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Cavity mold cooling construction design
In commonly mold designer know that Cooling conditions affect cycle time, part dimensions, surface finish, and warpage. but some junior mold designer still confuse to make layout and construction of cooling in mold. before this posting, i havepost about cooling construction in slider, beside slider mold cavity also important to fill cooling, why because almost product 70-80 % is molded shape in mold cavity.

picture above shown core side of cavity mold, the basic construction is 1. Plug (Plug is for prevent water flow out from desire flow layout) 2. cooling pipe (as those picture cooling pipe doesn't shown, almost cavity cooling pipe processing using jig bor to make a long hole that becoming cooling pipe) 3. In / Out Hole, it's hole also make using jig bore. this hole will attach in cavity plat that will match with cooling layout in mold base. orange color indicate product insert hole shape. here i post basic construction in single cavity, see picture below to learn more

picture above is shown flow of cooling process of cavity mold from top view. then which hole water flow in and flow out, see picture below

at this wireframe method picture, we should make hole at bottom side of core to connected cavity and cooling layout of mold base. Tips Design Cooling pipe for cavity 1. make sure side of cooling pipe have enough length from insert, minimum 3 cm 2. choose a good diameter for the hole, like 6 cm, 8 cm, or 10 cm.

3. when injection proses begin make sure using calculation so you have turbulent flow in cooling pipe. 4. make the pipe more long is useful for make turbulent flow.

then how the layout and construction of cooling in mold base ? just wait for new post

Mold Cooling Design at Slider
Why mold need cooling ? as we know that cooling conditions affect cycle time, part dimensions, surface finish, and warpage, Mold cooling time is the biggest contributor to the overall cycle time, it could be as two-thirds or 70-80% of total cycle time. from those reason design an efficient cooling circuit can reduces the cooling time, beside that uniform cooling improve part quality by reducing residual stress, stability of heat transfer, and accuracies of part after cooled. Why Slider Need Cooling? Some product have long dimension that need slider, to prevent warpage, residual stress, and stability of shrinkage behavior, for that reason slider need cooling. Mold Cooling Construction picture below shown cooling construction at slider insert from top side.

annotation number at picture upper indicate part of slider, they are 1. Plug 2. Slider Insert 3. Cooling Pipe 4. Guide Rel of slider core 5. Locking Block slider 6. Long Nipple Pipe with blue color indicate flow of water when cooling process working. number 1 part (Plug) prevent water flow to side of slider inserts. When design nipple,make sure that nipple is long enough to reach outer side of mold base. to get understand more look at picture below, at this picture still shown cooling at slider from left side.

additional number of slider parts are 7. slider core (this part is one of slider main part, where slider insert attached) 8. Angular slider ( the main function of angular is change the moving 90 degree, so slider can move)

Plastic Processing Methode Types
Today, they are various plastic processing method available in industrial process, from the method of processing plastic we can divided into two big methods they are :

1. Molding Methode this method usually use mold to melt the plastic, deformed with applied pressure and the product shape will same as the mold shape. Various molding type method can be divided as

Extrusion Molding Method this process can produce along product with fixed cross-sectional profile such as wire and cable coating, plastic tube for printer ink, some hollow profile and various solid profile. the material is pallet or plastic chips that are usually dried in a hopper before going to the feed screw. to process extrusion method used injection machine, The plastic heated at barrel to molten state then forced through a plastic mold die that is in desired shape. look at picture below to learn more about extrusion mold.

Injection Mold Injection molding involves taking plastic in the form of pellets or granules and heating this material until a melt is obtained. Molten plastic is injected at high pressure into a mold, which is the inverse of the product's shape then it is allowed to cooling into the desired shape. The mold is then opened and the part is ejected, at which time the cycle is repeated. you should learn about various injection molds type at mold construction post injection mold method have various kind of techniques like Thermoplastic Foam Injection Molding, Multi injection mold (sandwich mold, bi injection mold) gas assist injection molds and other, basic injection machine for injection mold you can see at picture below

to learn more about injection mold you should open introduction of injection molds post Blow Molding Process A thermoplastic resin is heated to a molten state It is then extruded through a die head to form a hollow tube called a parison. The parison is dropped between two mold halves, which close around it, the concept of blow mold you can see at picture below

we can divided blow mold four types as : * Extrusion blow molding * Injection blow molding * Stretch blow molding * Reheat and blow molding. the picture above shown Stretch blow mold type, you should see more at Blow Mold Posting Compression Molds Compression molding is a method of molding in which the plastic, generally preheated, is first placed in an open, heated mold cavity, they are four step in compression molds they are loaded charge, charge compressed, cured the charge and ejecting process of product. the main construction is Punch (cavity side), core molds and ejection system.

Reaction Injection Molding (RIM) the concept of RIM is Two reactant liquids are heated and brought together under high pressure. one example process is polyurethane RIM, At the heart of the polyurethane RIM process is a chemical reaction between the two liquid components, which are held in separate, temperature-

controlled feed tanks equipped with agitators. From these tanks, the isocyanate and polyol feed through supply lines to metering units that precisely meter both components, at high pressure, to a mixhead device (http://www.rimmolding.com/rim/index.html), look at picture below, those picture shown two chemical reaction process mold isocyanete (blue tank) and polyol (red tank)

. the advantages of RIM is Strong, flexible, lightweight parts which can easily be painted. Quick cycle times compared to typical vacuum cast materials, the disadvantage is slow cycle time because must mixed before formed by mold. Transfer Mold transfer Mold or resin transfer mold (RTM) like compression molding, is a process where the amount of molding material (usually a thermoset plastic) is measured and inserted before the molding takes place. The molding material is preheated and loaded into a chamber known as the pot. A plunger is then used to force the material from the pot through channels known as a sprue and runner system into the mold cavities. The mold remains closed as the material is inserted and is opened to release the part from the sprue and runner. The mold walls are heated to a temperature above the melting point of the mold material; this allows a faster flow of material through the cavities.

Thermoforming is a manufacturing process for thermoplastic sheet or film by Heating a thermoplastic sheet and using a vacuum to pull the sheet over perforated mold. the product of this method is Fast food containers, advertising signs, panels for shower stalls

Pultrusion Pultrusion is a continuous process of manufacturing of composite materials with constant crosssection whereby reinforcing fibers are pulled through a resin, possibly followed by a separate

preforming system, and into a heated die, where the resin undergoes polymerization. Many resin types may be used in pultrusion including polyester, polyurethane, vinylester and epoxy.(Wikipedia)

2. Casting Mold Casting is a manufacturing process by which a liquid plastic introduced into a mould, allowed to solidify within the mould, this characteristic of this molds is filling a molds by gravity, this kind type of casting molds are : Liquid resins (epoxy) Hot melted plastic poured into a casting (nylon) Slush casting for thin walled products (snow boots, gloves, toys) Wet spinning -fibers formed by spinning the solution through multi-hole dies Rotational Mold Rotational molding or moulding is a versatile process for creating many kinds of mostly hollow plastic Parts. The phrase is often shortened to rotomolding or rotomoulding. molding of large products such as storage tanks and containers, cPrnpIex toys, mannequins (display figures), etc., is achieved using rotational

molding. Lately, there are more and more applications for this technology.

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Pin Point Gate Construction
pin point gate is commonly used in 3 plate mold types, see explanation more about 3 plate more here, basically the pin point gate part is like picture below

those picture is pin point gate picture, to make gate like that we can buy pin point gate bush in mold manufacture company or we make it by EDM (electronic Discharge Machine) Process, the special EDM torch for Pin Point gate also available in mold part markets. Pin Point gate Bush picture below shown simple pin point gate bush,

the construction to assembly the pin point gate bush in mold is like picture below straight, without extended bush, picture below shown, locating ring, pin point gate bush, runner lock pin, runner, product and mold base plate (top plate, stripper plate and cavity plate)

some times, we need extended pin point gate bush, why when plastic material have high shear rate, we need to assembly extended bush, so from diameter gate until runner plastic material will easy to flow the cavity. see the construction at picture below

here some good link of standard component of gate,

Basic Functions of Mold Base Parts
A mold plate is any plate required to built a complete mold, in all plate use for molds have the main requirements, they are : 1. Good corrosion resistant 2. Good Machinability. 3. Easy to clean 3. Good heat transfer. 4. Homogeneity of steel. 5. Easy ability. 6. Low Cost. at picture below you can see 3 plate mold base type with closed position, basically 3 plate type and 2 plate type has some main plate, see explanation about mold construction type to understand more,

explanation below based on number at those picture 1. Fixed Clamping Plate or Top Plate Holds The fixed side of the mold to attached at the fixed platen of the injection machine. at this plate will attach locating ring, eye bolt, and sprue bush. 2. Runner Stripper Plate

this plate only used in 3 plate molds type, the function is to cut resin from nozzle in top of sprue bush, and pull the runner by runner locking pin. 3. Fixed Mold Plate or Cavity plate. use to hold cavity side of product, leader pin, support pin, Puller bolts, and Angular pin when slider attached. 4. Movable Cavity Plate or Cavity plate it used to attach core side of product, return pin, leader bush and slider core if needed. 5. Back up Plate or Support plate used to support cavity plate, attach the hole for return pin's spring, and cooling channel when in cavity plate can not make it. 6. Spacer Block Mounted between the movable clamping plate (bottom plate) and the movable cavity plate to give space and allow the ejector plate to move when ejecting the part. the required length of spacer block depend on ejector stroke that needed to eject product. 7.Ejector retainer plate to hold the ejector, Z pin, shoulder bolts,and give space to ejector leader pin and support pillar. 8. Ejector Plate Pushes the ejector pins and return pins, connected with ejector rods. 9. Movable Clamping Plate or Bottom plate Holds The movable side of the mold like spacer block, support plate, cavity plate and ejector mechanism to the movable platen of the injection machine.

and look at picture below, shown 3 plate molds type in opening position, but at picture below, Bottom plate or movable clamping plate is number 7, number 8 is ejector retainer plate, and number 9 is ejector plate.

Top Plate, Stripper Plate,Sprue Bush and Runner Lock Pin Design
at the picture below you will see a set of Top plate until stripper plate design related with runner flow, at this picture support pin exclude. the mold type in this picture is 3 plate type. the runner system accommodates the molten plastic material that coming from barrel, and guide it into mold cavity, the dimension, configuration, shape, and system connection with mold cavity will affect filling process.

as see from that picture, red plate indicate isolated plate, it's doesn't matter you use isolated plate or not, but you must see more in injection machine, if it needed isolated plate give it. number 1 and 2 in black plate it's indicated top plate for number 1 and stripper plate for number 2, those picture shown 3 open mold type. after injection, in ejection process stripper plate will open because puller bolt pull it( not include at those picture). runner ejector set will needed to push runner, after ejection, but if you use arm robot or manual take the runner by hand operator it doesn't needed. runner ejector set always contains spring, those spring will push pin in ejector set and will push the runner. runner lock pin function is to pull runner when ejection begin still in top plate, if runner adhere in stripper plate, the robots or operator will difficult to take the runner, because no ejection

system for runner in stripper plate. when design the runner system and ejection system for runner in 3 plate type of mold you should use those mold accessories.

When we need slider parts in Mold Design
second previous post i have post about the slider parts and construction in complete mold base , then now i give a little brief when we need slider in mold design, basically we design mold from our customer, first is we must look the parts that we will make by plastic mold, look mare at the drawing so we can know about tolerance and critical point of parts, seconds is define the parting line, first parting line is between core and cavity parts, and after that if the parts have side form we must define slider parting line, look picture below

from those parts we know that we need slider parts, side hole and other shape that can not form by core and cavity became slider parts. below is picture in 3D modeling,look at the hole shape in side, those shape need slider part.

and how the construction of slider, more about construction mold you can see by clicking mold construction or molds parts in quick topic, basically here i give slider 3D modeling and parts name, those parts names i take from Misumi standard mold design

you can use this tutorial for education and others purpose but still write copyright from this site.

SPRUE BUSH and LOCATING RING
when you choose sprue bush, make sure you was know the diameter ball nozzle of plastics injection (SR) is less than diameter ball (SR - at picture below indicate by R) if diameter R of Sprue bush to little than nozzle SR diameter, that will not good match or touching, if injection machine working plastic flash will out between nozzle and sprue LOCATING RING some mold designer usually use Locating ring to prevent unmatching nozzle of injection machine, before choose inside diameter of locating ring, we must know the outer diameter of nozzle that will touch with locating ring, at the picture below written in purple Red color indicating flow of plastic material, from this picture we can take a conclusion that the picture is 2plate type of mold, look at picture there is no runner plate, and the gate type is side gate

Z pin Ejector is used to make the runner ( RED COLOR) still adhere in core side when mold open and take the product, then Z pin will push the runner

Circular H type Runner Layout in Mold Design

It¶s called H type because the runner shape from the top similar with ³H´, it¶ use in both circular layout and rectangle layout system, in circular type the runner doesn¶t similar with H but it more

similar with fork, circular type use in various type of product, like gear, cylinder shape, etc. Total length of H circular type in each part of runner 8.801 x 16 = 140.816 7.491 x 8 = 119.856 18.83 x 8 = 150.64 Total length of runner in H circular type runner system 140.816 + 119.856 +150.64 = 410.912 Let¶s compare with previous type runner system, direct runner system both circular and rectangle type, Direct circular type = 448 mm Direct rectangle type = 495.04 mm H circular type = 410.912 mm So the conclusion is from three example runner systems for these part and layout type, H circular type has the minimum length of runner,

Advantage 1.Flow length in the runner more stabile, cause we can add runner slug before branched the runner, see picture above 2.When designing the runner, runner volume is made small as possible, this type is smallest than two type runner before. 3.All the cavities fill at the same time possibility is high, balanced runner have an equal flow length and runner size form sprue to all cavities also same, so that each cavity can fill in nearly condition.

direct circular runner system and direct rectangle runner system in mold design
continuing previous post about sleeve ejector system in mold, now let's learn how to choose runner layout, and lay outing the cavity and core,

From picture above space that available for layouting cavity core is 40 mm X 40 mm, from those available space we must design effective and cheap runner cost, effective design for runner mean that total runner length designed as short as possible, and runner, product weight ratio is small, so it¶s your product will contain only short runner, that can reduce cost of material. Here some layout that I tries to make from available space 40 mm X 40 mm. Direct Circular Type This type is easy to layout, because we only design for one runner, straight between center of sprue bush to gate position, then copy those runner base on amount cavity that can be layout, from space that available 40 mm x 40 mm, we can arrange the cavity until 16, so the angle between one cavity and other is 360 / 16 = 22.5, to arrange more detail copy and rotate your runner design with those angel (22.5) until you get 16 runner, each runner length is 28 mm, so total length of runner are 28 x 16 = 448 cm. See picture below for detail construction and dimension of circular runner system for this mold

Top view

Direct rectangle type Simple way to layout cavity core and runner is using direct rectangle, this type common use in imprecision part, 8 cavity will have length 28.6 mm from center sprue bush, and the 8 cavity others will have length 33.28 mm, see picture below for detail sketch of runner. From this condition total length of runner are (28.6 x 8) + (33.28 x 8) = 228.8+266.24=495.04 mm, this runner type have 47.04 longer than previous type.

The other¶s disadvantage of this runner type is flow material will not same to all cavity, because distance between cavity and center of sprue bush for all cavity have 2 type, first type have 28.6 mm, second type have 33.28 mm in length, if the injection pressure too high or injection volume of material too much, it possibly flash at the first type (28.6) cavity. And if volume injection doesn¶t enough shot mold possibly appear at second type cavity (33.28)

so, in this case, circular type of runner layout still the best to be implemented, how about the other runner layout type, such us H type, let's see on the next post

Fill time runner balance on 6 cavity of mold
runner balance is important when we works with more than 1 cavity in mold design, unbalancing runner can cause various like unfill mold (short shot), weld line, air traps, burning and others. from previous post that talk about design of runner balance in 6 cavity, now let's prove it by simulation of filling time. Unbalance Flow Definition Unbalanced flow is plastic completely filling some flow paths in the mold before other flow paths have filled. we can see from result of simulation, if color is same in cavity (for example at the end and gate) that mean it have good flow. 1. Unbalance Runner System

from picture above we can consider that flow of plastic in various cavity doesn't fill in the same time, it can cause flashing, short shots, high cycle time, density differences throughout the part, warpage, air traps and extra weld lines. flashing will occur in cavity that fill earlier, becouse cavity that fill earlier will continue receive plastic flow until other cavity filled (it depend on injection pressure and cycle time set up). Short shots happened at cavity number that fill more slowly then others cavity then the pressure and cycle time doesn't enough to fill the last cavity. 2. Balance Runner of 6 cavity although this runner layout is not the best for 6 cavity layout, it better in fill time than runner layout before. look at the picture below

by changing the layout we can get runner that more balance with previous, from cavity number 1 until 6 the fill time is almost same.

Runner Balance Layout for 6 cavity of mould
Picture below shown layout model for 6 cavity product, star layout used to connecting 3 cavity, then connected again with straight line. distance between one cavity to another is same Top view

3D view

becouse flow at nearest sprue is faster than other, although the distance from the branch to gate is

same, the flow of plastic will not good, nearest sprue will fill first and not same with another. Improved runner layout so we need another layout, below is improved runner layout for 6 product cavity, although is not the best, but it's more improved than first. but disadvantage of this runner layout is consume more material. Top view

3D view

Runner system, flowing part of plastic injection
After material injected by nozzle, runner systems will convey the molten material from the sprue to the gate. basic runner system consist of sprue, main runner, sub runner, cold slug, and gate.

since the design of the runner system has large effect on molding quality, molding efficiency, cycle time, cooling time and other factor, it is important key when design of mold. Runner System Construction Sprue sprue will contact first time with melt plastic, at the injection process, sprue always contact with nozzle from the injection machine, so consider when design the sprue consider the ball radius of nozzle, make sure it isn't make undercut on sprue.The dimensions of the sprue depend primarily on the dimensions of the molded part in particular the wall thickness, too little sprue will make sprue cold faster and make insufficient flow.

Main Runner First time when design runner system, determine number of cavities, shape and gate types, then arrange the cavity layout,at the multi cavity of mold balancing of runner is important, balancing ensures virtually equal flow of plastic trough each gate. To achieve balancing runner layout must be though, Sub Runner this part will continues flow from main runner until the gate, the dimension of sub runner and how much sub runner system will be, is very depending on how much cavity of the mold, and how the layout, what the layout use herring bone, H type, or star type. at the picture above use H type runner layout. Cold Slug when runner layout bent, clod slug may be required to continue plastic flow of better quality to the cavities.The cold slug well helps the flow of material through the runner system by stopping colder, higher viscosity material moving at the forefront of the molten mass entering into the

cavity.The length of the well is usually equal to or greater about 1,5-2 time than the runner diameter. Gate Basic purpose of the gate is to limit the flow of the melted plastic, but it must allow that melted plastic flow and fill the cavity easily. considering the fluidity of the material, gate should be made near the center of gravity of molding or the line to make flow uniform and melted material even, then make the gate thick but still considering melted plastic material, becouse thin part will cooled easily and faster. the gate type is very various depend on part shape, mold layout, mold system, etc, here some explanation about design those gate type: 1. Direct gate 2. Side, edge gate 3. Tab gate 4. film gate 5. fan gate 6. Disc gate Runner geometry they are various geometry that we can use in runner, such us 1. full round 2. half round 3. trapezoid use full round and trapezoid shape is recommended in various mold. Half round runners are not recommended because of their low volume to surface ratio here some area calculation of cross section of runner (source : http://www.dsm.com)

Runner dimensions The diameter of a runner depends on its length in addition to the part volume, part flow length, injection machine capacity, and gate size, Generally runner must never be smaller than the largest wall thickness of the product, it's usually make from 3 mm until 15 mm. picture below shown relation between runner diameter and maximum runner length (source : http://www.dsm.com)

The runner should be large enough to minimize pressure loss, yet small enough to maintain satisfactory cycle time, Large runners are not economical because of the amount of energy that goes into forming, and then regrinding the material that solidifies within them. Runner layout In general they are three type of runner layout 1. "H" bridge (branching) runner system 2. Standard (herringbone) runner system (conventional runner) 3. Radial (star) runner system look at picture below shown standard runner and H bridge type runner.

(Source: http://www.hotmold.cn) and below is star layout runner system (both bottom picture)

(sou rce : http://www.dsm.com) Balancing the runner system ensures that all mold cavities fill at the same rate and pressure, if the product have not similar product geometry, it is recommended to use mold analysis software like mold flow or C-Mold

Main Construction Pin at 3Plate Mold
I take those topic, to start learning about kind of pin on 3 Plate Molds, becouse between 3plate and 2 plate mold have several different function of Pin. Basically 3 Plate mold to support the main construction have 3 kind of Pin.Look at picture below

(click the picture to enlarge) 3 Part Pin are 1. Main Support Pin 2. Positioning Pin 3. Puller Bolts those pin will support both opening and closing process of 3 plate type of injection Mold. the function each pin are Main Support Pin this pin is totally support cavity, and runner plate when molds in open,when we buy mold base plate from fabricator, they always have exact diameter of Support Pin that we needed, it was calculated, but if your part is precision ensure it by calculating the deflection of those pin caused by cavity plate and runner plate. make sure the deflection of pin not larger than 0.1 mm, choose more large diameter of Support pin when deflection is large. Positioning Pin Because support pin doesn't precision when closing, we need more precision guide part, this part also named Guide Pin, becouse it will guide core and cavity matching together. use this part with the Bush, in high precision part, some times we need more than one Positioning Pin, we can also add block guide, taper block set, taper pin set and other high precision positioning tools. Puller Bolts

puller bolts doesn't support any plate, this part actually include in opening part of three plate molds. working together with tension link or magnet block, this part will make parting line at stripper plate and top plate, this parting line used to make sure that sprue was cut from nozzle. Parting line Opening is about 5-10 mm, depend on large of molds. look at picture below to learn the length of each Pin.

Sprue bush cooling design and construction
some times sprue bush need cooling to cut the cycle time of injection process, when diameter of sprue is large cooling in sprue bush is important. some fabrication of mold part have their own sprue bush that containing cooling pipe. like picture below

from those picture some standard part mold company have their own methods to make inner cooling at the sprue bush, we can by cutting in some part that weld together again, or by other method. the other way to make cooling in sprue is like picture below

by those type of sprue we change the entrance and exit flow by using stopper buffle, for example like picture below

or you can make the flow straight, the other cooling method in sprue is like picture below, by using this type is easy to attach the O ring, becouse in and out flow from below side that contact

with moldbase. becouse when assembling of ring to moldbase is more easy by attach the O ring in Moldbase then put the sprue bush than attach the O ring in sprue bush and assembling it together in moldbase.

Locating Ring Design and Construction in Injection Mold
Locating ring is simple part but, very important when mold base attach to injection machine, ok here the construction of locating ring after assembled in mold base.

then after attach in injection mold, the position of locating ring is like below

Basic Rule Design 1. when design locating ring, first rule is look at your injection machine catalog or hand book, and find the dimension of locating ring. like picture below from picture above we know that locating ring diameter is 200 mm and diameter of nozzle is 52 mm, so your locating ring outer diameter must same with those injection machine locating ring hole. 2. don't worry about the tolerance, at the injection machine tolerance always about minus 0.010.1 mm, then the locating ring tolerance if we buy in standard mold part company is about minus 0.01-0.05. 3D Modeling various Locating Ring below is some picture of locating ring that was i sketch using Google sketchUp, now i provide two type of locating ring. to choose right locating ring in mould is depend on injection machine nozzle, locating hole diameter, nozzle length in other factor.

Second type

Third type

this type have large chamfer from top to bottom in inner hole, those chamfer provide shape so nozzle can touch the sprue more precise and easier.

and below is sample picture of locating ring base on Mold Part Industries

Sprue Bush Design in Injection Mold
The molten plastic injected from the injector nozzle will go through a sprue (sprue bush), a runner, and a gate and fill up in the cavity. As the temperature of molten plastic is lowered while going through the sprue and runner, the viscosity will rise; therefore, the viscosity is lowered by shear heat generated when going through the gate to fill the cavity. so learn Sprue bush design is important, becouse sprue bush is part that contact first time with melted plastic, bad design of sprue bush can make plastic product broken, especially sprue broken and runner broken. picture below shown mold basic construction with sprue.

below is 3D model of sprue bush with 2 bolts

this type is commonly use in small mold size, until 350 ton injection machine is still used. the other construction is 4 bolts, this sprue bush type commonly use in large mold type and mass production, more than 200 ton

and below is sprue bush with ring attachment, this type use when top plate thickness is width, but some designer prefer use large chamfer in top plate so with first model sprue bush is still can be attach

Sprue Bush Design Rule 1. Ball radius of sprue must larger than ball radius nozzle, so don't forget to check diameter of nozzle of injection machine, or you can look at injection machine catalog. for example when ball radius of nozzle of injection machine is 10 mm use ball radius sprue bush 11 until 13 mm. 2. Hole diameter inner must be larger than hole diameter nozzle, diameter nozzle is variating base on machine injection type and manufacture, is about 2 mm until 5 mm. use 0.5 mm more larger than hole diameter of nozzle. 3. check your plate thickness, make sure that length of sprue bush fit with the plate thickness.

Other Joint Construction Betwen Cooling in cavity and Mold base with O Ring

What is O ring o-ring is a loop of elastomer with a round (o-shaped) cross-section used as a mechanical seal or gasket. They are designed to be seated in a groove and compressed during assembly between two or more parts, creating a seal at the interface. (wikipedia.com) O-Rings are torus-shaped (i.e. doughnut-shaped) objects made from elastomeric compounds such as natural or synthetic rubber, and are used to seal mechanical parts against fluid movement (air or liquid). O-Rings perform their sealing action by deforming to take the shape of their cavity, after being oversized to guarantee an predetermined interference fit.( efunda.com)

O ring typically used in one of two seal designs, axial or radial, in mold design to attaching cavity to mold base axial, face type are commonly used then radial type, because axial type is more easy to assembly in mold than radial type. 2D O ring drawing like picture below

Static seals exist where there is no relative motion between the mating surfaces being sealed.

at previous post about basic construction for joining cooling system in cavity and mold base , we can learn how to joint pipe from mold base of mold to cavity site. various construction can be develop from basic construction, previous post basic construction is fast and cheap construction model, but it isn't good when you in large mold and mass production mold, why? becouse production mold must have endurance until 1000 000 shot. Picture below shown develop construction of joining cooling pipe

blue color indicate mold base side and yellow color indicate cavity side. basic rule from those picture are : 1. T is height of O ring 2. part of O ring that will receive pressure form cavity plate. 15-30% from it's height is best. this little pressure give to prevent leak when water flow in cooling system. 3. t2 value is same with t, but t2 is horizontal, becouse O ring always made from elastomer plastic, by little pressure we can add O ring to O ring hole. 4. L is Gap between cooling channel and O ring hole. O-Ring Design Considerations 1. Proper Squeeze ‡Compression expressed as a percentage of the free-state cross-sectional thickness:

‡Face Seal: 20-30%

‡Static Male/Female: 18-25% ‡Reciprocating: 10-20% ‡Rotary: 0-10% 2. In static seals, where the O-Ring is not in axial motion in the bore, the recommended maximum compression is approximately 40%. 3. The O-Ring must be compressed by a predetermined amount, and this compression determines the O-Ring cross-section diameter. 4. The O-Ring inner diameter is typically chosen to be close to the groove's inner diameter; by selecting it to be slightly less than the groove's inner diameter, the O-Ring will stretch and hug the groove. 5. The Groove Width must be larger than the O-Ring cross-section diameter, to accommodate the radial expansion of the O-Ring when it's axially compressed in the gland. 6. stretch, - Excessive stretch can overstress material, thin cross section, and reduces % squeeze - % cross section reduction due to stretch about half of the % ID stretch 7. Sharp Corners, make R in cornet to prevent damage during seal installation. 8. Pressure and Clearance Gap. Most elastomeric seals are designed to operate within ambient pressure to about 1,500 psi. At very high pressures, the seal must have sufficient strength to resist extrusion into the clearance gap. The chart at right illustrates the recommended limits of the combination of clearance gap (diametral), seal hardness, and pressure differential. picture below shown graph between clearance gap and pressure

9. When it is said that an elastomer is good for an application it is meant that some compounds which include that material are acceptable. Not All. For instance, some compounds of EP are good for brake fluid applications, but most are not acceptable. 10. DO NOT use a lubricant composed of the same material as the O-ring. For example, a silicone lubricant should NOT be used with a silicone O-ring. 11. Avoid using graphite-loaded compounds with stainless steel, as they tend to pit the stainless steel surface over time. useful reference http://www.rlhudson.com/O-Ring%20Book/designing-static.html http://www.pspglobal.com/application-limits/04-watery-substances.html http://en.wikipedia.org/wiki/O-ring http://www.efunda.com/DesignStandards/oring/design_guidelines.cfm#axial http://www.marcorubber.com http://www.allorings.com/gland_static_axial.htm

Construction of Cavity Cooling and Mold Base Cooling, O ring
here the basic construction of joining cavity cooling and mold base cooling, we can use from simple construction to joint cavity and mold base cooling with one O ring, or we can use more complex construction like using special plate, and various O ring seal type. here is basic construction to joint the cavity cooling and mold base cooling.

both circular type and straight type cooling can be joint use those construction, those construction use in half circular type of cooling system like picture below

click the image to see more large simple joint just need one O ring or rubber seal, O ring pocket is preferred make in horizontal face from assembly, becouse it's make assembly and machining process mold more easily, basic rule and tolerance to prevent leak in O ring are like picture below

at the cross section of cavity and mold base cooling construction, blue color indicate mold base part, and light yellow indicate cavity block, green is indicate hole or pipe of cooling. light black is O ring before penetrate with cavity block. however is the simplest construction to join cooling cavity and mold base.

Straight Type Cooling for Cavity
Basically cavity system cooling can divide into two type 1. straight type 2. Circular type straight type system, usually have in and out of water pipe in not same side of mold or cavity. look at picture below

although the pipe that cool of insert part doesn't straight, but if inlet and outlet cooling fluid is not in same side we can consider that those type of cooling is straight. red color pipe indicate inlet and blue color pipe indicate outlet. second picture below is still same with previous but this picture include the cavity block

yellow part at each side is plug to prevent unwanted flow of cooling, pink block at the center is core insert part. with attach to core block using bolt. Block with blue color is core block before inserted to mold base.

Basic Functions of Mold Base Parts
A mold plate is any plate required to built a complete mold, in all plate use for molds have the main requirements, they are : 1. Good corrosion resistant 2. Good Machinability. 3. Easy to clean 3. Good heat transfer. 4. Homogeneity of steel. 5. Easy ability. 6. Low Cost. at picture below you can see 3 plate mold base type with closed position, basically 3 plate type and 2 plate type has some main plate, see explanation about mold construction type to understand more,

explanation below based on number at those picture 1. Fixed Clamping Plate or Top Plate Holds The fixed side of the mold to attached at the fixed platen of the injection machine. at this plate will attach locating ring, eye bolt, and sprue bush. 2. Runner Stripper Plate this plate only used in 3 plate molds type, the function is to cut resin from nozzle in top of sprue bush, and pull the runner by runner locking pin. 3. Fixed Mold Plate or Cavity plate. use to hold cavity side of product, leader pin, support pin, Puller bolts, and Angular pin when slider attached. 4. Movable Cavity Plate or Cavity plate it used to attach core side of product, return pin, leader bush and slider core if needed. 5. Back up Plate or Support plate used to support cavity plate, attach the hole for return pin's spring, and cooling channel when in cavity plate can not make it. 6. Spacer Block Mounted between the movable clamping plate (bottom plate) and the movable cavity plate to give space and allow the ejector plate to move when ejecting the part. the required length of spacer block depend on ejector stroke that needed to eject product. 7.Ejector retainer plate to hold the ejector, Z pin, shoulder bolts,and give space to ejector leader pin and support pillar. 8. Ejector Plate Pushes the ejector pins and return pins, connected with ejector rods. 9. Movable Clamping Plate or Bottom plate

Holds The movable side of the mold like spacer block, support plate, cavity plate and ejector mechanism to the movable platen of the injection machine.

and look at picture below, shown 3 plate molds type in opening position, but at picture below, Bottom plate or movable clamping plate is number 7, number 8 is ejector retainer plate, and number 9 is ejector plate.

Top Plate, Stripper Plate,Sprue Bush and Runner Lock Pin Design
at the picture below you will see a set of Top plate until stripper plate design related with runner flow, at this picture support pin exclude. the mold type in this picture is 3 plate type. the runner system accommodates the molten plastic material that coming from barrel, and guide it into mold cavity, the dimension, configuration, shape, and system connection with mold cavity will affect filling process.

as see from that picture, red plate indicate isolated plate, it's doesn't matter you use isolated plate or not, but you must see more in injection machine, if it needed isolated plate give it. number 1 and 2 in black plate it's indicated top plate for number 1 and stripper plate for number 2, those picture shown 3 open mold type. after injection, in ejection process stripper plate will open because puller bolt pull it( not include at those picture). runner ejector set will needed to push runner, after ejection, but if you use arm robot or manual take the runner by hand operator it doesn't needed. runner ejector set always contains spring, those spring will push pin in ejector set and will push the runner. runner lock pin function is to pull runner when ejection begin still in top plate, if runner adhere in stripper plate, the robots or operator will difficult to take the runner, because no ejection system for runner in stripper plate. when design the runner system and ejection system for runner in 3 plate type of mold you should use those mold accessories.

When we need slider parts in Mold Design
second previous post i have post about the slider parts and construction in complete mold base , then now i give a little brief when we need slider in mold design, basically we design mold from our customer, first is we must look the parts that we will make by plastic mold, look mare at the drawing so we can know about tolerance and critical point of parts, seconds is define the parting line, first parting line is between core and cavity parts, and after that if the parts have side form we must define slider parting line, look picture below

from those parts we know that we need slider parts, side hole and other shape that can not form by core and cavity became slider parts. below is picture in 3D modeling,look at the hole shape in side, those shape need slider part.

and how the construction of slider, more about construction mold you can see by clicking mold construction or molds parts in quick topic, basically here i give slider 3D modeling and parts name, those parts names i take from Misumi standard mold design

you can use this tutorial for education and others purpose but still write copyright from this site.

Slider Design and Basic Construction
picture below show slider basic construction in Mold, various construction and litle part available in slider but the basic construction of slider is same, look picture below, sorry if this picture is too grainy, i'll make a new one.

the main part from those picture is mold plate, number 1 until 10 is shown the plate of mold plate 1 is top plate plate 2 is gate opener plate, retainer plate, and others name depend in fabrics plate 3 is cavity plate plate 4 is core plate plate 5 is backing plate plate 6 is support plate plate 7 is ejector plate plate 8 is ejector retainer plate plate 9 is bottom plate plate 10 is runner plate and the slider part name are g for angular pin, this pin always have certain degree, usually between 10-30, angular pin will transfer vertical movement to horizontal movement, others construction, angular pin not from the top but from bottom, this kind of construction is rare to use now. h is slider core, when contact with angular pin, this part also the core from slider construction, at this part we can attach insert part that mold the shape of plastic. i is slider locking block, we can depend in angular pin when mold closed, slider pin is too week, so the holder of pressure from inside mold during injection process is locking block. k is slider lock plate, for non mass production you do not have to attach this part, but if the mold used in mass production, i suggest to use this part, because slider locking block and slider core always have friction, then when this part broken or got abrasive is will need expensive cost to

repair it, so use lock plate is better, is cheaper. l(L) is slider insert, this part which form the plastic product, it's attach in slider core

Mold part and construction
Many type of mold in the platic industry but generally mold devide in 3 big section there are : Two plate mold Two plate mold basically when opening the product after plastic injection process mold just devide in two parts core side and cavity side, this type molding only have one parting line, product parting line with located between core side and cavity side Look at picture below for more detail

Three plate mold Basically when product out after injection process this mold type divide in three parts, beside that, this type mold have three parting line, first between top plate and runner stripper plate, second are between stripper plate and cavity plate, the last is parting line product that located between core and cavity (see picture below)

hot runner mold (runner less mold) this type basically similar with two plate mold but not same, hot runner mold always heating the runner, so runner will not drop out with product, so it is some times called runner less mold, there is two big parts when opening after injection, core side and cavity side. Look at the picture below

Mold Construction look at the picture, the parts of mold are

1. Top plate (plate 1) 2. Striper plate (plate 2) 3. Runner plate (plate 10) 4. Cavity plate (plate 3) 5. Core plate (plate 4) 6. Spacer Block (plate 6) 7. Bottom plate (plate 9) 8. Ejector plate (plate 7) 9. Ejector retainer plate (plate 8)

Considering Factor that affecting gate size
when we design a gate for mold injection, we need a proper size of gate, to large size of gate will make unbalanced flow and defect in product. to small size of gate make cycle time high, unfil l of product and sink mark is appear easily in product. although there was various factor that affecting gate size, here i list some common factor that affecting gate size. Mass of Part of course large mass of part need more large gate size, i still doesn't have list a good relation graph or table which various material and mass of part. Herbert Ress in Mold Engineering 2nd edition page 159 listed some suggested dimension for gate cross section but it just very general list without material and other kind of gate. Size of Part

size of part also have large effect when we design a proper gate,longer flow length, larger cavity surface in injection mold of course need larger size of gate. Temperature of Melt when we use possible maximum temperature then cavity still cannot be filled, use more smaller gate, because with smaller gate more heat from heater can be transfered in resin, so shear stress of resin will decrease and viscosity also decrease, then resin will flow easily with small value of viscosity. Nozzle Tip Position don't use smaller length between nozzle tip and gate, because it will make freeze premature, if the construction of mold does not enable to make longer length, you can prevent that by making the gate more smaller. Viscosity of Resin viscosity of resin and shear stress of resin have large effect in proper gate designing. if we buy a resin, shear stress and viscosity data also available, use those data to calculate proper gate size. we can calculate average plastic flow by dividing shear volume with injection time. always use average plastic flow speed more than speed of sound, more than 340 m/s, if your value below the speed of sound it large possibilities that your product will shot (unfinish fill of product). although other factor beside i write above there are some large factor like cooling speed, cooling temperature and injection time also have valuable effect when designing the gate, the main point was i write all above. from those main point i think we should design a proper gate in mold fast and effective.

Pin Point Gate Construction
pin point gate is commonly used in 3 plate mold types, see explanation more about 3 plate more here, basically the pin point gate part is like picture below

those picture is pin point gate picture, to make gate like that we can buy pin point gate bush in mold manufacture company or we make it by EDM (electronic Discharge Machine) Process, the special EDM torch for Pin Point gate also available in mold part markets. Pin Point gate Bush picture below shown simple pin point gate bush,

the construction to assembly the pin point gate bush in mold is like picture below straight, without extended bush, picture below shown, locating ring, pin point gate bush, runner lock pin, runner, product and mold base plate (top plate, stripper plate and cavity plate)

some times, we need extended pin point gate bush, why when plastic material have high shear

rate, we need to assembly extended bush, so from diameter gate until runner plastic material will easy to flow the cavity. see the construction at picture below

here some good link of standard component of gate, http://www.misumieurope.com/www/lang/catmold_eng/nav/006/hl/007/menu/catalogues/fn/21/content.html

Diaphragm Gate Design in Thermoplastic Mold
Actually this gate is another variation of side gate, but this gate have circumferential shape like fan gate,some time it also named as disc gate. basic modeling of diaphragms gate is like the picture below

this type applied when at the center of product has a trough hole, plastic flow when injections is similar to direct gate, but flow plastic material more constant and controlled becouse this gate have circular flat thickness. this gate punched out after ejection. Design and Size the following picture below shown basic part and size of diaphragm gate.

The gate height (t) is preferred about 0.1mm -0.17 mm The circular runner height (T) is recommended about 5-10 mm depend on your size of product. Land size (D-d) is about 1mm-5 mm each side.

Design Gate sumary from hanser book
embed object below taken from ipaper, at the text book below will explain clearly how to design a good gate in plastic mold, to view more large click a little arrow at the top right, after click choose plus mark to see more large.

6 Design of Gates
6.1 The Sprue Gate
The sprue gate is the simplest and oldest kind of gate. It has a circular cross-section, is slightly tapered, and merges with its largest cross-section into the part. The sprue gate should always be placed at the thickest section of the molded part. Provided proper size, the holding pressure can thus remain effective during the entire time the molded part solidifies, and the volume contraction during cooling is compensated by additional material forced into the cavity. No formation of voids or sink marks can occur. The diameter of the sprue gate depends on the location at the molded part. It has to be a little larger than the section thickness of the molded part so that the melt in the sprue solidifies last. The following holds (Figure 5.9): dF S max + 1.0 (mm). (6.1) It should not be thicker, though, because it then the melt solidifies too late and extends the cooling time unnecessarily. To demold the sprue without trouble it should taper off towards the orifice on the side of the nozzle. The taper is 1±4°. (6.2) American standard sprue bushings have a uniform taper of 1/2 inch per foot, which is equivalent to about 2.4°. The orifice towards the nozzle has to be wider than the corresponding orifice of the nozzle. Therefore dA dD + 1.5 mm (6.3) (Refer to Figure 5.9 for explanation of symbols) If these requirements are not met, undercuts at the upper end are formed (Figure 5.8). Very long sprues, that is if the mold platens are very thick, call for a check on the taper. Possibly another nozzle has to be used in the injection molding machine.

To a large degree the release properties of the sprue also depend on the surface finish of the tapered hole. Scores from grinding or finishing perpendicular to the direction of demolding have to be avoided by all means. Material would stick in such scores and prevent the demolding. As a rule the interior of sprue bushings is highly polished. A radius r2 (Figure 5.9) at the base of the sprue is recommended to create a sharp notch between sprue and molding and to permit the material to swell into the mold during injection. To its disadvantage, the sprue always has to be machined off. Even with the most careful postoperation, this spot remains visible. This is annoying in some cases, and one could try to position the sprue at a location that will be covered after assembly of the article. Since this is often impractical, the sprue can be provided with a turnaround so

2066 Design of Gates

that it reaches the molded part from the inside or at a point not noticeable later on (Figure 6.1). The additional advantage of such redirected sprues is the prevention of jetting. The material hits the opposite wall first and begins to fill the cavity from there [6.2]. Machining as a way of sprue removal is also needed here. Another interesting variant of a sprue gate is shown in Figure 6.2 It is a curved sprue, which permits lateral gating of the part. It is used to achieve a balanced position of the molded part in the mold, which is now loaded in the center. This is only possible, how- ever, for certain materials, such as thermoplastic elastomers.

6.2 The Edge or Fan Gate
An edge gate is primarily used for molding parts with large surfaces and thin walls. It has the following advantages:
Figure 6.2Curved sprue [6.3] Figure 6.1Sprue with turnaround [6.1] (also called ³overlap gate´)

207
6.2 The Edge or Fan Gate

± parallel orientation across the whole width (important for optical parts), ± in each case uniform shrinkage in the direction of flow and transverse (important for crystalline materials), ± no inconvenient gate mark on the surface. The material leaving the sprue first enters an extended distributor channel, which connects the cavity through a narrow land with the runner system (Figure 6.3). The narrow cross-section of the land acts as a throttle during mold filling. Thus, the channel is filled with melt before the material can enter the cavity through the land. Such a throttle has to be modified in its width if the viscosity changes considerably.

The distributor channel has usually a circular cross-section. The relationship of Figure 6.3 generally determines its dimensions. They are comparable with the corresponding dimensions of a ring gate, of which it may be considered a variant. Besides the circular channel, a fishtail-shaped channel is sometimes met (Figure 6.4). This shape requires more work and consumes more material, but it results in excellent part quality due to a parallel flow of the plastic into the cavity. Dimensioning was mostly done empirically so far. Today it can be accomplished with the help of rheological software packages such as CADMOULD, MOLDFLOW, etc. (see Chapter 14).
Figure 6.3Edge gate with circular distributor channel [6.1, 6.4] D = s to 4/3 s + k, k = 2 mm for short flow lengths and thick sections, k = 4 mm for long flow lengths and thin sections, L = (0.5 to 2.0) mm, H = (0.2 to 0.7) s. Figure 6.4Edge gate with adjusted cross section resulting in uniform speed of flow front [6.5]

How to design fan gate in thermoplastic injection mold
fan gate, is a gate spreading toward in to cavity, basically this gate is thin similarly with previous gate (film gate) and is used in same purpose with film gate. with the gate construction it permits rapid filling of large parts or fragile section mold area with large entry area. it is used to create uniform flow into wide parts. Purpose 1. thereby keeping the cross sectional area constant. 2. This ensures a constant and more even plastic flow into the cavity into a wide area at a slow injection speed, minimizing backfilling and reducing imperfections and stresses in the part. 3. used for thick-sectioned moldings and enables slow injection without freeze-off. 4. favored for low stress moldings or where warpage and dimensional stability are main concerns. 5.The melt velocity will be constant. 6.The entire width is being used for the flow. 7. The pressure is the same across the entire width Construction and Design

side View

The gate should taper in both width and thickness, to maintain a constant cross sectional area, although at picture below thickness is doesn't tapered.

Dimension

the land thickness can be vary thin relative to the part thickness because the gate is very wide.the maximum thickness should be no more than 80% of the part thickness. if the parts very thin like 0,8 mm, you can also use 0.7 mm fan gate thickness, but when rubber is used as material parts, use 100 % of the thickness parts is more easy to control flow and product quality. The gate width varies typically from 6 mm up to 25% of the cavity length.in large parts is often use fan gate as wide as the parts it self. Simulation Picture all picture below based on injection simulation process, using material PS ASAHIPS 693 : Asahi Chemical other data are ==== Machine setup ==== Melt temperature = 503.15 K Mold temperature = 323.15 K Fill time = 0.08 s Packing/Holding time = 4.24 s Cooling time = 7.72 s Packing/Holding pressure = 12627300.00 Pa ==== Machine specification ==== Required clamp force = 27647.70 N Required shot size (GPS) = 0.01 kg Simulation results mold time filling in seconds

time to cool after injection from below picture we can learn where is the best position to make cooling layout, after you make cooling layout, enter the cooling simulation process to your parts. if the distribution is same in all shape of part (unless runner and gate) your design is good to realize.

Pressure distribution

all picture is enabled to enlarge, click the picture to enlarge.

Film Gate Design (flash gate)
Film gate also called flash gate is very thin compare to another gate, this thin gate like film which have parallel runner before the gate, this type of gate used for straight edges. picture below shown film gate with main parts.

in generally this gate used in thin and flat requirement, like flat mobile phone cap, ipod cap and others. but sometimes this gate is not likely going to have a flat flow front, the make flow material more stable and flat, make temperature molds more higher than usual, but cycle time will also higher. here is film gate from top view

Dimension recommended dimension is approximately 0.2 mm to 0.6 mm in thick, the land area (parallel runner) is also be kept small approximately 0.6 mm - 1 mm depend the large and weight of product. Other Design picture below shown other design of film gate, with more reliable and easy in process.

look the different model of film gate, and different design of parallel runner. picture below shown simulation of plastic flow from those design

and the last picture shown time that needed to cooling the melt plastic in mold

from the picture above we can choose the right place to make cooling pipe, the red color marks mean need more time to cool the product.

Tab gate design in Mold

general construction of tab can see at picture below

basically melted material is fed to this gate from a separate primary gate (after runner), the function of the gate typically is employed for flat and thin parts to reduce the shear stress in the cavity, Tab gate able to used in various material plastic such us ABS, PS, acrylic, PP, PVC, Polycarbonate. SAN and other which has relatively low fluidity. at this type of gate, the high shear stress generated around the gate that trimmed after molded. this gate sometimes also called the collision gate. Function in Product and General Rule The thickness of tab gate should be the same as the part wall, yo can also make more thin, but when designed parts for cosmetic parts if preferred that the thickness is same with the product thickness. rule number two is, make the gate as center as possible in the product side, but you must consider the product size and shape. basically minimum tab width is about 6,5 mm and the tab thickness minimum is 75 % from the thickness product

for more picture and drawing view,please look at picture below

(Top View of Tab Gate)

(Front view of Tab Gate)

(Side View of Tab Gate) each picture is able to enlarge by clicking the picture.

side gate, edge dimension design
edge gate is the simplest type of gate and is used wherever the product can or must be gated from parting line. it's designed commonly for injection machine attended by operator, because the product must separated from the runner system by hand with the aid of side cutter. Dimension Picture below shown ideal configuration and practical gate, suggested dimension for general application of edge or side gate are

Runner width and Height for side gate or edge gate is preferred that height is about 0,7-0,8 from width of runner. the width of runner very depending on product size and weight, it from 3 mm until 7 mm in width ( product mass until 200 gram in maximum). Gate width and height is about W=3h,with W is width and h is height (look at Herbert Rees, Mold Engineering, pg 159) but this rule can't applied for all part or product form, specially for thick product that have large in width such us panel and cover, when design the dimension of gate take the rule that height of gate is must about 75 % from the parts thickness, Suggested take 0,6 until 0, 7 from parts thickness, but specially for elastomer material take more large about 8090 % from parts thickness. T is gate width, for product mass until 200 gr, suggested take 1 until 5 mm in width , for the very large product some times have width until 12 mm. C is Land of gate from runner, the length is should be no more than 1,5 mm. also preferred make taper before gate land, in that picture taper are change with R in both side, make R, taper or not is depend on side gate size and form.

Picture 1.A

Picture 1.B both those picture shown edge gate or side gate with different design, application, parting line, taper and R system. taper from bottom runner to gate land have various dimension, the taper in picture 1A is enough large, about 30-45 degree, in picture 1B taper is about 10-20 degree.

beside those type of side gate, they are still various type of side gate or edge gate, will upload in other post.

Side gate, edge gate design
as we know Gate In injection molding, is the channel through which the molten resin flows from the runner into the cavity. Generally, it is small and solidifies first. The restricted opening through which the plastic enters the mold cavity. Standard Gate this type of gate have various name, the common name are standard gate, edge gate and side gate, this is the most typical gate in molds, which is applied to almost all types of plastics. look at picture below, it's single side gate from sprue until gate and product (click the picture to enlarge)

how about the parting line? the are about 3 methods that we can choose when design parting line, 1. core side process,this type of parting line only core side that's must be machined , picture below shown side gate design with flat parting line in core side process. this type parting line is useful applied in product without taper in side of product, but when product have taper in side (like picture below) it will undercut and need slider to form the side of product.

2. cavity side process, this type of gate design parting line is one method to hide the marks of gate after injection process. at this type runner channel machined in cavity side, then a little gate machined at core side. this type of gate parting line is more good and more cheap than number

one when product have taper like picture below.

3. cavity and core side parting line, this type parting line for gate and runner is not common to use, when use this type parting line runner and gate, you must use cylindrical type of runner of semi cylindrical type of runner.

Direct Gate or Sprue Gate
What is Gate ? The entrance through which molten plastic flows into the cavity of the mold from the runner. This is where the flow or melting of molten plastic is controlled by control type of gate or gate dimension. It is positioned at the thickest area of a part. other function of gate is the gate makes it easier for the runner, which will be unnecessary after molding, to be separated from the part.is recommended to consider gating options early in part design. Direct Gate direct gate or sprue gate we can define as connecting directly end sprue to the molding and used as a gate, this type of gate is commonly used for single cavity molds, where sprue feeds the material to cavity molds directly rapidly with minimum pressure drop.

this type of gate is applied to molding of boxes or cups like bathtub, plastic bucket, and others, particularly large sized products. like at the picture above, shown cups product with direct gate before cutting. Dimensions and Construction from picture below we can concluded that direct gate is very easy to design,

from picture above the construction of direct gate is one parts with the product, after injection process, the sprue will cut manually. parting line between cavity and core can directly placed at top surface of product or more lower from top surface product, it very depending of product shape and characteristics.

starting sprue diameter is controlled by nozzle of injection

- then, make sure the diameter of sprue orifices must be larger than nozzle exit diameter, choose from 1-2 mm or about 1/32 inch. - give taper at the sprue from orifice diameter to product about 1-3 degree, it is will made the product demolded from cavity side more easy. - in general the diameter of the gate much greater than the thickness of the product. Advantages - Low cost of design. - The injection pressure was reduced due to direct cavity filling. - Simple way to design gate and runner system. - easy design and maintenance. Disadvantages some disadvantage of direct sprue are: - since excessive stress is left easily around the gate, cracking often starts around the gate. - when using non standard sprue tapers, will more expensive with little gain. - gate mark left on part surface after runner of sprue trimmed of. - This gate type can only produce one part per shot. - The gate has to be cut manually by a cutter. - Not applicable in little size product.

Sprue bush cooling design and construction
some times sprue bush need cooling to cut the cycle time of injection process, when diameter of sprue is large cooling in sprue bush is important. some fabrication of mold part have their own sprue bush that containing cooling pipe. like picture below

from those picture some standard part mold company have their own methods to make inner cooling at the sprue bush, we can by cutting in some part that weld together again, or by other method. the other way to make cooling in sprue is like picture below

by those type of sprue we change the entrance and exit flow by using stopper buffle, for example like picture below

or you can make the flow straight, the other cooling method in sprue is like picture below, by using this type is easy to attach the O ring, becouse in and out flow from below side that contact

with moldbase. becouse when assembling of ring to moldbase is more easy by attach the O ring in Moldbase then put the sprue bush than attach the O ring in sprue bush and assembling it together in moldbase.

Construction of Cavity Cooling and Mold Base Cooling, O ring
here the basic construction of joining cavity cooling and mold base cooling, we can use from simple construction to joint cavity and mold base cooling with one O ring, or we can use more complex construction like using special plate, and various O ring seal type. here is basic construction to joint the cavity cooling and mold base cooling.

both circular type and straight type cooling can be joint use those construction, those construction use in half circular type of cooling system like picture below

click the image to see more large simple joint just need one O ring or rubber seal, O ring pocket is preferred make in horizontal face from assembly, becouse it's make assembly and machining process mold more easily, basic rule and tolerance to prevent leak in O ring are like picture below

at the cross section of cavity and mold base cooling construction, blue color indicate mold base part, and light yellow indicate cavity block, green is indicate hole or pipe of cooling. light black is O ring before penetrate with cavity block. however is the simplest construction to join cooling cavity and mold base.

Straight Type Cooling for Cavity
Basically cavity system cooling can divide into two type 1. straight type 2. Circular type straight type system, usually have in and out of water pipe in not same side of mold or cavity. look at picture below

although the pipe that cool of insert part doesn't straight, but if inlet and outlet cooling fluid is not in same side we can consider that those type of cooling is straight. red color pipe indicate inlet and blue color pipe indicate outlet. second picture below is still same with previous but this picture include the cavity block

yellow part at each side is plug to prevent unwanted flow of cooling, pink block at the center is core insert part. with attach to core block using bolt. Block with blue color is core block before inserted to mold base.

Paralel and series Cooling methode at flat type plate of Mold Base
almost mold designer know that cooling is biggest part that effect cycle time of injection mold, a good design in cooling will make heat exchange between resin after injected and mold will reduce cycle time and give good product. at flat type of mold base plate like stripper (Plate number2) plate between top plate and cavity plate, top plate it self, and support plate after core plate, at the top plate cooling not always used, it very depend on resin type,and product shape. the picture below shown some flat mold base that we can use parallel or series cooling methods

How about core and cavity of Mold base ? we can use both type of cooling series and parallel when design cooling at core and cavity plate, but you must careful place the cooling, because beside cavity molds it self, they are ejector at the

core plate then sprue and runner system at cavity plate. the construction and how to connecting cooling at mold plate with cavity mold cooling will discuss later. Parallel Cooling Channel picture below shown parallel cooling channels concept

basic mold base cooling have four parts, they are : 1. Main Cooling pipe commonly cooling pipe make by drilling using bore,the longer drilled hole, it recommended have length about 6 mm if using long nipple joint to connect with outer tube, if using nipple or

inner joint plug each cooling pipe minimum have 12 mm. 2. stopper plugs, like at slider cooling and cavity cooling stopper plugs is prevent water or oil coolant flow to undesirable way. 3. Inner stopper plugs, the function is same as stopper plugs, but assembly methods and location is different, it assembled at inner of cooling pipe. parallel cooling channels are drilled straight trough supply manifold cooling pipe, due the parallel design flow characteristics, the flow rate along various cooling will different, because each cooling pipe have their own flow resistance. as a results, cooling of the mold will not uniform. so it's clear that parallel circuit of cooling in molds are very poor flow rates. Series Cooling picture below shown basic series cooling construction and methods

the parts is same with parallel cooling type, but the construction is different, at the series cooling channel types, it connected in single loop from the coolant inlet until its outlet, we can configure the flow by adjust the inner stopper plug type. when design it is recommended to use same size of diameter cooling, because it's can maintain the turbulent flow, turbulent flow enables heat to be transferred more effectively. Long and Shorts Nipple joint plug Assembly methods considering mold base material strength,closer distance between two nipple plug type are not advisable, look at picture below

assembly between long type and shorts type is different, by using long type minimum length from both side is 6 mm, except for little diameter hole, less then 5 mm, smaller length spacing my be acceptable. Short nipple joint types almost assembly in inner mold base, because of that minimum length space is 12,5 mm, although 10 mm my acceptable but will difficult to assembly it using hand.

Cavity mold cooling construction design
In commonly mold designer know that Cooling conditions affect cycle time, part dimensions, surface finish, and warpage. but some junior mold designer still confuse to make layout and construction of cooling in mold. before this posting, i havepost about cooling construction in slider, beside slider mold cavity also important to fill cooling, why because almost product 70-80 % is molded shape in mold cavity.

picture above shown core side of cavity mold, the basic construction is 1. Plug (Plug is for prevent water flow out from desire flow layout) 2. cooling pipe (as those picture cooling pipe doesn't shown, almost cavity cooling pipe processing using jig bor to make a long hole that becoming cooling pipe) 3. In / Out Hole, it's hole also make using jig bore. this hole will attach in cavity plat that will match with cooling layout in mold base. orange color indicate product insert hole shape. here i post basic construction in single cavity, see picture below to learn more

picture above is shown flow of cooling process of cavity mold from top view. then which hole water flow in and flow out, see picture below

at this wireframe method picture, we should make hole at bottom side of core to connected cavity and cooling layout of mold base. Tips Design Cooling pipe for cavity 1. make sure side of cooling pipe have enough length from insert, minimum 3 cm 2. choose a good diameter for the hole, like 6 cm, 8 cm, or 10 cm.

3. when injection proses begin make sure using calculation so you have turbulent flow in cooling pipe. 4. make the pipe more long is useful for make turbulent flow.

then how the layout and construction of cooling in mold base ? just wait for new post

Mold Cooling Design at Slider
Why mold need cooling ? as we know that cooling conditions affect cycle time, part dimensions, surface finish, and warpage, Mold cooling time is the biggest contributor to the overall cycle time, it could be as two-thirds or 70-80% of total cycle time. from those reason design an efficient cooling circuit can reduces the cooling time, beside that uniform cooling improve part quality by reducing residual stress, stability of heat transfer, and accuracies of part after cooled. Why Slider Need Cooling? Some product have long dimension that need slider, to prevent warpage, residual stress, and stability of shrinkage behavior, for that reason slider need cooling. Mold Cooling Construction picture below shown cooling construction at slider insert from top side.

annotation number at picture upper indicate part of slider, they are 1. Plug 2. Slider Insert 3. Cooling Pipe 4. Guide Rel of slider core 5. Locking Block slider 6. Long Nipple Pipe with blue color indicate flow of water when cooling process working. number 1 part (Plug) prevent water flow to side of slider inserts. When design nipple,make sure that nipple is long enough to reach outer side of mold base. to get understand more look at picture below, at this picture still shown cooling at slider from left side.

additional number of slider parts are 7. slider core (this part is one of slider main part, where slider insert attached) 8. Angular slider ( the main function of angular is change the moving 90 degree, so slider can move)

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