Adhesives can be divided into 3 sub-
groups depending on their form ing
reaction and polym er structure:
•Polym erisation: A n exotherm ic
process in w hich m onom ers link
together to form m acrom olecules
(polym ers). Therm oplastics like
m ethylacrylates, polyvinyl chlo-
rides, polyvinyl acetates and rub-
ber polym ers belong to this group
•Polycondensation: W ater is pro-
duced as a result of the chem ical
reaction. Therm oplastics like
polyam ides and polysulfones as
w ell as durom ers like phenol
form aldehyde resins, urea resins,
m elam ine resins and polym ides, are
all produced by polycondensation.
•Polyaddition: D uring this
process the hydrogen atom s are
rearranged. Very com m on adhe-
sives for m etal bonding like
epoxy resins and polyurethanes
are produced by polyaddition.
C om bination of adhesive bonding
and m echanical joining (e.g. rivet-
ing or bolting) can elim inate som e
of the above-listed disadvantages.
131
EUROPEAN ALUMINIUM ASSOCIATION
1.4. Appl i cat i on
of adhesi ves
A s adhesive bonding is w orking
by surface forces, prerequisites
for a w ell functioning adhesive
joint are
a) the choice of an appropriate
adhesive for the m aterials to be
com bined
b) the existence of a suitable
m aterial surface
A suitable surface m eans, that
the surface area m ust be large
enough to transfer the applied
forces and that it is capable to
ensure a proper bonding. This
can be achieved through a
suitable pre-treatm ent. A ny
residues of dirt like m oisture,
oils, dust etc. m ust be rem oved
prior to application of the adhe-
sive. This can be done by chem -
ical m eans w ith the use of
detergents, degreasers or etch-
ing agents or m echanically by
grinding. In any case the surface
m ust be absolutely clean before
gluing. It m ight be favourable to
use a prim er for better w etting
of the m etal surface by the
adhesive as w ell.
The joint construction should be
related to the adhesion process
and its requirem ents for large
bonding areas. Peeling and
cleaving forces on adhesive
joints m ust be avoided and
bending forces should be
reduced to a m inim um .
The adhesive can be applied
m anually (e.g. w ith the use of
cartridges) or for larger areas
w ith autom ated m achines. The
bonding should take place in a
dry and w ell ventilated and
dust-free w orkshop.
The w ork m ust be done in strict
com pliance w ith the m anufactur-
er´s rules. The production param -
eterssuch as resin/hardenerratio,
duration and pressure com ponent
fit up during adhesive curing,curing
tem perature, etc. m ust be con-
trolled properly.
1.5. Cr eep and agei ng
The durability of adhesive joints
depends on factors such as prop-
er pre-treatm ent, chem ical com -
position of the adhesive and
service conditions like stresses,
tem perature, hum idity and expo-
sure to ultraviolet radiation (poly-
m ers are sensitive to this kind of
radiation and tend to lose their
m echanical properties).
The ageing of bonded joints can
be caused by creep under stress
(creep can be defined as tim e-
dependent increase in the
length of visco-elastic sub-
stances subject to a constant
tensile load).
A dhesive joints should therefore
be inspected regularly to pre-
vent dam ages and to enable
repair prior to a possible failure.
Prot ot ype f l oor sect i on made
of bonded sheet s and ext ruded
st i f f eners
Patented by A lcan
132
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER I X OTHER JOI N I N G TECHN I QU ES 132 | 133
Bolting creates a joint w hich can
be opened and closed as m any
tim es as necessary. It is besides
w elding the m ost conventional
m ethod for joining m etals. In
contradiction to w elding, differ-
ent m etals can be joined. In
com m ercial vehicles this is m ost
likely the connection betw een
steel and alum inium (e.g. the
connection betw een chassis and
tank or tipper body). Special
precautions should be taken to
avoid galvanic corrosion, please
refer to C hapter XI.
The choice of the fastening
geom etry w ill depend on the
result of the calculation of the
applied stresses. In the com bina-
tion of steel screw s w ith alum ini-
um plates, the risk of galvanic
corrosion m ust be considered:
insulating gaskets should be
placed around the contact area
betw een both m etals.
2. Screwi ng and bol t f asteni ng
Riveting is today a w idespread
joining m ethod in different sec-
tors of industry, including com -
m ercial vehicle construction. A s
it is a very safe and easy-to-
apply technique, riveting has
becom e a very com m on m ethod
for joining assem blies e.g. in the
construction of the bodies of
refrigerated trailers.
M achine riveting has a lot of
advantages:
•H igh-speed: M achine riveting
allow s fast operations w ith the use
of pneum atic or hydraulic tools
•Ease of control: the clam ping
force is alw ays guaranteed by
the system as it is less than the
force needed to snap the rivet
•O ptical appearance: M achine
riveting can be com bined w ith a
plastic capping of the rivet
•It does not require skilled
operators
•M ixed joints are possible: dif-
ferent m etals, plastics, sandw ich
or honeycom b panels
Rivets can be divided into
2 m ain subcategories: self pierc-
ing rivets and conventional riv-
ets w hich require holes that
m ust be drilled prior to riveting.
C onventional can be sorted into
tw o fam ilies:
•Lockbolts w hich visually look
like they create the sam e type of
connection as a conventional
bolt, but unlike conventional
nuts and bolts; they w ill not
w ork loose, even during
extrem e vibration. They can only
be used w hen both sides of the
joint are accessible. Lockbolts
consist of a pin w hich is inserted
in the hole and a collar w hich is
placed on the pin from the
opposite end. The tool is placed
over the fastener pintail and
activated, the pin head pulls
against the m aterial, the tool
anvil then push’s the collar
against the joint, at this stage
the initial clam p is generated.
The tool then sw ages the collar
into the pin. The pintail then
breaks and the installation is
com plete (Figure IX.2).
3. Ri veti ng
133
EUROPEAN ALUMINIUM ASSOCIATION
Lockbolt strength
characteristics
Clamp force or pre-load: dur-
ing the installation process, as
the tool engages and pulls on
the pintail, the joint is pulled
together before the conical
shaped cavity of the nose
assem bly is forced dow n the
collar, progressively locking
(sw aging) it into the grooves of
the harder pin. The pin and
sw aged collar together form
the installed fastener.
The squeezing action reduces
the diam eter of the collar,
increasing its length, w hich in
turn stretches the pin, generat-
ing a clam p force over the
joint.
Shear strength of lockbolts
varies according to the m ateri-
al strength and m inim al diam -
eter of the fastener. By increas-
ing the diam eter or the grade
of m aterial, the shear strength
of the fastener can be
increased.
The tensile strength of lock-
bolts is dependent on the
shear resistance of the collar
m aterial and the num ber of
grooves it fills.
•Blind rivets, w hich are used
w hen only one side is accessible.
Blind rivets are characterised by
breaking off of the rivet stem
after fastening the connection by
LOCKBOLTS
FIGURE IX.2
BLIND RIVET
FIGURE IX.3
SELF-PIERCING RIVET
FIGURE IX.4
deform ation of the rivet (there-
fore they are often called
“breakstem rivets”). (Figure IX.3)
•Self piercing rivets do not
require previous drilling. The
rivet part of the bolt is pierced
through the m etal sheet. The
further closing m otion of the
tool, together w ith the specially
shaped counter die causes the
rivet head to be form ed in such
a w ay that the pierced sheet is
covered over in the joining
region. (Figure IX-4).
134
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER I X OTHER JOI N I N G TECHN I QU ES 134 | 135
The Snap-Lock is a design w hich
uses serrated com ponents m ak-
ing assem bly easy and quick.
The snap-lock design allow s sid-
ing to be notched and locked
into place w ithout face nailing.
Stresses are distributed over the
entire length of the profile and
not m erely concentrated on the
m echanical fixing point (rigidity).
4. Snap-l ock & cl i ppi ng
CLIPPING PRINCIPLE
FIGURE IX.5
Reef er f l oor assembl ed
by bondi ng (Schmi t z)
135
EUROPEAN ALUMINIUM ASSOCIATION
136
CHAPTER X
DECORATI ON
AND FI NI SHI NG
1. FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
2. POSSIBILITIES WITH ALUMINIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 138
3. MECHANICAL FINISHING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3. 1. Brushing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
3. 2. Polishing /Buffing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 139
4. CHEMICAL DECORATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
4. 1. Anodizing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
4. 2. Painting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 141
137
EUROPEAN ALUMINIUM ASSOCIATION
There are several m ethods for
decoration and finishing of an
alum inium surface. A lthough all
of the m ethods used for other
m aterials are applicable, special
attention has to be paid to alu-
m inium ´s characteristic proper-
ties. In each case, especially the
softness of the surface and the
existence of the oxide layer have
to be considered.
There are 2 m ain m ethods of
decoration and finishing:
•M echanical finishing
- Brushing
- Polishing (or “buffing”)
•C hem ical Finishing
- A nodising
- Painting
Today, painting is the m ost com -
m on w ay to decorate trucks and
trailers.
A lthough alum inium can be used
w ithout any surface protection
and keeps its natural beauty
throughout a w hole trailer life, it
is m ost likely to use different sur-
face treatm ent m ethods to opti-
m ise the attractiveness and opti-
cal appearance of a trailer, to pro-
tect it from severe atm ospheric
conditions and to give space for
com pany logos or advertise-
m ents.
1. Foreword
2. Possi bi l i ti es wi th al umi ni um
Al umi ni um t anker (Trai l or)
138
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X DECORATI ON A N D FI N I SHI N G 138 | 139
3.1. Br ushi ng
Brushing is a rather seldom ly
used m ethod for the decoration
of trucks and trailers. It can
m ostly be seen on tankers for
the transport of fluid goods.
Like polishing, brushing is based
on abrasion effects betw een the
brush surface and the alum ini-
um surface. D ue to the brush
being the harder part, alum ini-
um is rem oved from the surface
by an abrasive effect. Brushing
is done w ith rotary brushing
tools or m achines. N orm ally no
additional brushing com pounds
or chem icals w ill be used.
Like for every surface treatm ent of
alum inium , the part to be brushed
has to be cleaned and degreased
properly before applying the
brushing process. The cleaning is
done to rem ove any dust, dirt, oil,
em ulsion or other residues from
the rolling process prior to brush-
ing and to prevent particles from
being squeezed into the surface
during brushing. To secure a uni-
form surface appearance, it is of
great advantage to use an auto-
m atic process w ith several brushes
in one single station, w hich are
sim ultaneously controlled.
3.2. Pol i shi ng / Buf f i ng
Polishing or buffing is a quite
com m on m ethod in the N orth
A m erican m arket to provide a
decorative surface finish. 3 m ain
m ethods can be applied:
•U se of m irror-finished alum ini-
um sheets and plates fabricated
in the rolling m ill
•Polishing / buffing of m ill finish
sheets to the desired surface
appearance
•M anual polishing
The use of m irror-finished plates
or the use of already buffed or
polished sheets has the advan-
tage, that the w ork on site is
reduced to the m anual polishing
of w eld seam s or places w hich
have been dam aged during fab-
rication. G reat care m ust be
taken w hen handling or w orking
w ith these sheets, as every little
trace of a m echanical defect
caused by fabrication m ust be
m anually polished.
M irror finished plates are fabri-
cated in the rolling m ill by the
use of a special rolling routine
w ith w ork rolls w hich have near-
ly no surface roughness. This
m akes it a very dem anding
process and great care m ust be
taken to secure a reliable and
constant quality of the sheets.
Buffing or polishing of large
plates is done on autom atic lines,
w here the surface is polished
w ith rotary polishers across the
w hole w idth of the sheet at the
sam e tim e. The rotary polishers
have special pads on their sur-
face, w hich polish the alum inium
surface under the help of polish-
ing com pounds. The polishing
com pounds w orks as a slight
abrasive and rem oves the top
layer of the alum inium surface in
the range of the surface rough-
ness produced by the rolling m ill.
A s the result of polishing is very
m uch depending on the type of
alloy and tem per, the surface
hardness, the type of polishing
paste and the m achine setting
(like rotational speed, pressure
and type of pad), this is a m ethod
of “trial and error”to find the
right setting per specification.
3. Mechani cal f i ni shi ng
139
EUROPEAN ALUMINIUM ASSOCIATION
In any case, before polishing, the
alum inium plates should be
degreased and cleaned to rem ove
any kind of dust and dirt to prevent
abrasive particles from being
ground into the alum inium surface.
The sam e rules apply for m anual
polishing. This process is difficult
to apply and a large and exten-
sive experience is necessary to
reach a satisfactory and repro-
ducible result. A fter rem oval of
surface dirt or oil, the m anual
process starts w ith a rotary pol-
isher and the use of quick- cut-
ting abrasive paste. The pad
should be a w ool com pounding
type. Speed of the polisher m ust
be lim ited to prevent burning of
the surface. The polisher should
be m oved back and forth, up and
dow n to ensure a uniform abra-
sion of the surface. A s the pad
w ill suddenly turn black (caused
by the polishing residue), great
care m ust be taken to regularly
clean or change the pad. A fter
the rough first polish, the type of
paste should be changed to one
w ith low er abrasion. Before
applying the final polishing step,
it is useful to clean the surface
again to rem ove the black
residue, w hich m ight be trapped
into the surface. The final result
of m anual polishing should be a
m irror-like, uniform , sw irl-m ark,
black speck- and bright sparkle-
free surface.
To keep the m irror-like surface
throughout a long period, it
m akes sense to apply a clear coat
system , as exposure to norm al
atm osphere w ould lead to a
bleaching of the polished surface.
Al umi ni um t i pper (Benal u)
Al umi ni um t ank (LAG)
140
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X DECORATI ON A N D FI N I SHI N G 140 | 141
4.1. Anodi zi ng
Anodizing is an electrochem ical pro-
cess to reinforce the natural oxide
film on the alum inium surface.
A nodising is done in a sulphuric
solution at a certain electric cur-
rent. The natural oxide film is
thereby new ly built and the
process can be controlled to reach
4. Chemi cal decorati on
STRU C TU RE O F TH E A N O D ISED LAYER
FIGURE X.1
®
®
N otch
Sealed
cells
A lum inium
Pore
C ell w all
Barrier layer
(base of the
cell)
®
®
®
®
®
certain thicknesses of the oxide
layer (in the range of 1000 tim es
of the natural oxide film ).
A nodising not only produces
m ost frequently a silver- m att sur-
face, but at the sam e tim e
enables increasing hardness, cor-
rosion resistance and resistance to
abrasion. The process is applied
discontinuously on com ponents
like castings, extrusions and plates
or continuously on coils.
The structure of the anodic film is
determ ined by the process
param eters (type of bath, applied
current etc.) and consists of
hexagonal cells. The center of the
cells includes a m icro-pore w ith a
diam eter of m icrom eters. These
pores have to be sealed to close
them and to guarantee an excel-
lent corrosion resistance. This is
done in boiling w ater under the
use of sealants. (Figure X.1)
4.2. Pai nt i ng
4.2.1. Introduction
Painting is the m ost usual w ay of
decoration for com m ercial vehi-
cles. D ue to the natural oxide
film on the alum inium surface, it
is of vital im portance for a w ell
adherent and durable organic
coating to apply an efficient sur-
face preparation.
It is therefore not sufficient to
clean the bare alum inium surface
and to degrease it prior to paint
application. It is essential to
rem ove also the natural oxide
layer, because it disturbs adhe-
sion of the paint system .
This can be done in 2 w ays:
Chemical pre-treatment
by etching (after degreasing
or by a combine
degreasing/etching process)
D egreasing of alum inium sur-
faces can be done w ith fluid
degreasing solvents, supplied
e.g. by paint producers. The
objective of cleaning and
degreasing are:
• to rem ove any kind of fatty or
oily residues, or traces of dirt and
dust from the surface
• to prevent electrostatic charging.
141
EUROPEAN ALUMINIUM ASSOCIATION
To apply a degreasing solvent
properly, it is necessary to w ipe
the surface w ith a fresh m ois-
tened cloth and then clean it
w ith a new , fresh and dry cloth.
A lum inium has am photeric prop-
erties, w hich m eans that it can
be dissolved either in an acidic or
alkaline environm ent. Etching of
com m ercial vehicles is norm ally
done by applying the etching
agent by spraying. A lkaline etch-
ing agents are based on caustic
soda, silicates, phosphates, car-
bonates and sodium hydroxide.
The concentration of sodium
hydroxide and the tem perature
of the etching agent have a large
influence on the speed and rate
of the etching process. Etching
can also be done on the base of
acidic solutions w ith phosphoric
acid or nitric acid. Etching leaves
a rough and very m oisture-sensi-
tive surface behind. It is therefore
essential to rinse carefully w ith
fresh w ater after etching (about
20 m inutes).
Mechanical treatment
sby grinding or blasting
G rinding is to be done on a clean
and degreased surface to prevent
oil being trapped into the alum ini-
um , w hich could lead to adhesion
problem s of the paint. The grain-
ing of the grinding disk should
have a grain size of 120-180.
Blasting allow s a m ore uniform
treatm ent of the vehicle and
reaches areas w hich cannot be
reached by a m anual grinding
m achine. It is essential to use
iron-free blasting abrasives like
non-recycled corundum , as iron
can lead to corrosion problem s
1
.
The rate of abrasion during blast-
ing is very low and w ell below
0.1 m m and therefore in the
sam e range as etching.
A fter grinding (w hich is also used
to flatten the w elding seam s and
to plane out scratches) or blast-
ing it is necessary to rem ove
traces of the abrasives by com -
pressed air and then to clean the
surface again.
1. The incrustation of iron particles on
the alum inium surface is a source of gal-
vanic corrosion that w ill lead, in the
presence of m oisture, to superficial
m icro-pitting.
Cl eani ng bef ore pai nt i ng (LAG)
142
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X DECORATI ON A N D FI N I SHI N G 142 | 143
4.2.2. Application of the primer
The prim er should be applied
directly after the pre-treatm ent of
the surface to prevent the rebuild-
ing of the oxide film or to prevent
any dust being attracted by the
vehicle during longer periods of
w aiting tim e. Prim ers (or “w ash
prim ers”) are used as adhesive
agents to m aintain the necessary
bonding forces betw een the sub-
strate (alum inium surface) and the
paint system . They are also w ork-
ing as corrosion inhibitors, as they
prevent w ater vapour diffusion
through the paint system from
getting in contact w ith the alu-
m inium surface. Prim ers m ade of
epoxy- resins are a w ell suited
m aterial for pre-treating alum ini-
um , but need a thoroughly treat-
ed bare m etal surface. The prim er
is norm ally applied by spray gun
and the thickness of the w ash
prim er or reaction prim er layer is
about 10 µm .
4.2.3. Final coating
The application of the final coating
system can be done in different
w ays, but is anyhow not specific for
alum inium . In any case, it is of vital
im portance to use paint system s
w ith coordinated properties. The
technical rules of the paint suppliers
have to be strictly obeyed.
The final coating system can be sep-
arated into 2- or 3-layer system s
w ith or w ithout the use of fillers and
basecoats. Fillers are needed to flat-
ten unevenness and/or to increase
thickness of the coating system .
For preparation of the surface, the
prim er layer has to be ground w ith
a sm ooth grinding disk (roughness
300-400). Fillers have also to be
ground before application of the
topcoat system .
The paint is norm ally applied w ith
spray guns. Drying tim es and tem -
peratures have to be controlled. It
m ight be necessary to apply an
interm ediate fine grinding of the
single paint layers.
A typical painting procedure of a
silo tank trailer could be
2
:
•Etching / degreasing inside and
outside by spraying w ith an inhibit-
ed etching agent based on phos-
phoric acid
•Rinsing w ith fresh w ater for
about 20 m inutes
•Final assem bly of the vehicle
•G rinding of the tank surface w ith
a m anual grinding m achine to
rem ove sm all surface dam ages
•Cleaning and degreasing w ith
degreasers or silicone rem overs
•Application of the w ash prim er
onto the outer tank surface. Layer
thickness 8-10 µm .
•Drying of the tank at room tem -
perature (20°C) or at elevated tem -
peratures up to 80°C
•Rem oval of unevenness w ith a
filler; grinding of the filler layer
•Rem oval of dirt and dust by
w iping w ith a m oisturized cloth
•A pplication of the 1st paint
layer (basecoat or w et-in-w et
filler) in 2 steps w ith a com bined
layer thickness of 60-70 µm .
Special attention should be paid
to the area of stone chipping.
•A pplication of the topcoat
(clear-coat) in the desired colour
after m ax. 2 hrs. Final coating
thickness 50 –60 µm .
•D rying of the top layer
Extrusion profile system s used e.g.
in tipping trailers can be painted
in 2 w ays: either the trailer can be
painted as a w hole or the profiles
can be painted individually and
then being assem bled. The gener-
al rules for decoration m entioned
above are also valid for these
types of constructions.
In any case it is essential for a suf-
ficient and long lasting paint dec-
oration to apply a w ell conduct-
ed preparation of the surface as
m entioned before. Problem s w ith
the paint decoration often are
not related to the paint or the
alum inium itself, but m ore w ith
an insufficient pre-treatm ent.
2. Koew ius, G ross, Angehrn Aluminium-
Konstruktionen des Nutzfahrzeugbaus,
A lum inium Verlag, D üsseldorf, 1990.
143
EUROPEAN ALUMINIUM ASSOCIATION
144
1. DEFINITION OF CORROSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
2. CORROSION OF ALUMINIUM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
2. 1. The natural oxide layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 146
2. 2. Types of aluminium corrosion in commercial vehicles . . . . . . . . . . . . . . . . . . . . 147
2. 3. Further references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151
CHAPTER XI
CORROSI ON RESI STANCE
145
EUROPEAN ALUMINIUM ASSOCIATION
1. Def i ni ti on of corrosi on
C orrosion is a electrochem ical
interaction betw een a m etal and
its environm ent w hich results in
changes in the properties of the
m etal and w hich m ay often lead
to im pairm ent of the function of
the m etal, the environm ent, or
the technical system of w hich
these form a part (definition as
per EN ISO 8044).
C orrosion can occur locally (“pit-
ting”), or it can extend across a
w ide area to produce general
deterioration.
2. Corrosi on of al umi ni um
2.1. The nat ur al oxi de l ayer
A clean alum inium surface is very
reactive and w ill react sponta-
neously w ith air or w ater to form
alum inium oxide. This oxide
builds a natural protective layer
on each alum inium surface w ith
a thickness of around 1 –10 nm .
The oxide layer is chem ically very
stable, has a good adhesion to
the m etal surface, repairs itself
and protects the alum inium from
further corrosion. (Figure XI.1)
The oxide layer can be destroyed
in strong acidic or alkaline envi-
ronm ents or w here aggressive
ions are present. A ggressive ions
can destroy the layer locally and
lead to local corrosion attack
(“pitting”). A typical case for this
reaction is the contact betw een
alum inium and chloride ions,
w hich are present in seaw ater or
road salts.
Som e alloying elem ents m ight
increase the corrosion resistance
of the oxide layer, w hile others
can w eaken it.
Vehicle m anufacturers or fleet
operators should contact the alu-
m inium supplier in any case of
critical w orking conditions like
elevated tem peratures or aggres-
sive loads.
Aluminium substrate
Natural oxide
layer (Al
2
O
3
)
FIGURE XI.1
146
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X I CORROSI ON 146 | 147
A lthough highly resistant to cor-
rosion through its natural oxide
film , the follow ing types of corro-
sion can occur in com m ercial
vehicle construction or operation:
•G alvanic corrosion
•C revice corrosion
•Pitting corrosion
•Filiform corrosion
2.2.1. Galvanic corrosion
G alvanic or bim etallic corrosion
can occur w hen tw o different
m etals (or electroconductive
non-m etallic m aterials) com e
into direct or indirect contact
w ith each other in the presence
of an electrolyte. The reason for
this type of corrosion is the dif-
ference in the electrochem ical
potential of the tw o m etals.
A lum inium is a very electronega-
tive m etal and therefore special
attention has to be paid w hen
alum inium is used in com bina-
tion w ith other m etals under the
presence of an electrolyte (such
as w ater). In an electrochem ical
reaction, the alum inium is w ork-
ing as an anode and is dissolving,
w hile the other m etal retains its
integrity.
In this case, the alum inium ions
react w ith the oxygen of the
w ater to alum ina (A l
2
O
3
), w hich
builds a w hite layer on the alu-
m inium surface.
2.2. Types of al umi ni um cor r osi on i n commer ci al vehi cl es
147
EUROPEAN ALUMINIUM ASSOCIATION
There are 3 m ain prerequisites for
galvanic corrosion:
•2 different m etals w ith differ-
ent electrochem ical potential
•presence of an electrolyte
•direct or indirect contact
betw een the 2 m etals
The electrolyte enables the flow
of electrons betw een the 2 m et-
als. This can happen if the m etals
are w etted by the electrolyte
(e.g. w ater containing salt) or
em erged in the electrolyte. In
com m ercial vehicles, this type of
corrosion can occur w here steel
and alum inium parts are bolted,
riveted or screw ed together and
w here rainw ater or road splash
w ater can com e in contact w ith
the m etal parts. (Figure XI.2)
To avoid direct contact betw een
the 2 m etals and to prevent
entrapm ent of w ater, it is neces-
sary to w ork w ith insulating
m aterial (such as neoprene or
other elastom ers) betw een the
m etals and to use sealing com -
pounds to close constructive
gaps. (Figure XI.3)
PRINCIPLE OF A GALVANIC CELL BUILT WITH ALUMINIUM
AS ANODE
FIGURE XI.2
Electron Flow
Electrolyte
Cathode
(e.g. copper)
Anode
(Aluminium)
2Al 2Al
3+
+ 6e
-
6H
+
+ 6e
-
3H
2

®
®
®
A lum inium
G asket (PVC ,
elastom er)
O ther m etal
(Steel…)
Bolt
®
®
®
Sleeve and
insulating
w ashers
PREVEN TIO N O F G A LVA N IC C O RRO SIO N
FIGURE XI.3


e
-
148
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X I CORROSI ON 148 | 149
2.2.2. Crevice corrosion
C revice corrosion occurs in sm all
constructive recesses. In a crevice
there w ill be the possibility for
accum ulation of m oisture
because of capillary forces and
deposits of aggressive m edia.
Therefore, especially in the road
w ater splash zone, constructive
gaps should alw ays be closed as
far as possible, as the penetrat-
ing w ater m ight contain aggres-
sive ions (e.g. from road salts).
The corrosion rate of crevice cor-
rosion is norm ally very low due to
the corrosion product –alum ina
–being very stable and building a
sealing of the crevice. (Figure
XI.4)
2.2.3. Pitting corrosion
Pitting corrosion is the m ost com -
m on corrosion form seen on alu-
m inium , characterised by the
developm ent of sm all local pits in
the surface. The diam eter and the
depth of the pits varies and
depends on different param eters
related to the alum inium itself
(type of alloy, rate of cold w orking,
heat treatm ents) or to its environ-
m ent (presence of aggressive ions).
Pitting corrosion occurs on sites
w here the natural oxide film is
dam aged or im perfect due to
diverse reasons like m anufactur-
®
®
®
Sealing of access
to crevice
Possible
crevice
Sealing of the
crevice itself
Tight fastening
of bolts and rivets
necessary
CREVICES AND HOW TO PREVENT THEM
FIGURE XI.4
ing related circum stances (areas
w hich have been ground, w eld
discontinuities etc.). The pits are
form ed w ith a rapid increase in
depth after initiation follow ed by
a slow er grow th. This is due to
the corrosion product - alum ina –
that is not soluble in w ater and
therefore adheres to the surface
of the m etal inside the pits. The
alum ina then obstructs the direct
contact betw een the alum inium
surface and the corrosive m edi-
um and by this slow s dow n the
corrosion speed. (Figure XI.5)
This slow dow n in the rate of pit-
ting corrosion explains the fact
that alum inium equipm ent can be
used for decades in certain envi-
ronm ents (country air, sea air, sea
w ater) w ithout any protection.
In other w ords, pitting corrosion
is quite norm al and does not
im pact the durability of vehicles.
PITTING CORROSION
FIGURE XI.5
®
A
l
u
m
i
n
a
A
l
u
m
i
n
a
®
®
®
®
®
C I
-
C I
-
C I
-
C orrosion
A ttack
149
EUROPEAN ALUMINIUM ASSOCIATION
2.2.4. Constructive measures
to prevent corrosion
Som e general rules shall be
applied to prevent corrosion (in
m ost cases to prevent any kind of
w ater trap or areas w here con-
densation can occur):
•C onstructive gaps should be
avoided or, if not possible, should
be sealed. (Figure XI.6)
•W ater traps should be avoid-
ed. A ssem blies should be con-
structed w ith the open side
dow nw ards. (Figure XI.7)
•W eld discontinuities shall, also
w ith regard to other issues like
stress, fatigue etc., be strictly
avoided. (Figure XI.8)
•M aterials having different elec-
trochem ical potential have to be
separated from each other by
coatings or insulating m aterials.
2.2.5. Filiform corrosion
Filiform corrosion (also know n as
under-film corrosion) occurs
under paint or enam el layers. It
depends m ostly on environm en-
tal conditions and the quality of
the surface treatm ent prior to
painting. The corrosion filam ents
U nsuitable solutions
Better solutions
Run of
Run of
FIGURE XI.7
®
W atertight seal
FIGURE XI.6
W eld discontinuities
FIGURE XI.8
®
®
have a w orm -like appearance
and are readily visible. Filiform
corrosion does not attack the
m etal surface, but affects the
surface appearance.
The m ode of corrosion is quite
sim ilar to pitting w ith the front of
the attack being supported by
m oisture w hich penetrates the
surface layer and leads to oxygen
concentrated areas and by thus
acting as an anode. Filiform corro-
sion is m ainly an aesthetic effect,
but could lead in certain construc-
tion parts to delam inating of the
surface layer system .
To prevent this type of corrosion it
is of vital im portance to follow the
instructions of the paint supplier,
especially w ith regard to a proper
surface treatm ent under the use
of a suitable prim er system .
150
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X I CORROSI ON 150 | 151
2.2.6. 5000 series alloys
and elevated temperatures
W hen held for long periods at
elevated tem peratures (betw een
65°C and 200°C ), alum inium -
m agnesium alloys containing
m ore than 3% of m agnesium
undergo m etallurgical changes
that can lead to intergranular
corrosion if the tw o conditions
below are both satisfied:
•Precipitation of a continuous
bead of A l
8
M g
5
interm etallic
com pounds occurs along the
grain boundaries (sensitization).
These A l
8
M g
5
precipitations are
anodic to the bulk m aterial.
•Presence of an aggressive
m edium , e.g. a saline solution on
the bare surface of the m aterial.
This phenom enon has been studied
m any tim es w ith a view to gauging
the influence of the follow ing
param eters for sensitization:
•The m agnesium content and the
production process largely deter-
m ine the kinetics of sensitization of
5000 series m aterial. Proper routes
to m inim ize susceptibility are w ell
established at suppliers.
•M anufacturing processes like
form ing and therm al joining
(w elding) m ight reduce resistance
of final product to sensitization.
•The therm al load (i.e. tem per-
ature m ultiplied by tim e of expo-
sure) is m ore im portant than the
tem perature alone. For exam ple,
if 65°C is often given as a lim it in
catalogues or m anuals, it takes
tw o years to sensitize a 5086
alloy at that tem perature, w hile
at 100°C , several m onths are
necessary. The fastest sensitiza-
tions are generally observed
betw een 130°C and 200°C .
But even if a m aterial is sensi-
tized, corrosion w ill only happen
in aggressive environm ents, i.e.
w hen a corrosive electrolyte gets
in contact w ith the m etal surface.
Experience has confirm ed this.
There are road tankers for heavy
fuel oil, w hich have seen 20 years
and m ore of service, running 8 to
10 hours a day, w hich is at least
50,000 hours of cum ulative
operation at 65-70°C .
A s a general guideline, the use of
alloys w ith a m axim um of 3% of
m agnesium is strongly recom -
m ended w here exposure for long
periods to tem peratures in excess
of about 75°C occurs. W hen the
use of 5000 alloys w ith higher
M g content is desired, consulta-
tion w ith the m aterial producer is
recom m ended and their applica-
bility m ust be evaluated in detail,
taking into account the therm al
exposure of the part during its
total lifetim e.
2.2.7. Other forms of corrosion
O ther form s of corrosion do exist,
but the alloys and tem pers m ost
currently used in com m ercial
vehicles are not prone to these
types of corrosion.
2.3. Fur t her r ef er ences
•Corrosion of aluminium,
C . Vargel, ed. Elsevier
•w w w .corrosion-alum inium .com
151
EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION
152
1. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
2. THE NATURE OF STAINS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 154
3. THE CHOICE OF DETERGENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
4. APPLICATION OF THE DETERGENT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 155
CHAPTER XI I
CLEANING OF ALUMINIUM
COMMERCIAL VEHICLES
153
EUROPEAN ALUMINIUM ASSOCIATION
Regular cleaning of a com m ercial
vehicle is a prerequisite to ensure
a long lifetim e. A ny kind of dirt is
rem oved, the optical attractive-
ness is kept and critical parts like
w heels, axles, brakes and
hydraulic system s can be better
optically controlled. C orrosion is
prevented and dam ages due to
m echanical friction betw een
m oving parts can be avoided.
In case of tank trailers, there are
often strict legal regulations con-
cerning the transport of food-
stuff or there are other regula-
tions for strict cleaning w hen dif-
ferent chem icals are transported
w hich m ight interfere w ith the
goods transported before. In
som e cases, alum inium cannot
be used as a construction m ateri-
al due to the cleaning instruc-
tions, w hich specify the use of
strong aciduous or alkaline
chem icals
In general, cleaning of an alu-
m inium vehicle is not different
from cleaning any other vehicle.
It can be done on autom atic
w ashing lines as w ell as m anual-
ly w ith the use of high pressure
spray guns, brushes and cloths.
1. Introducti on
Commerci al vehi cl e cl eani ng st at i on (Int erservi ce Arras)
154
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X I I CLEA N I N G OF A LU M I N I U M COM M ERCI A L V EHI CLES 154 | 155
Stains on com m ercial vehicles
m ay have the follow ing origins:
•Road caused: dirt, salts, m ud,
w ater splash, tyre w ear
•Fuel caused: diesel exhaust, soot
•Load caused: cem ent, asphalt,
chalk, residues of agricultural
products etc.
•Environm entally caused: effects
of air pollution, dust
A ll these elem ents, in connection
w ith hum idity, can lead to local
corrosion and fading or destruc-
tion of the paint layer.
In this respect, residues of previ-
ously transported goods prior to
a new load m ight also be seen as
contam ination and require inten-
sive cleaning.
2. The nature
of stai ns
The detergent used for cleaning an
alum inium vehicle m ust be com -
patible w ith alum inium , m eans it
m ust not be too aggressive.
In general, a detergent has to:
•H ave a strong effect on all
kinds of dirt
The cleaning of a vehicle should
not take place in direct sunlight.
Each detergent should be tested
on a raw alum inium surface prior
to first use.
The detergent can be used either
in autom atic w ashing lines or can
be applied m anually w ith the use
of high pressure spray guns,
brushes, cloths etc. Its m ain
cleaning effects are:
•C hem ical
Som e elem ents of the detergent
dissolve the dirt or m ineral salts
w ithout attacking the surface
3. The choi ce
of detergent
•A llow an efficient rem oval of
aggressive dirt
•C reate a bright visual appear-
ance of the surface
•Build up a protective film on
top of the paint
•Be in com pliance w ith specific
regulations
•Be biologically degradable
•Be harm less to the user
D etergents are a com plex m ix-
ture of up to 20 ingredients to
enable diverse functions at the
sam e tim e: degreasing, slight
etching, w ashing, conserving etc.
4. Application
of the detergent
•Physical
Stains are rem oved by decreasing
the surface tension. Therefore deter-
gents contain w etting elem ents
•M echanical
Stains are rem oved by spraying
w ith pressurised detergent or by
abrasion w hen using brushes
•Tem perature
H igher tem peratures, or even
w ater steam , increase the clean-
ing effect by increasing the speed
of the chem ical reaction betw een
the detergent and the stain.
Spraying should be done from
bottom to top of the vehicle to
prevent streaking. The residence
tim e should be sufficient to dis-
solve the stains. The detergent
should not dry on the vehicle sur-
face and w ashing should be fol-
low ed by intensive rinsing w ith
de-ionized w ater.
155
EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION EUROPEAN ALUMINIUM ASSOCIATION
156
1. FOREWORD . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 158
2. EXECUTION OF REPAIR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
3. REPAIR OF ALUMINIUM CHASSIS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
4. MIG AND TIG WELD REPAIRS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4. 1. Choice of alloy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4. 2. Preparations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 160
4. 3. Welding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161
CHAPTER XI I I
REPAIR OF ALUMINIUM
COMMERCIAL VEHICLES
157
EUROPEAN ALUMINIUM ASSOCIATION
1. Foreword
Repair of com m ercial vehicles
should be done w ith the sam e
care as new construction. In
general, all rules, m aterials and
m ethods used for new construc-
tion should also be applied for
repair causes.
Repair is a case-to-case decision,
w hether sm all dam aged parts
can be repaired w ithout dis-
assem bling the structure or
w hether dam aged com ponents
(plates, extrusions) m ust be cut
out and replaced com pletely.
In any case, dam ages should
never just be “over-w elded”.
This m ethod does not reflect a
reasonable w ay of repair. A ny
parts, w hich have been cut out
due to dam ages, m ust alw ays be
replaced w ith the sam e type of
alloy as originally used. This has
to be applied to ensure a safe
and constant stress deviation
across the vehicle and to prevent
a w eakening of the construction.
It has to be taken into consider-
ation, that especially tankers or
silo trailers are regarded as pres-
surized vessels under the
European Pressure Vessel
Regulation 97/23/EU . This
requires additional testing
m ethods for repairs and supervi-
sion by certified supervision
bodies (like TÜ V).
Repair should therefore be car-
ried out by the m anufacturer of
the original vehicle or in certi-
fied repair w orkshops: qualified
w elders, w orking m ethods
according to state-of-the-art
technologies, suitable w ork
organisation, etc. are necessary.
Insi de vi ew of a repai red al umi ni um t ank (Fel dbi nder)
158
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER X I I I REPA I R OF A LU M I N I U M COM M ERCI A L V EHI CLES 158 | 159
A sophisticated repair of an alu-
m inium com m ercial vehicle
should be done according to the
follow ing procedures:
•Identification of the dam age
- H ow m uch m etal has been
destructed?
- A ny further dam ages w hich
could not be seen during first
inspection?
•C ut out of dam aged com po-
nents
•Identification of originally
used m aterial specification
•O rder of replacem ent m aterial
according to detected specification
•O rder of suitable w elding
filler w ire (according to norm s or
specific regulations)
•Pre-cut of replacem ent part
under consideration of the ther-
m al shrinking during w elding
•Pre-form replacem ent m ateri-
al if necessary
•Rem oval of original coating in
the repair zone
•Fixing of the replacem ent part
to the vehicle; if necessary addi-
tional form ing to the vehicle
contour to prevent too m uch
stress during w elding
•Joining of the replacem ent
part to the vehicle structure by
suitable w elding m ethods.
•Visual control of the w eld quality
•If necessary or m andatory
(pressure vessels), then non-
destructive testing (ultrasonic, x-
ray) of the w eld seam
•G rinding or flattening of the
w eld seam
•Repair of the coating
•Final control; it m ight be
required to let all steps of repair
be checked by a supervisory
organisation.
2. Executi on of repai r 3. Repai r
of al umi ni um
chassi s
The case of alum inium chassis
deserves a particular attention,
as a non-professional repair m ay
lead to a deterioration of both
the static capacity and fatigue
strength.
To avoid this kind of problem s,
please read C hapter VI, section
8, dedicated to fatigue.
Beginning w ith fatigue theory,
that chapter also illustrates how
good practices for perforating
and w elding can secure long
lifespan to vehicle.
Out si de vi ew of a repai red al umi ni um t ank (Fel dbi nder)
159
EUROPEAN ALUMINIUM ASSOCIATION
A road vehicle can sustain dam -
age and w ill need to be repaired.
Repairing a com m ercial vehicle
m ade from alum inium alloys is
no m ore difficult than repairing a
steel vehicle, but should be done
according to a strict procedure in
a properly equipped w orkshop
by skilled operatives under the
supervision of an official body
and/or classification society if the
vehicle's duty calls for this.
N o repair w ork should com -
m ence w ithout-know ing the
type of freight (liquid, pow der
etc.) w hich the vehicle has been
used to carry and before taking
the appropriate safety precau-
tions: cleaning, degassing, w ith
explosim eter checks, dust
rem oval etc. as necessary.
4.1. Choi ce of al l oy
The alloy of the sem i-finished
products used for the repair
w ork m ust be the sam e as (or
com patible w ith) the original
alloys as indicated in the m anu-
facturer's m anual.
4.2. Pr epar at i ons
This is the m ost im portant phase
as it w ill determ ine the quality
and strength of the repair:
•for cutting out, preference
should be given to the plasm a
torch or a carbide cutting w heel
rather than a high speed steel
(H SS) w heel or abrasive w heels
that m ight introduce inclusions
into the w eld seam ,
•very carefully grind the area to
be w elded to rem ove all traces of
paint and various residues,
•carefully degrease w ith suit-
able agent
4. MIG and TIG wel d repai rs
Wel di ng of si l o body (Fel dbi nder)
160
ALUMINIUM IN COMMERCIAL VEHICULES CHA PTER V I I I WELDI N G 160 | 161
4.3. Wel di ng
The rules for repairing are basi-
cally as described in C hapter VII
for form ing and as described in
this chapter for w elding. W hen
carrying out repairs it is essential
to:
•hold the com ponents, e.g.
tank, chassis etc., securely in
their relative positions. C lam ps
should be adjusted to allow
expansion how ever, as too m uch
restriction could aggravate the
adverse effects of contraction. It
is also useful to m ark areas of the
structure likely to suffer m axi-
m um stress, referring to the
m anufacturer's design calcula-
tions if these are available,
•support built-up parts to con-
trol clearances,
•pay particular attention to the
w eld direction. The purpose of
this is to lim it deform ation and
m inim ize the risk of hot cracking.
Volum e contraction in the w eld
bead is approxim ately 6 %
betw een the fluid state and the
solid state at am bient tem pera-
ture. It is this phenom enon
w hich causes the risk of cracking,
•change the path of w elds in
order to avoid going back over an
original w eld (Figure VIII.7),
•perform any necessary tests, e.g.
radiography, dye penetration etc.,
•chose the right w elding
process (TIG or M IG ). TIG w eld-
ing is preferable for m inor repairs
w here access from behind is not
possible as it is easier to use and
allow s better penetration control
than M IG w elding.
C om pact TIG w elding m achines
w eighing less than 20 kg are
now available on the m arket
capable of delivering a w elding
current of around 160 A . These
m achines are easy to carry and
are ideal for sm all, localized
repairs.
For m inor repairs such as a
breach in the skin of a tank, the
patch m ust be perfectly m atched
to the shape of the breach but
should be slightly enlarged by
ham m ering to com pensate for
contraction follow ing w elding.
W ithout this precaution the
residual stress m ight w ell cause
system atic cracking. This phe-
nom enon is m ore pronounced
the sm aller the patch.
W ELD REPA IR
FIGURE VIII.4
®
N ew w eld
161
ACKNOWLEDGEM ENTS
Mai n wri ters: Jürg Zehnder, Rei nhard Pri tzl aff , Stei nar Lundberg, Bernard Gi l mont.
Project team: Asmund Brol i , Roal d Pedersen, Benoî t Lancrenon, Mi chel e Tri bol di ,
Di etri ch Wi eser, Ral f Bal duck, Kl aus Vi eregge.
Sponsori ng compani es: Al can Engi neered Products, Al coa Europe, Al eri s Europe, AMAG,
El val , Hydro Al umi ni um, Metra, Novel i s, Sapa
The project team i s parti cul arl y gratef ul to Al can Engi neered Products f or havi ng
authori zed to use some texts, tabl es and f i gures comi ng f rom the f ol l owi ng
publ i cati ons:
• Al umi ni um i n Commerci al Vehi cl es, Pechi ney-Rhenal u
• Al umi ni um and the Sea, Al can Aerospace, Transportati on and Industry
PHOTO AND TABLE CREDI TS
Document produced by
European A lum inium A ssociation A ISBL
A venue de Broqueville, 12
BE - 1150 Brussels - Belgium
Telephone: +32 2 775 63 40
Fax: +32 2 775 63 43
w w w .alum inium .org
U nder the D irection of Bernard G ilm ont
D esigned: M arc H ernu, Plage
C oordination: Pierre Jouhaud, PLJ édition-com m unication
1 Benalu Benalu
4 M enci EAA library
6, 8 Airbus Airbus
9 Hydro Alum inium Hydro Alum inium
9 Babcock Babcock
10 Alstom , SNCF Alstom , SNCF
11 M ercedes
11 Hydro Alum inium Hydro Alum inium
12 Alum inium -Verlag Alum inium -Verlag
12 Alusuisse Alcan Engineered Products
12 Trailor Trailor
16 Benalu Benalu
17 Tang Fahrzeugbau G m bH Tang Fahrzeugbau G m bH
19 All Am erican M arine All Am erican M arine
20, 36 Stas Stas, IRTE
21 Alcan, Alcoa, Brabant Alucast Alcan, Alcoa, Bernard G ilm ont
23 Alcan Engineered Products Alcan Engineered Products
24 G alloo Recycling Bernard G ilm ont
25 ATM , PVC Transports Patrick Van Crom brugghe
26 M enci Bernard G ilm ont
26 Alcoa W heel Products Europe Alcoa W heel Products Europe
27 Benalu Benalu
28 Pezzaioli Pezzaioli
30 Alcoa Europe Alcoa Europe
31 Stas Stas
32 Benalu Benalu
33 Leciñena Leciñena
34 M enci M enci
37 Schrader Schrader
40, 43 Alcan Engineered Products Alcan Engineered Products
44, 45, 47 Various alum inium plants EAA library
48 M enci Bernard G ilm ont
48 Alcoa Europe Alcoa Europe
54 Brabant Alucast Bernard G ilm ont
75 Alcoa Europe Alcoa Europe
76, 81 Benalu Benalu
82 Alum inium -Verlag Alum inium -Verlag
86 Schrader Schrader
87 Stas Stas
88 Schm itz Schm itz
89 M enci M enci
90, 105 König Ursula Berndsen
95 SAG Alutech SAG Alutech
97, 98, 99 Benalu Bernard G ilm ont
100 Sapa Sapa
108 Stas Stas
110 SAG Alutech SAG Alutech
112 M enci Bernard G ilm ont
114 Sachsenring Ursula Berndsen
119 Alcan Engineered Products Alcan Engineered Products
120 Sapa Sapa
121 Hydro Alum inium Hydro Alum inium
122 Schm itz Schm itz
128, 132 Alcan Engineered Products Bernard G ilm ont
135 Alcan Engineered Products Alcan Rhenalu Issoire
138 Trailor Trailor
140 LAG LAG
140 Benalu Benalu
142 LAG LAG
152, 155 Interservice, Arras Christian Vargel
156, 158, 159, 162 Feldbinder Feldbinder
Page Company or brand Photographer or source Page Company or brand Photographer or source
162

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