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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Unit 1 Wood uses for manufacturing industry
Introduction
Ethiopia possesses a big range of woody species amongst its luxuriant flora. To select the best wood for a particular purposes calls for an accurate knowledge of the qualities required and reliable information as to the woods possessing those qualities. The important technical features usually concerned in this selection are: (1) anatomical structure, (2) shape & size of the trees, (3) specific gravity, (4) strength, (5) hardness, (6) flexibility, (7) elasticity, (8) toughness, (9) adaptability or otherwise to seasoning, (10) natural durability and adaptability to preservative treatment, (11) color, grain, figure and similar characteristics,(12) freedom from defects, (13)adaptability to working with tools and on machines. In the choice of wood for a particular purpose, laboratory tests are necessary for ascertaining the desired properties and characteristics, but its suitability is finally decided only after actual trial. The basic physical and mechanical properties are not possessed in an equal degree by all woods; in fact, there is a very considerable variation among timbers both in appearance and their properties, particularly as regards weight, hardness, strength, degree of shrinkage, easy of working, ability to hold nails and screws, and reaction to pulping agents. Equally notable are the chemical and anatomical differences. The choice of species for any particular use is decided by combined presence of desired properties and characteristics. It should be realized that an appreciable equalization of the properties of wood can be achieved by proper design and treatment.
1.1 Aircraft timber industry
Requirement of timber
Timber is required for the following four purposes: a. b. c. d. For general constructional work and main members. For the high quality plywood used for covering purposes. For propeller manufacture. For linings and for sandwich construction between two plywood skins.
Qualities of timber required
The timber has to be sound, free from knots, straight-grained and light in weight, should possess high strength/weight ratio. 1
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) The growth should be uniform, only pieces with 3 to 6 growth rings/cm being accepted. For linings and sandwich construction, lightness in weight coupled with minimum required strength, resilience and sound-proofing properties are chief consideration. In the international market, a weight of up to 224kg/cu m is considered to be satisfactory.
Timbers suitable for aircraft construction
a) For main members- Fir (Abies pindrow) and spruce (Picea smithiana) alone come up to international standard. b) Aircraft quality plywood- Indian birch and maple are suitable. c) For propeller-Timber suitable for propeller are padauk, aini (Artocarpus hirsuta),chickrassy(Chukrasia tabularis), champ(Michelia champaca). More advanced types of propeller are made wholly or purely of compregnated wood (resin-impegnated laminated and compressed wood). d) Materials for linings and for sandwich construction between two plywood skins- Balsa (Ochroma pyramidalis) is the world¶s best timber for this purpose. Pieces with a density of 128-224kg/cu m are accepted commercially. Suitable substitute of balsa are Cryptomeria japonica (density about 256 kg/cu m),Erythrina suberosa( density 240 kg/cu m) and Sterculia villosa(density about 272kg/cu m) Finally, it should not be forgotten that aeroplanes are being constructed very largely of metal nowadays and that, though the demand for wood will continue for certain parts, the use of wood in aircraft construction is not as much as it once was.
1.2 Boxes, Crates and Packing Cases
In Ethiopia, as elsewhere, packing is one of the important end uses of wood. Wooden packaging has always been preferred for fresh fruits, machinery, aircraft parts, precision instruments etc. Manufacturers of shoes, matches, soaps, chemicals and toilet preparations, pencils, articles of stationery, paints and varnishes etc require large quantities of packing cases. Paper mills and coffee-packing industry also require large quantities of wood for this purpose.
Qualities required in packing case wood
Packaging serves three principal purposes, viz., protection, ease of handling and advertisement. The primary requirements of a wood for use in packing cases are lightness in weight combined with required strength for purpose, and good nail and screw holding power. Timbers weighing about 350-420 kg/cu m in air-dry condition are suitable for packing cases. Timber for packing cases should preferably be of light color so that it may carry stencil marks well, this having an advertising value in trade: the trade would prefer a goodlooking, white good. The timber for ammunition boxes should have good retention of shape and size combined with required strength, particularly for small arms and ammunition.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) Timber for packing cases should be straight grain and free from insect attack, decay, objectionable knots, splits and warping. Timber for cheap type of packing cases should be seasoned to moisture content not exceeding 18%. Timber for better quality of packing cases should be thoroughly seasoned to moisture content of 12-18%, depending on the locality of use and manufacturer.
Classification of packing case timber
Timbers are classified as follows from the point of view of their suitability for packing cases intended for varying loads: Class Density of timber
Class I Class II Class III Class IV
640 kg/cu m and above 481-639 kg/cu m 400-480 kg/cu m less than 400 kg/cu m
The suitability of different classes of timbers according to the loads to be handled is roughly as follows. Types of load Class of timber recommended
Very easy load or up to 320 kg cu m Easy load or 321-640 kg/cu m Average load or 641-1280 kg/cu m Difficult load or more than 1281 kg/cu m
III III & II II II & I
Recommended Ethiopian timber: Assignment- Classify Ethiopian timber based on their density.
1.3 Match box & splints
The match box industry is one of the most important timber-using industries in world. The annual production and consumption run to many trillions of matches requiring several millions cu m of wood. 3
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) A match is a piece of inflammable material generally made of wood, but sometimes also of cardboard or other material and provided with a tip consisting of a mixture of chemicals and other substances that may be ignite by friction. It is the most widely used agency yet invented for obtaining fire. In Ethiopia, matches are primarily made of wood only. Match boxes are also of different types: all wood, all cardboard, or a mixture of both. Match boxes are of µfull size¶, µthree quarter size¶, or µhalf size¶. Full size¶, and µhalf size¶ are common, and measure, respectively, 7.30 cmx3.73 cmx1.83 cm, and 4.60 cm x 3.29cm x 1.55cm, including boxes and splints.
Quality of a match wood
The essential qualities required in match wood are: straightness of grain, good strength and toughness combined with lightness, good white color, freedom from knots and cracks, and capacity to absorb paraffin readily and hold the head firmly. The log should be round and easily peelable on the veneering lathe, and the wood should be easily available.
Suitable wood for match industry
Bombax ceiba, Dysoxylon malabaricum, Endospermum melaceense, Salmalica insignis,Spondias pinnata. Efforts have been made from time to time to manufacture splints and boxes from bamboos, reeds and grasses, but the results have seldom been satisfactory.
1.4 Pulp wood
Wood is an important raw material for the production of pulp, and is at present the one most widely used in the world for paper pulp. While woods of coniferous species are more widely used than those of broadleaved species, the demand for paper and pulp products is so great that the woods of broadleaved trees are being employed in ever-increasing amounts. Woods of various coniferous and broadleaved species are suitable for pulping. Some suitable species are listed below: Fir (Abies pindrow) ,Green wattle (Acacia decurrens), Siris (Albizia chinensis) , Salai (Boswellia serrata) , Suji (Cryptomeria japonica), Blue gum (Eucalyptus globulus ), Spruce (Picea smithiana), Chir (Pinus roxburghii) ,Poplar (Populus ciliata)
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Unit 2 Wood uses for transportation industry
2.1 Carts and Carriage
The various parts of a cart or carriage are subjected to different kinds of stresses and strains, and require different qualities of wood for real efficiency. The main parts of a cart or carriage are: i) the framework ii) the axle, iii) the wheals and iv) the shafts or poles.
Framework
A strong wood which is not too heavy is preferable for this purpose (Gmelina arborea) is an excellent timber for light carts. Sissoo (Delbergia sissoo) is one of the best woods in the market for the framework of carriages
Axle
A very hard and tough wood is essential for this purpose. Such timbers as babul (Acacia nilotica, axel wood (Anogeissus latifolia) 5
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Wheels
Wheels are composed of three main parts: the nave or hub, the spokes, and the felloes. Each of these parts requires certain distinct quality in the wood used. Hub ± the wood for this purpose must be straight grained, strong and elastic. It should also be free from defect and not liable to warp or sharing, the later fault resulting in the spokes becoming lose in the mortise of the hub and felloes. The best woods for the purpose are rose wood (Delbergia latifolia) sissoo, dhaman(Grewia tiliaefolia), and bijasal. Felloes-These are subjected too much crushing and alternation all of wetting and drying, and must be hard, strong, elastic and durable. To make a really strong wheel, naturally curved or bent timber is the best, so that the grain of the wood follows the line of the circumference of the wheel as nearly as possible. The best woods for the felloes are babul, rosewood, dhaman and bijasal.
Shafts or poles
Woods for this purpose should be straight grained, tough, elastic and very strong. The best woods are Grewia spp, Anogeissus spp., and similar very strong wood. Pterocarpus dalbergiodes, and Shorea robusta are of the type likely to be most suiable. Bamboos are very commonly used for buggy shafts, being light and strong.
2.2Railway carriages and wagons
The manufacture of railway carriages and wagons is an important timber utilizing industry in the world. Although frames of carriages and wagons are now a days invariably made of steel, wooden bodes are also in use. The proportion of wood used is gradually decrees as the railway are bringing in to use carriages with steel shell in which the use of wood is restrict to interior fitting.
Qualities required in the wood
Wood used for railway carriage building should generally be strong but not very heavy. As explained below, other properties have also to be taken in to account with reference to the specific parts of the carriage for which the wood is to be used. The timbers required for carriage and wagon building fall in to the following for distinct class: a) Fore main members of passenger coaches, such as bottom sides, pillars, can¶t rears and cross bars: a generally strong and very steady wood is required for this component. For along time, only Burma teak (Tectona grandis) was being used, but now Indian teak and padauk (Petrocarpus dalbergioides) have been accepted as equally good substitute. b) For interior fittings such as boarding, paneling, ceiling , partitions seats, etc« most furniture class woods can be used for this components, the main requirements being moderate strength, reasonably good retention of shape and size in service, and good figure,grain and color. c) For foot -boards± hard and strong timbers are needed for this use
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) d) For floor boards : hard and strong timbers are needed to with stand the continual wearing out and indentation stresses to which floor boards are subjected
2.3 Railway sleepers
The chief functions of sleepers are to support the rails, distribute the load from the rail to the ballast, and maintain a gauge. Wooden sleeper fulfils all this requirements very satisfactorily. The average annual requirement of sleepers of all categories is assessed to be at about 10 million. As supply of wooden sleepers is limited, the railways are trying to effect a gradual reduction in the use of wood for sleepers and are going for sleepers of cast iron, steel and pre-stressed concrete.
Qualities required in the wood
The wood for sleepers should have strength, including transverse strength to resist breakage by centre, binding and compressive strength to resist the pressure. It should be hard to resist rail abrasion. It should have spike holding power to resist undue spike loosening and good seasoning property without excessive splitting, cracking, warping etc. For all treated sleepers, the timber must be amenable to treatment with coal tar creosote or other preservative at reasonable cost.
Suitable timbers
1. Untreated sleepers- Shorea robusta, Cedrus deodara, Xylia xylocarpa, Lagerstromia purviflora, Ptreocarpus marsupium. 2. Treated sleepers- Shorea robusta, Cedrus deodara, Abies pindrow, ,Albizia lebbeck, , Anogeissus latifolia, Pinus roxburghii, Pinus wallichiana, lagerstromea lanceolata.
2.4 Road paving blocks
The use of wood for paving streets is said to have originated in Russia. It was later introduced into England, America and elsewhere. The method consists in embedding small blocks of wood in bituminous compounds. Even in the modern days of reinforced concrete and other compositions, wood has certain qualifications as a street-surfacing material which none of the other materials so far discovered for the purpose possesses. In the first place, wooden paving-blocks compare favorably in cost with other surfacing materials and offer better resistance to the skidding of motor cars than concrete or composition surfaces. They also compare very favorable in durability and wear and tear with other roadsurfacing materials. Above all, they are silent under heavy traffic, which in street fronted with offices, shops, hospitals etc is an important consideration.
Characteristic required in wood
The chief requisites of good wooden paving-block are durability, resistance to wear and tear, resilience, and non- liability to absorb water excessively. The texture should also be even, as otherwise the blocks wear unevenly. 7
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) The general rule is that the paving- blokes should be laid with the cross-section surfaces at top and bottom and not on the sides. This is necessary to ensure even wear and tear, as the end-surface of wood wears far more evenly than the tangential or radial surfaces.
Wood recommended and in use
Irul (xylia xylocarpa), Tectona grandis, Acaia catechu, Hopea parviflora.
2.5 Ship and boat building
In former times, before the advent of iron and steel, the demand for ship building timbers was one of the heaviest on the timber industry. The demand is even now very large, but the purposes for which the timber is required have changed. Nowadays wood is confined chiefly to deck planking and interior fitments. This, of course, is only natural when it is remembered that iron ships are stronger and more able to resist the buffetings, of heavy seas, are more durable and easier to repair, and can be built to sizes far beyond the possibilities of wood. The shipping of today is many times what it was years ago, and the demand for deck planking, cabin fitments and interior decorative woods is greater than ever.
Requisite properties of timber
Timber for ship building should be strong, elastic and durable and free from defects to stand the enormous strains. Teak(Tactona grandis) is the best wood ship building timber in the world not only because of durability, strength,
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Unit 3 Wood uses for sports good industry
Sports goods include a large number of articles, such as hockey sticks, cricket bats, tennis and badminton rackets, golf clubs, billiard cues, skies, cricket stumps and bails, fishing rods, etc. The requirements of wood for sports goods are very exacting. Timbers with a combination of certain specific properties are needed and the choice of species is limited.
Requisite properties of timber
The requirements of wood are very exacting. It must be light with high strength/wt. ratio, pliable, tough, shock resistance, easy to work, capable of taking a good polish and preferably light in colour. In Europe and America, ash (Fraxinus spp.) is commonly used for the purpose, and in India mulberry became the standard sports goods timber as a substitute for imported ash. Different qualities are however, required for different articles of sport. The different categories of sports goods and the woods used or found suitable are discussed below.
3.1 Billiards cues
Timber for this purpose has to be right weight and must have a straight grain. It should be white in colour or nearly so, free from knots and other defects. Recommended Species: Ebony (Diospyros melanoxylon), Polyanthia fragrans, Sageraea elliptica, have been tried and found suitable. 9
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
3.2 Bows and arrows
Yew (Taxus baccata) is an excellent bow wood. It is very strong, tough and an elastic wood. Other woods used for this purpose are Grewia tiliefolia, Pterocarpus marsupium, Acacia catechu. For arrows good strong wood which will not warp is required. Coniferous are sometimes used but are too light for the purpose. Delbergia sisoo, Pterocarpus marsupium are suitable. Reeds and bamboos are also commonly used for arrows.
3.3 Cricket bats, stumps and bails
The timber for cricket bats should be light in colour and light in weight but reasonably strong. It should be able to take the shock of repeated striking of the ball with great force. The best and the only wood used for bats is willow (Salix spp.). The best cricket bats are made of the English cricket bat willow( Salix alba var Caerulea) of the U.K.. Cheap quality bats can be made from Melia azadarach, populous Spp. Mulberry( Morus alba) is most commonly used for stumps and bails but other woods like Celtis australis, Polyalthia fragnus are also suitable.
3.4 Fishing rods
For cheap rods, bamboos are chiefly used, Arundinaria falcate being amongst the most popular. Wood most commonly used for superior quality fishing rod is green heart (Ocotea rodioei), a South American species. Some other species like Terminalia manii and Sageraea elliptica have also been found suitable.
3.5 Golf clubs
Wooden golf clubs are usually made of South American hickory (Carya spp). Ash is also used for golf club shafts. Golf club heads are made of persimmon (Diospyros virginiana). Terminalia manii, Acacia nilotica, Chloroxylon swietenia, Tamarandus indica, Mesua ferrea have been used with success for heads of wooden clubs.
3.6 Hockey sticks
The timber for this purpose should be reasonably light but strong, particularly in its shock resistance. It should be amenable to steam bending in thick sections. Ash is commonly used in western countries. Mulberry (Morus alba) has been found suitable for hockey sticks. Amongest other substitutes Celtis australis also makes a satisfactory hockey sticks.
3.7 Tennis, badminton and squash rackets
All tennis, badminton and squash rackets of built-up construction obtained by bending and gluing together thin veneers of wood.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) Straight grained, long fibered wood with good shock resistance is essential for rackets. Ash (Fraxinus spp), maple (Acer spp.), are commonly used in the western countries. Mulberry is also found excellent for the purpose. Other suitable woods are lagerstroemia hypoleuca and lagerstroemia lanceolata.
3.8 Skies
Toughness, flexibility, even texture, and straight grain are the essential qualities of a good ski wood. Ash and hickory are used in Western countries. Delbergia sisoo, Morus alba and Axel wood (Anogeissus latifolia ) have been found suitable for the purpose.
Unit 4 Wood uses for agricultural implements, post & poles
4.1 Fence posts
In many parts of Ethiopia, a short pole cut from a young or small tree is used as a fence post, usually in its natural round shape and often with the bark on. Such a post contains a large percentage of sapwood, and as the sapwood of all species, including that of sal (Shorea robusta), teak (Tectona grandis), deodar (Cedrus deodara) and other trees with durable heartwood, is very liable to attack by fungus and insects, and as the bark on a dead stem is sure to attract wood-boring insects, a post of this type is not really serviceable. If the bark and sapwood are chipped off before use, the result will be more satisfactory, and such posts will give good service, at any rate for temporary
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
purposes, if the species used has reasonably durable heartwood. In most localities in Ethiopia, owing to the prevalence of termites, fungi and borers, the heartwood of a fairly durable species should be used for fence posts, or the posts should be treated with a good preservative. It is usually sufficient to' treat only the lower portion of the post, as the portion above ground is often not subject to adverse influences, but the treatment should extend up to a quarter of a meter or so above the groundlevel part of the post. A simple butt treatment in an open tank or barrel is usually adequate; but, should the post be required to give service for '1 number of years, a thorough treatment in a pressure cylinder is necessary. A very useful and moderately durable post can be obtained by charring its surface over a fire before planting it in the ground.
Qualities required in the wood
Reasonable strength and durability are the only qualities required.
Woods in use
The following timbers are likely to give good service: babul, khair (Acacia catechu), deodar, hopea (Hopea parviflora), pterocarpus spp, Sal, teak and irul (Xylia xylocarpa).
4.2 Fresh w ater piles
As marine borers are confined to brackish or saline water, constructional work in freshwater is not subject to attack by these pests, and the selection of timbers for this type of work is thereby greatly simplified. The type of structure for which the timber is required, however, plays an important part in selecting the best wood for the purpose. If the structure is to be completely Immersed in freshwater at all times, selection is easy, as submerged wood is protected from attack by insects and ordinary fungi, and several woods which are considered as most perishable when exposed to the air give good service indefinitely if kept under water. Good examples of this are salai (Boswellia serrata), Erythrina suberosa, mango (Mangifera indica), semul (Bombax ceiba) and bahera (Terminalia bellirica). All these woods are perishable timbers in ordinary circumstances, but if kept completely submerged under freshwater, they remain almost indefinitely in good condition. If, on the other hand, the structure is to be exposed to alternate wetting and drying, the situation is entirely changed, as conditions most favorable for the rapid development of wood destroying fungi are at once set up. Unfortunately, in such constructions as piers, jetties, bridge piles, well
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
curbs, sluice gates, and river-bank protection against erosion. Alternate wetting and drying is unavoidable, and unless preservative treatment is adopted, it is necessary to use only those timbers that are durable under these conditions. The choice is, therefore, restricted to such wood as babul, Artocarpus spp., deodar (Cedrus deodara), hopea (Hopea spp.), Lagerstroamia spp and teak (Tectona grandis). Of these, uriam and pyinma (Lagerstroemia hypoleuca) have been reported on as being exceptionally durable if kept wet.
4.3 P iles
Piles comprise the main upright members in bridge building, etc. They usually have the lower portion of their length sunk in the ground. This portion, and more especially that near the ground level on dry land, is very liable to at tack by termites and fungi. The portion of the pile below water level is not subject to attack from termites or fungi. Quality required in the Wood The essential qualities required in a good pile wood are great durability (the most important) and great strength and resistance to shearing, splitting and endcrushing, it must be capable of standing up to the continuous blows of the pile driver during the process of being driven into the ground. Woods in use Amongst the best of the woods for the purpose are: babul (Acacia nilotica ssp indica), khair (Acacia catechu), aini (Artocarpus hirsuta), deodar (Cedrus deodara),hopea (Hopea paroijiora), sal (Shorea robusta), teak (Tectona grandis) and irul (Xylia xyIocarpa).
4.4 Telegraph, telephone & electric poles
The scope of use of wood poles
There is an increasing demand for cheap types of supports for' overhead power and telecommunication lines. Owing to the prohibitive cost of tubular poles, various other types of supports such as concrete posts, used rails, and wood poles have been tried for this, purposes. Wood pole lines are considered to be the cheapest as regards initial cost as compared with all other types of supports. On account of their very elastic nature, wood poles are used both for shortspan low-voltage systems, and also to a limited extent for high- voltage transmission lines.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Essential and desirable properties of wooden poles It should be obtainable in good straight length. It should not split or crack excessively, and should have the required length. It should be free from sap rot, hollows, cross breaks and large holes all of which are categorized as a totally prohibited defects.
4.5 Tent poles and Tent pegs
Tent poles Tent poles are usually of bamboo, but it is not uncommon to see large tent poles made of wood; such poles can be either round or squared. A good strong wood is desirable, Common timbers in use are dhaman (Grewia tiliaefolia), sal and Teak (Tectona grandis). Tent pegs Tent pegs may vary in size from the small 15 cm pegs, used with very light tents, to the very large pegs '1 m long and 10 cm in diameter used with big marquees. These must be made of a hard, durable wood, which should also be tough enough to resist hammering. There is a big demand in the country for suitable woods for tent pegs of all descriptions. Many woods are suitable for this purpose. Among the best of these are babul (Acacia nilotica spp indica), sundri (Heritiera minor), sandan (Ougeinia oojeinensis), kusum , sal Tamarindus indica) . Other good tent-peg woods are sissoo (Dalbergia sissoo), dhaman (Grewia spp.) and irul (Xylia xylocarpa). The most common type of tent peg is a round peg cut from a branch or sapling, This type of peg is liable to crack, the wood being, more often than not, quite green. A more satisfactory peg can be sawn from a plank of seasoned wood to the size and shape required.
4.6 Agricultural implements
"Agricultural implements" is a comprehensive term with a wide application, but in common use it usually refers to such appliances as ploughs, harrows, rollers, and clod-crushers. In Ethiopia, these implements are, more often than not made entirely on wood, and the amount of timber used for their construction is quite considerable. Only the strongest, toughest and hardest woods are of any use for such world and the local wood which complies best with these essentials is the one usually employed. The following some woods are all used for agricultural implements of different kinds: Acacia nilotica, Acacia catechu, Axel wood, sissoo, oaks, sal, irul etc.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
I.
Unit 5- Wood uses for textile & jute mill accessories
II. III. IV. V. 5.1 Bobbins 5.2 Shuttles 5.3 Picker arms 5.4 Loom components
Sp"cin ill use .--1 IalJu 1 ! I! l'; '''rdj-nit I ..'1
. ' ; Lhe (;{)mmqnh" \Is·>d wood for most kinds of bobbins. For thinner"walled pirn~, rnaplr: (Acer spp.), birch (Betula spp.) wh;te cular (D)so.'..lulIl ma{abalicum), and mullilarn (FagfiTa budnmlfa) are p~elerred, bu~ these woods are in short suPUly ThcI'cfore, imported maple, birch and beech are still being used to some extent.
Species recommended.-Of Indian woods, maple, haldu, birch, white (1\1itrag)'t1a parvifolia) are recommended. (ii) .lute-mill bobbins
cedar, mullilam and kaim
Jute-mill bobbins are usually larger and thicker-walled in design, and the requirements as to finish are not always as exacting as in the case of cOHon-mill bobbins. Moreover,. introduction of 3-ply ends of wood construction and composite metal- and wood-desIgn has enabled the use of several cheap-grade secondary species. Species in use.-Mango (Mangifera indica) and silver oak (Greyillea robust a) are most commonly used, while haldu and kaim are also occasionally used. No imported timbers are used. Haldu Chaplash (Artoearpus chaplasha) Birch Toon (Toollo ciliata) Cll ickrassy (C/wkrasia tabularis) G?mari (Gmelina arborea) SilvFr oak Kal'ju J-fulnpte!ea intrg1'ljalia) Kw han ([1) menOdl(t)Ofl .:xce!sum) 1\1ango Ch?mp (.'vfiehelia eharnpcca) Bon,um (Phoebe spp.) (b) For slwlU\s Haldu Toon Chickrassy Silver oak ~rango Kaim Sppcie, ill /lSt'.-Babul './<I.(ia Ili!utir(l ssp irdie,!). axl(wood (Anog,issl<S latijoli.I), tht !.igh t-colfJlH cd s; p W lJcd e,f ~b, Ii) U)i.';,~t:Jrn~ IIdar'{'X);(lI~, ci!l<,!1,;,ln S:rcil ia tifi,;eJO.':.l'. ~ll.,d l.endi (Lagemru/'mia Ix/rvif!,ura) arc fi01\ being uscd to an inere, , extent. . A .lm,,' amount of imported hicko:y is howt:\,er still used. parti"'ula,"'~ for jttte·mlil pIckel.' arms. Lamina/cll-wood pi ekcr ;lrms madc of thc aoove limbers have recently been introduced and have been "ery fa ""ourably reported upon, Species recornmended.--Dhaman w"s found to be as good as' imported hickory in small·scale service trials
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
c<lrried out in eottor--miJls by the Forest Research Institute, Dehra Dun, whilc babul, Iendi, and sardan (Ougeinia oojeinensis) were favourably reported upon. Other suitable timber.s "me: axlewood, sissoo (DalbergiQ sissco), ebony (DiosRyros melanox)'lon), and laurd p:;;rmir.alia tumcnlosa), only the light-coloured Qutn' wood being used in the case of ebony. Properties essential or desircble,··- 'I he tin,ber she uld be straight-gl'aincd and fineand even-te...,,;:tured. It should turn well and should be smooth to finish. It sho ld not split when metal fastenings are inserted. It should be reasonably strong, but should have considerable resilience and resistance to splitting. It should have good wearing quality and sh uld wear smooth in prolcng(d friction against the loom-race pI,2te and yarn. The timber shodd preferably he of weight about 8:30 j,g/cu m (air dry). It should season wen without much degrade. Species in use.--Imported cornel, persimmon or horn bet-m (Carfinus spp.) is still preferred. Rosewood (Dalbergia latifolia) and the light-co loured sapwood of ebony (Diosp)'ros melano:<ylon) are indigenous timbers now being used to some extent. Compressed blocks with the sapwood of (DiospJToS melano:>:jlon) for the core arid laminated wood for the two sides have been introduced reclntly to a limited extent. Efforts are under way to introduce more extensive use (;f laminated and/or compre3sed wood. Species recommend, d,--'I h e ligh H .G lc ured sa p" (, c,d III DiGS!!) ros I/ulunox.)ivn . ,'as found to be thi; nearest to and a l'casona !')ly goed substitute for imported cornel for shuttles in service tests carried out in cotton-miils by the Forest Research Institute, Dehra Dun. The hIll tirr"bers 'Kharsll cak (Q].ereus semecarpifolia) and parrotia (Parrotia jaequemollliana) apI-car to be very promlsll g on the of their physical and mechanical properties. Other timbers worth tf) ing for the purpose are rosewood, gardeni.l .Gardenia latijc,fia), sandan. al':1 rnoh-I.;, ,S,hlt'bera swicteniaides). Laminated and/or co In pessed \\ ood has Lright prospects.
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Unit 1 Wood uses for manufacturing industry
Introduction
Ethiopia possesses a big range of woody species amongst its luxuriant flora. To select the best wood for a particular purposes calls for an accurate knowledge of the qualities required and reliable information as to the woods possessing those qualities. The important technical features usually concerned in this selection are: (1) anatomical structure, (2) shape & size of the trees, (3) specific gravity, (4) strength, (5) hardness, (6) flexibility, (7) elasticity, (8) toughness, (9) adaptability or otherwise to seasoning, (10) natural durability and adaptability to preservative treatment, (11) color, grain, figure and similar characteristics,(12) freedom from defects, (13)adaptability to working with tools and on machines. In the choice of wood for a particular purpose, laboratory tests are necessary for ascertaining the desired properties and characteristics, but its suitability is finally decided only after actual trial. The basic physical and mechanical properties are not possessed in an equal degree by all woods; in fact, there is a very considerable variation among timbers both in appearance and their properties, particularly as regards weight, hardness, strength, degree of shrinkage, easy of working, ability to hold nails and screws, and reaction to pulping agents. Equally notable are the chemical and anatomical differences. The choice of species for any particular use is decided by combined presence of desired properties and characteristics. It should be realized that an appreciable equalization of the properties of wood can be achieved by proper design and treatment.
1.1 Aircraft timber industry
Requirement of timber
Timber is required for the following four purposes: a. b. c. d. For general constructional work and main members. For the high quality plywood used for covering purposes. For propeller manufacture. For linings and for sandwich construction between two plywood skins.
Qualities of timber required
The timber has to be sound, free from knots, straight-grained and light in weight, should possess high strength/weight ratio. 1
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) The growth should be uniform, only pieces with 3 to 6 growth rings/cm being accepted. For linings and sandwich construction, lightness in weight coupled with minimum required strength, resilience and sound-proofing properties are chief consideration. In the international market, a weight of up to 224kg/cu m is considered to be satisfactory.
Timbers suitable for aircraft construction
a) For main members- Fir (Abies pindrow) and spruce (Picea smithiana) alone come up to international standard. b) Aircraft quality plywood- Indian birch and maple are suitable. c) For propeller-Timber suitable for propeller are padauk, aini (Artocarpus hirsuta),chickrassy(Chukrasia tabularis), champ(Michelia champaca). More advanced types of propeller are made wholly or purely of compregnated wood (resin-impegnated laminated and compressed wood). d) Materials for linings and for sandwich construction between two plywood skins- Balsa (Ochroma pyramidalis) is the world¶s best timber for this purpose. Pieces with a density of 128-224kg/cu m are accepted commercially. Suitable substitute of balsa are Cryptomeria japonica (density about 256 kg/cu m),Erythrina suberosa( density 240 kg/cu m) and Sterculia villosa(density about 272kg/cu m) Finally, it should not be forgotten that aeroplanes are being constructed very largely of metal nowadays and that, though the demand for wood will continue for certain parts, the use of wood in aircraft construction is not as much as it once was.
1.2 Boxes, Crates and Packing Cases
In Ethiopia, as elsewhere, packing is one of the important end uses of wood. Wooden packaging has always been preferred for fresh fruits, machinery, aircraft parts, precision instruments etc. Manufacturers of shoes, matches, soaps, chemicals and toilet preparations, pencils, articles of stationery, paints and varnishes etc require large quantities of packing cases. Paper mills and coffee-packing industry also require large quantities of wood for this purpose.
Qualities required in packing case wood
Packaging serves three principal purposes, viz., protection, ease of handling and advertisement. The primary requirements of a wood for use in packing cases are lightness in weight combined with required strength for purpose, and good nail and screw holding power. Timbers weighing about 350-420 kg/cu m in air-dry condition are suitable for packing cases. Timber for packing cases should preferably be of light color so that it may carry stencil marks well, this having an advertising value in trade: the trade would prefer a goodlooking, white good. The timber for ammunition boxes should have good retention of shape and size combined with required strength, particularly for small arms and ammunition.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) Timber for packing cases should be straight grain and free from insect attack, decay, objectionable knots, splits and warping. Timber for cheap type of packing cases should be seasoned to moisture content not exceeding 18%. Timber for better quality of packing cases should be thoroughly seasoned to moisture content of 12-18%, depending on the locality of use and manufacturer.
Classification of packing case timber
Timbers are classified as follows from the point of view of their suitability for packing cases intended for varying loads: Class Density of timber
Class I Class II Class III Class IV
640 kg/cu m and above 481-639 kg/cu m 400-480 kg/cu m less than 400 kg/cu m
The suitability of different classes of timbers according to the loads to be handled is roughly as follows. Types of load Class of timber recommended
Very easy load or up to 320 kg cu m Easy load or 321-640 kg/cu m Average load or 641-1280 kg/cu m Difficult load or more than 1281 kg/cu m
III III & II II II & I
Recommended Ethiopian timber: Assignment- Classify Ethiopian timber based on their density.
1.3 Match box & splints
The match box industry is one of the most important timber-using industries in world. The annual production and consumption run to many trillions of matches requiring several millions cu m of wood. 3
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) A match is a piece of inflammable material generally made of wood, but sometimes also of cardboard or other material and provided with a tip consisting of a mixture of chemicals and other substances that may be ignite by friction. It is the most widely used agency yet invented for obtaining fire. In Ethiopia, matches are primarily made of wood only. Match boxes are also of different types: all wood, all cardboard, or a mixture of both. Match boxes are of µfull size¶, µthree quarter size¶, or µhalf size¶. Full size¶, and µhalf size¶ are common, and measure, respectively, 7.30 cmx3.73 cmx1.83 cm, and 4.60 cm x 3.29cm x 1.55cm, including boxes and splints.
Quality of a match wood
The essential qualities required in match wood are: straightness of grain, good strength and toughness combined with lightness, good white color, freedom from knots and cracks, and capacity to absorb paraffin readily and hold the head firmly. The log should be round and easily peelable on the veneering lathe, and the wood should be easily available.
Suitable wood for match industry
Bombax ceiba, Dysoxylon malabaricum, Endospermum melaceense, Salmalica insignis,Spondias pinnata. Efforts have been made from time to time to manufacture splints and boxes from bamboos, reeds and grasses, but the results have seldom been satisfactory.
1.4 Pulp wood
Wood is an important raw material for the production of pulp, and is at present the one most widely used in the world for paper pulp. While woods of coniferous species are more widely used than those of broadleaved species, the demand for paper and pulp products is so great that the woods of broadleaved trees are being employed in ever-increasing amounts. Woods of various coniferous and broadleaved species are suitable for pulping. Some suitable species are listed below: Fir (Abies pindrow) ,Green wattle (Acacia decurrens), Siris (Albizia chinensis) , Salai (Boswellia serrata) , Suji (Cryptomeria japonica), Blue gum (Eucalyptus globulus ), Spruce (Picea smithiana), Chir (Pinus roxburghii) ,Poplar (Populus ciliata)
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Unit 2 Wood uses for transportation industry
2.1 Carts and Carriage
The various parts of a cart or carriage are subjected to different kinds of stresses and strains, and require different qualities of wood for real efficiency. The main parts of a cart or carriage are: i) the framework ii) the axle, iii) the wheals and iv) the shafts or poles.
Framework
A strong wood which is not too heavy is preferable for this purpose (Gmelina arborea) is an excellent timber for light carts. Sissoo (Delbergia sissoo) is one of the best woods in the market for the framework of carriages
Axle
A very hard and tough wood is essential for this purpose. Such timbers as babul (Acacia nilotica, axel wood (Anogeissus latifolia) 5
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Wheels
Wheels are composed of three main parts: the nave or hub, the spokes, and the felloes. Each of these parts requires certain distinct quality in the wood used. Hub ± the wood for this purpose must be straight grained, strong and elastic. It should also be free from defect and not liable to warp or sharing, the later fault resulting in the spokes becoming lose in the mortise of the hub and felloes. The best woods for the purpose are rose wood (Delbergia latifolia) sissoo, dhaman(Grewia tiliaefolia), and bijasal. Felloes-These are subjected too much crushing and alternation all of wetting and drying, and must be hard, strong, elastic and durable. To make a really strong wheel, naturally curved or bent timber is the best, so that the grain of the wood follows the line of the circumference of the wheel as nearly as possible. The best woods for the felloes are babul, rosewood, dhaman and bijasal.
Shafts or poles
Woods for this purpose should be straight grained, tough, elastic and very strong. The best woods are Grewia spp, Anogeissus spp., and similar very strong wood. Pterocarpus dalbergiodes, and Shorea robusta are of the type likely to be most suiable. Bamboos are very commonly used for buggy shafts, being light and strong.
2.2Railway carriages and wagons
The manufacture of railway carriages and wagons is an important timber utilizing industry in the world. Although frames of carriages and wagons are now a days invariably made of steel, wooden bodes are also in use. The proportion of wood used is gradually decrees as the railway are bringing in to use carriages with steel shell in which the use of wood is restrict to interior fitting.
Qualities required in the wood
Wood used for railway carriage building should generally be strong but not very heavy. As explained below, other properties have also to be taken in to account with reference to the specific parts of the carriage for which the wood is to be used. The timbers required for carriage and wagon building fall in to the following for distinct class: a) Fore main members of passenger coaches, such as bottom sides, pillars, can¶t rears and cross bars: a generally strong and very steady wood is required for this component. For along time, only Burma teak (Tectona grandis) was being used, but now Indian teak and padauk (Petrocarpus dalbergioides) have been accepted as equally good substitute. b) For interior fittings such as boarding, paneling, ceiling , partitions seats, etc« most furniture class woods can be used for this components, the main requirements being moderate strength, reasonably good retention of shape and size in service, and good figure,grain and color. c) For foot -boards± hard and strong timbers are needed for this use
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) d) For floor boards : hard and strong timbers are needed to with stand the continual wearing out and indentation stresses to which floor boards are subjected
2.3 Railway sleepers
The chief functions of sleepers are to support the rails, distribute the load from the rail to the ballast, and maintain a gauge. Wooden sleeper fulfils all this requirements very satisfactorily. The average annual requirement of sleepers of all categories is assessed to be at about 10 million. As supply of wooden sleepers is limited, the railways are trying to effect a gradual reduction in the use of wood for sleepers and are going for sleepers of cast iron, steel and pre-stressed concrete.
Qualities required in the wood
The wood for sleepers should have strength, including transverse strength to resist breakage by centre, binding and compressive strength to resist the pressure. It should be hard to resist rail abrasion. It should have spike holding power to resist undue spike loosening and good seasoning property without excessive splitting, cracking, warping etc. For all treated sleepers, the timber must be amenable to treatment with coal tar creosote or other preservative at reasonable cost.
Suitable timbers
1. Untreated sleepers- Shorea robusta, Cedrus deodara, Xylia xylocarpa, Lagerstromia purviflora, Ptreocarpus marsupium. 2. Treated sleepers- Shorea robusta, Cedrus deodara, Abies pindrow, ,Albizia lebbeck, , Anogeissus latifolia, Pinus roxburghii, Pinus wallichiana, lagerstromea lanceolata.
2.4 Road paving blocks
The use of wood for paving streets is said to have originated in Russia. It was later introduced into England, America and elsewhere. The method consists in embedding small blocks of wood in bituminous compounds. Even in the modern days of reinforced concrete and other compositions, wood has certain qualifications as a street-surfacing material which none of the other materials so far discovered for the purpose possesses. In the first place, wooden paving-blocks compare favorably in cost with other surfacing materials and offer better resistance to the skidding of motor cars than concrete or composition surfaces. They also compare very favorable in durability and wear and tear with other roadsurfacing materials. Above all, they are silent under heavy traffic, which in street fronted with offices, shops, hospitals etc is an important consideration.
Characteristic required in wood
The chief requisites of good wooden paving-block are durability, resistance to wear and tear, resilience, and non- liability to absorb water excessively. The texture should also be even, as otherwise the blocks wear unevenly. 7
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) The general rule is that the paving- blokes should be laid with the cross-section surfaces at top and bottom and not on the sides. This is necessary to ensure even wear and tear, as the end-surface of wood wears far more evenly than the tangential or radial surfaces.
Wood recommended and in use
Irul (xylia xylocarpa), Tectona grandis, Acaia catechu, Hopea parviflora.
2.5 Ship and boat building
In former times, before the advent of iron and steel, the demand for ship building timbers was one of the heaviest on the timber industry. The demand is even now very large, but the purposes for which the timber is required have changed. Nowadays wood is confined chiefly to deck planking and interior fitments. This, of course, is only natural when it is remembered that iron ships are stronger and more able to resist the buffetings, of heavy seas, are more durable and easier to repair, and can be built to sizes far beyond the possibilities of wood. The shipping of today is many times what it was years ago, and the demand for deck planking, cabin fitments and interior decorative woods is greater than ever.
Requisite properties of timber
Timber for ship building should be strong, elastic and durable and free from defects to stand the enormous strains. Teak(Tactona grandis) is the best wood ship building timber in the world not only because of durability, strength,
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Unit 3 Wood uses for sports good industry
Sports goods include a large number of articles, such as hockey sticks, cricket bats, tennis and badminton rackets, golf clubs, billiard cues, skies, cricket stumps and bails, fishing rods, etc. The requirements of wood for sports goods are very exacting. Timbers with a combination of certain specific properties are needed and the choice of species is limited.
Requisite properties of timber
The requirements of wood are very exacting. It must be light with high strength/wt. ratio, pliable, tough, shock resistance, easy to work, capable of taking a good polish and preferably light in colour. In Europe and America, ash (Fraxinus spp.) is commonly used for the purpose, and in India mulberry became the standard sports goods timber as a substitute for imported ash. Different qualities are however, required for different articles of sport. The different categories of sports goods and the woods used or found suitable are discussed below.
3.1 Billiards cues
Timber for this purpose has to be right weight and must have a straight grain. It should be white in colour or nearly so, free from knots and other defects. Recommended Species: Ebony (Diospyros melanoxylon), Polyanthia fragrans, Sageraea elliptica, have been tried and found suitable. 9
SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
3.2 Bows and arrows
Yew (Taxus baccata) is an excellent bow wood. It is very strong, tough and an elastic wood. Other woods used for this purpose are Grewia tiliefolia, Pterocarpus marsupium, Acacia catechu. For arrows good strong wood which will not warp is required. Coniferous are sometimes used but are too light for the purpose. Delbergia sisoo, Pterocarpus marsupium are suitable. Reeds and bamboos are also commonly used for arrows.
3.3 Cricket bats, stumps and bails
The timber for cricket bats should be light in colour and light in weight but reasonably strong. It should be able to take the shock of repeated striking of the ball with great force. The best and the only wood used for bats is willow (Salix spp.). The best cricket bats are made of the English cricket bat willow( Salix alba var Caerulea) of the U.K.. Cheap quality bats can be made from Melia azadarach, populous Spp. Mulberry( Morus alba) is most commonly used for stumps and bails but other woods like Celtis australis, Polyalthia fragnus are also suitable.
3.4 Fishing rods
For cheap rods, bamboos are chiefly used, Arundinaria falcate being amongst the most popular. Wood most commonly used for superior quality fishing rod is green heart (Ocotea rodioei), a South American species. Some other species like Terminalia manii and Sageraea elliptica have also been found suitable.
3.5 Golf clubs
Wooden golf clubs are usually made of South American hickory (Carya spp). Ash is also used for golf club shafts. Golf club heads are made of persimmon (Diospyros virginiana). Terminalia manii, Acacia nilotica, Chloroxylon swietenia, Tamarandus indica, Mesua ferrea have been used with success for heads of wooden clubs.
3.6 Hockey sticks
The timber for this purpose should be reasonably light but strong, particularly in its shock resistance. It should be amenable to steam bending in thick sections. Ash is commonly used in western countries. Mulberry (Morus alba) has been found suitable for hockey sticks. Amongest other substitutes Celtis australis also makes a satisfactory hockey sticks.
3.7 Tennis, badminton and squash rackets
All tennis, badminton and squash rackets of built-up construction obtained by bending and gluing together thin veneers of wood.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11) Straight grained, long fibered wood with good shock resistance is essential for rackets. Ash (Fraxinus spp), maple (Acer spp.), are commonly used in the western countries. Mulberry is also found excellent for the purpose. Other suitable woods are lagerstroemia hypoleuca and lagerstroemia lanceolata.
3.8 Skies
Toughness, flexibility, even texture, and straight grain are the essential qualities of a good ski wood. Ash and hickory are used in Western countries. Delbergia sisoo, Morus alba and Axel wood (Anogeissus latifolia ) have been found suitable for the purpose.
Unit 4 Wood uses for agricultural implements, post & poles
4.1 Fence posts
In many parts of Ethiopia, a short pole cut from a young or small tree is used as a fence post, usually in its natural round shape and often with the bark on. Such a post contains a large percentage of sapwood, and as the sapwood of all species, including that of sal (Shorea robusta), teak (Tectona grandis), deodar (Cedrus deodara) and other trees with durable heartwood, is very liable to attack by fungus and insects, and as the bark on a dead stem is sure to attract wood-boring insects, a post of this type is not really serviceable. If the bark and sapwood are chipped off before use, the result will be more satisfactory, and such posts will give good service, at any rate for temporary
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
purposes, if the species used has reasonably durable heartwood. In most localities in Ethiopia, owing to the prevalence of termites, fungi and borers, the heartwood of a fairly durable species should be used for fence posts, or the posts should be treated with a good preservative. It is usually sufficient to' treat only the lower portion of the post, as the portion above ground is often not subject to adverse influences, but the treatment should extend up to a quarter of a meter or so above the groundlevel part of the post. A simple butt treatment in an open tank or barrel is usually adequate; but, should the post be required to give service for '1 number of years, a thorough treatment in a pressure cylinder is necessary. A very useful and moderately durable post can be obtained by charring its surface over a fire before planting it in the ground.
Qualities required in the wood
Reasonable strength and durability are the only qualities required.
Woods in use
The following timbers are likely to give good service: babul, khair (Acacia catechu), deodar, hopea (Hopea parviflora), pterocarpus spp, Sal, teak and irul (Xylia xylocarpa).
4.2 Fresh w ater piles
As marine borers are confined to brackish or saline water, constructional work in freshwater is not subject to attack by these pests, and the selection of timbers for this type of work is thereby greatly simplified. The type of structure for which the timber is required, however, plays an important part in selecting the best wood for the purpose. If the structure is to be completely Immersed in freshwater at all times, selection is easy, as submerged wood is protected from attack by insects and ordinary fungi, and several woods which are considered as most perishable when exposed to the air give good service indefinitely if kept under water. Good examples of this are salai (Boswellia serrata), Erythrina suberosa, mango (Mangifera indica), semul (Bombax ceiba) and bahera (Terminalia bellirica). All these woods are perishable timbers in ordinary circumstances, but if kept completely submerged under freshwater, they remain almost indefinitely in good condition. If, on the other hand, the structure is to be exposed to alternate wetting and drying, the situation is entirely changed, as conditions most favorable for the rapid development of wood destroying fungi are at once set up. Unfortunately, in such constructions as piers, jetties, bridge piles, well
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
curbs, sluice gates, and river-bank protection against erosion. Alternate wetting and drying is unavoidable, and unless preservative treatment is adopted, it is necessary to use only those timbers that are durable under these conditions. The choice is, therefore, restricted to such wood as babul, Artocarpus spp., deodar (Cedrus deodara), hopea (Hopea spp.), Lagerstroamia spp and teak (Tectona grandis). Of these, uriam and pyinma (Lagerstroemia hypoleuca) have been reported on as being exceptionally durable if kept wet.
4.3 P iles
Piles comprise the main upright members in bridge building, etc. They usually have the lower portion of their length sunk in the ground. This portion, and more especially that near the ground level on dry land, is very liable to at tack by termites and fungi. The portion of the pile below water level is not subject to attack from termites or fungi. Quality required in the Wood The essential qualities required in a good pile wood are great durability (the most important) and great strength and resistance to shearing, splitting and endcrushing, it must be capable of standing up to the continuous blows of the pile driver during the process of being driven into the ground. Woods in use Amongst the best of the woods for the purpose are: babul (Acacia nilotica ssp indica), khair (Acacia catechu), aini (Artocarpus hirsuta), deodar (Cedrus deodara),hopea (Hopea paroijiora), sal (Shorea robusta), teak (Tectona grandis) and irul (Xylia xyIocarpa).
4.4 Telegraph, telephone & electric poles
The scope of use of wood poles
There is an increasing demand for cheap types of supports for' overhead power and telecommunication lines. Owing to the prohibitive cost of tubular poles, various other types of supports such as concrete posts, used rails, and wood poles have been tried for this, purposes. Wood pole lines are considered to be the cheapest as regards initial cost as compared with all other types of supports. On account of their very elastic nature, wood poles are used both for shortspan low-voltage systems, and also to a limited extent for high- voltage transmission lines.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
Essential and desirable properties of wooden poles It should be obtainable in good straight length. It should not split or crack excessively, and should have the required length. It should be free from sap rot, hollows, cross breaks and large holes all of which are categorized as a totally prohibited defects.
4.5 Tent poles and Tent pegs
Tent poles Tent poles are usually of bamboo, but it is not uncommon to see large tent poles made of wood; such poles can be either round or squared. A good strong wood is desirable, Common timbers in use are dhaman (Grewia tiliaefolia), sal and Teak (Tectona grandis). Tent pegs Tent pegs may vary in size from the small 15 cm pegs, used with very light tents, to the very large pegs '1 m long and 10 cm in diameter used with big marquees. These must be made of a hard, durable wood, which should also be tough enough to resist hammering. There is a big demand in the country for suitable woods for tent pegs of all descriptions. Many woods are suitable for this purpose. Among the best of these are babul (Acacia nilotica spp indica), sundri (Heritiera minor), sandan (Ougeinia oojeinensis), kusum , sal Tamarindus indica) . Other good tent-peg woods are sissoo (Dalbergia sissoo), dhaman (Grewia spp.) and irul (Xylia xylocarpa). The most common type of tent peg is a round peg cut from a branch or sapling, This type of peg is liable to crack, the wood being, more often than not, quite green. A more satisfactory peg can be sawn from a plank of seasoned wood to the size and shape required.
4.6 Agricultural implements
"Agricultural implements" is a comprehensive term with a wide application, but in common use it usually refers to such appliances as ploughs, harrows, rollers, and clod-crushers. In Ethiopia, these implements are, more often than not made entirely on wood, and the amount of timber used for their construction is quite considerable. Only the strongest, toughest and hardest woods are of any use for such world and the local wood which complies best with these essentials is the one usually employed. The following some woods are all used for agricultural implements of different kinds: Acacia nilotica, Acacia catechu, Axel wood, sissoo, oaks, sal, irul etc.
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
I.
Unit 5- Wood uses for textile & jute mill accessories
II. III. IV. V. 5.1 Bobbins 5.2 Shuttles 5.3 Picker arms 5.4 Loom components
Sp"cin ill use .--1 IalJu 1 ! I! l'; '''rdj-nit I ..'1
. ' ; Lhe (;{)mmqnh" \Is·>d wood for most kinds of bobbins. For thinner"walled pirn~, rnaplr: (Acer spp.), birch (Betula spp.) wh;te cular (D)so.'..lulIl ma{abalicum), and mullilarn (FagfiTa budnmlfa) are p~elerred, bu~ these woods are in short suPUly ThcI'cfore, imported maple, birch and beech are still being used to some extent.
Species recommended.-Of Indian woods, maple, haldu, birch, white (1\1itrag)'t1a parvifolia) are recommended. (ii) .lute-mill bobbins
cedar, mullilam and kaim
Jute-mill bobbins are usually larger and thicker-walled in design, and the requirements as to finish are not always as exacting as in the case of cOHon-mill bobbins. Moreover,. introduction of 3-ply ends of wood construction and composite metal- and wood-desIgn has enabled the use of several cheap-grade secondary species. Species in use.-Mango (Mangifera indica) and silver oak (Greyillea robust a) are most commonly used, while haldu and kaim are also occasionally used. No imported timbers are used. Haldu Chaplash (Artoearpus chaplasha) Birch Toon (Toollo ciliata) Cll ickrassy (C/wkrasia tabularis) G?mari (Gmelina arborea) SilvFr oak Kal'ju J-fulnpte!ea intrg1'ljalia) Kw han ([1) menOdl(t)Ofl .:xce!sum) 1\1ango Ch?mp (.'vfiehelia eharnpcca) Bon,um (Phoebe spp.) (b) For slwlU\s Haldu Toon Chickrassy Silver oak ~rango Kaim Sppcie, ill /lSt'.-Babul './<I.(ia Ili!utir(l ssp irdie,!). axl(wood (Anog,issl<S latijoli.I), tht !.igh t-colfJlH cd s; p W lJcd e,f ~b, Ii) U)i.';,~t:Jrn~ IIdar'{'X);(lI~, ci!l<,!1,;,ln S:rcil ia tifi,;eJO.':.l'. ~ll.,d l.endi (Lagemru/'mia Ix/rvif!,ura) arc fi01\ being uscd to an inere, , extent. . A .lm,,' amount of imported hicko:y is howt:\,er still used. parti"'ula,"'~ for jttte·mlil pIckel.' arms. Lamina/cll-wood pi ekcr ;lrms madc of thc aoove limbers have recently been introduced and have been "ery fa ""ourably reported upon, Species recornmended.--Dhaman w"s found to be as good as' imported hickory in small·scale service trials
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SPECIALIZED USES OF W00D: Department of Wood Science & Engineering, SoEIT, Adama University (2010-11)
c<lrried out in eottor--miJls by the Forest Research Institute, Dehra Dun, whilc babul, Iendi, and sardan (Ougeinia oojeinensis) were favourably reported upon. Other suitable timber.s "me: axlewood, sissoo (DalbergiQ sissco), ebony (DiosRyros melanox)'lon), and laurd p:;;rmir.alia tumcnlosa), only the light-coloured Qutn' wood being used in the case of ebony. Properties essential or desircble,··- 'I he tin,ber she uld be straight-gl'aincd and fineand even-te...,,;:tured. It should turn well and should be smooth to finish. It sho ld not split when metal fastenings are inserted. It should be reasonably strong, but should have considerable resilience and resistance to splitting. It should have good wearing quality and sh uld wear smooth in prolcng(d friction against the loom-race pI,2te and yarn. The timber shodd preferably he of weight about 8:30 j,g/cu m (air dry). It should season wen without much degrade. Species in use.--Imported cornel, persimmon or horn bet-m (Carfinus spp.) is still preferred. Rosewood (Dalbergia latifolia) and the light-co loured sapwood of ebony (Diosp)'ros melano:<ylon) are indigenous timbers now being used to some extent. Compressed blocks with the sapwood of (DiospJToS melano:>:jlon) for the core arid laminated wood for the two sides have been introduced reclntly to a limited extent. Efforts are under way to introduce more extensive use (;f laminated and/or compre3sed wood. Species recommend, d,--'I h e ligh H .G lc ured sa p" (, c,d III DiGS!!) ros I/ulunox.)ivn . ,'as found to be thi; nearest to and a l'casona !')ly goed substitute for imported cornel for shuttles in service tests carried out in cotton-miils by the Forest Research Institute, Dehra Dun. The hIll tirr"bers 'Kharsll cak (Q].ereus semecarpifolia) and parrotia (Parrotia jaequemollliana) apI-car to be very promlsll g on the of their physical and mechanical properties. Other timbers worth tf) ing for the purpose are rosewood, gardeni.l .Gardenia latijc,fia), sandan. al':1 rnoh-I.;, ,S,hlt'bera swicteniaides). Laminated and/or co In pessed \\ ood has Lright prospects.
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