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Rapid ToolingRapid Tooling

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RAPID TOOLINGRAPID TOOLING

Rapid Tooling refers to Rapid Tooling refers to mould cavities mould cavities that are either directly or indirectly that are either directly or indirectly fabricated using Rapid fabricated using Rapid Prototyping techniques.Prototyping techniques.

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Soft Tooling:Soft Tooling:

It can be used to intake It can be used to intake multiple wax or multiple wax or plastic parts using conventional plastic parts using conventional injection moulding techniques. injection moulding techniques. It It produces short term production patterns. produces short term production patterns. Injected wax patterns Injected wax patterns can be used to can be used to produce castings. Soft tools can usually be produce castings. Soft tools can usually be fabricated for ten times less than a machine fabricated for ten times less than a machine tool.tool.

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Hard Tooling:Hard Tooling:

Patterns are fabricated by machining either Patterns are fabricated by machining either tool steel or aluminum into the negative tool steel or aluminum into the negative shape of the desired component. Steel shape of the desired component. Steel tools tools are very are very expensiveexpensive yet typically last yet typically last indefinitely building millions of parts in a indefinitely building millions of parts in a mass production environment. Aluminum mass production environment. Aluminum tools are less expensive than steel and are tools are less expensive than steel and are used for lower production quantities.used for lower production quantities.

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Indirect Rapid Tooling:Indirect Rapid Tooling:

As RP is becoming more mature, As RP is becoming more mature, material properties, accuracy, cost material properties, accuracy, cost and lead time are improving and lead time are improving to to permitting to be employed for production permitting to be employed for production of tools. Indirect RT methods are called of tools. Indirect RT methods are called indirect because they use RP pattern indirect because they use RP pattern obtained by appropriate RP technique as obtained by appropriate RP technique as a a model for mould and die makingmodel for mould and die making..

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Role of Indirect methods Role of Indirect methods in tool production:in tool production:

RP technologies offer the capabilities of RP technologies offer the capabilities of rapid production of 3D solid objects rapid production of 3D solid objects directly from CAD. Instead of several directly from CAD. Instead of several weeks, weeks, a prototype can be completed a prototype can be completed in a few days or even a few hours. in a few days or even a few hours.

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Unfortunately with RP techniques, there is Unfortunately with RP techniques, there is only a only a limited range of materialslimited range of materials from from which prototypes can be made. which prototypes can be made. Consequently although Consequently although visualization and visualization and dimensional verification are possibledimensional verification are possible, , functional testing functional testing of prototypes often is of prototypes often is not not possible possible due to different mechanical and due to different mechanical and thermal properties of prototype compared to thermal properties of prototype compared to production part.production part.

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All this leads to the next step which is for All this leads to the next step which is for RP industry to target tooling as a natural RP industry to target tooling as a natural way to capitalize on 3D CAD modeling way to capitalize on 3D CAD modeling and RP technology. With increase in and RP technology. With increase in accuracyaccuracy of RP techniques, numerous of RP techniques, numerous processes have been developed for processes have been developed for producing producing tooling tooling from RP masters.from RP masters.

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The most widely used indirect RT The most widely used indirect RT methods are to use RP masters to make methods are to use RP masters to make silicon room temperature vulcanizing silicon room temperature vulcanizing moulds moulds for plastic parts and as sacrificial for plastic parts and as sacrificial models or investment casting of metal models or investment casting of metal parts. These processes are usually parts. These processes are usually known as known as Soft Tooling TechniquesSoft Tooling Techniques..

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Silicon Rubber Tooling:Silicon Rubber Tooling:

It is a soft tooling technique. It is a indirect It is a soft tooling technique. It is a indirect rapid tooling method.rapid tooling method.

Another root for soft tooling is to use Another root for soft tooling is to use RP RP modelmodel as a as a patternpattern for silicon rubber for silicon rubber mould which can then in turn be injected mould which can then in turn be injected several times. several times. Room Temperature Room Temperature Vulcanization SiliconesVulcanization Silicones are preferable as are preferable as they do not require special curing they do not require special curing equipment. equipment.

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This rubber moulding technique is a This rubber moulding technique is a flexible mould that can be peeled away flexible mould that can be peeled away from more implicate patterns as suppose from more implicate patterns as suppose to former mould materials. to former mould materials.

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First an RP process is used to fabricate First an RP process is used to fabricate the pattern.the pattern.

Next the pattern is fixed into a holding Next the pattern is fixed into a holding cell or box and coated with a special cell or box and coated with a special release agent (a wax based cerosal or a release agent (a wax based cerosal or a petroleum jelly mixture) to prevent it from petroleum jelly mixture) to prevent it from sticking to the silicon.sticking to the silicon.

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The silicon rubber typically in a The silicon rubber typically in a two part two part mix is then blended,mix is then blended, vacuumed to remove vacuumed to remove air packets and poured into the box around air packets and poured into the box around the pattern until the pattern is completely the pattern until the pattern is completely encapsulated. encapsulated.

After the rubber is fully cured which usually After the rubber is fully cured which usually takes takes 12 to 24 hours12 to 24 hours the box is removed the box is removed and the mould is cut into two (not and the mould is cut into two (not necessarily in halves) along a pre necessarily in halves) along a pre determined parting line. determined parting line.

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At this point, the At this point, the original pattern is pulled original pattern is pulled from the silicon mould from the silicon mould which can be which can be placed back together and repeatedly filled placed back together and repeatedly filled with with hot wax or plastichot wax or plastic to fabricate multiple to fabricate multiple patterns. patterns.

These tools are generally not injected due to These tools are generally not injected due to the soft nature of the material. Therefore the the soft nature of the material. Therefore the final part materials must be poured into the final part materials must be poured into the mould each cycle.mould each cycle.

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Wire Arc Spray:Wire Arc Spray:

These are the thermal metal deposition These are the thermal metal deposition techniques such as techniques such as wire arc spray wire arc spray and and vacuum plasma depositionvacuum plasma deposition. These are . These are been developed to coat been developed to coat low temperature low temperature substratessubstrates with with metallic materialsmetallic materials. This . This results in a range of low cost tools that results in a range of low cost tools that can provide varying degrees of durability can provide varying degrees of durability under injection pressures.under injection pressures.

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The concept is to first deploy a The concept is to first deploy a high high temperature, high hardness shell temperature, high hardness shell material material to an RP pattern and then backfill to an RP pattern and then backfill the remainder of the two shell with the remainder of the two shell with inexpensive low strength, low inexpensive low strength, low temperature materialstemperature materials on tooling on tooling channels. channels.

This provides a This provides a hard durable facehard durable face that that will endure the forces on temperature of will endure the forces on temperature of injection moulding and a soft banking that injection moulding and a soft banking that can be worked for optimal thermal can be worked for optimal thermal conductivity and heat transfer from the conductivity and heat transfer from the body.body. 1616

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In Wire Arc Spray, the metal to be deposited In Wire Arc Spray, the metal to be deposited comes in filament form. Two filaments are comes in filament form. Two filaments are fed into the device, one is positively charged fed into the device, one is positively charged and the other is negatively charged until they and the other is negatively charged until they meet and create an electric arc. meet and create an electric arc.

This arc melts the metal filaments while This arc melts the metal filaments while simultaneously a high velocity gas flows simultaneously a high velocity gas flows through the arc zone and propels the through the arc zone and propels the atomized metal particles on to the RP atomized metal particles on to the RP pattern.pattern.

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The spray pattern is either controlled The spray pattern is either controlled manually or automatically by robotic manually or automatically by robotic controlcontrol. Metal can be applied in successive . Metal can be applied in successive thin coats to very low temperature of RP thin coats to very low temperature of RP patterns without deformation of geometry. patterns without deformation of geometry.

Current wire arc technologies are limited to Current wire arc technologies are limited to low temperature materials, however as well low temperature materials, however as well as to metals available in filament form.as to metals available in filament form.

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Vacuum Plasma Spray technologies are Vacuum Plasma Spray technologies are more suited in more suited in higher melting temperature higher melting temperature metalsmetals. The deposition material in this case . The deposition material in this case comes in comes in powder form powder form which is then which is then melted, accelerated and deposited by melted, accelerated and deposited by plasma generated under vacuum.plasma generated under vacuum.

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3D Keltool Process:3D Keltool Process:

This process is based on metal sintering This process is based on metal sintering process. This process converts RP process. This process converts RP master patterns into production tool master patterns into production tool inserts with very inserts with very good definition and good definition and surface finish. surface finish.

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The production of inserts including the The production of inserts including the 3D Keltool process involves the following 3D Keltool process involves the following steps.steps.

Fabricating the master patterns of core Fabricating the master patterns of core and cavity.and cavity.

Producing RTV silicon rubber mould from Producing RTV silicon rubber mould from the pattern.the pattern.

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Filling the silicon rubber mould with Filling the silicon rubber mould with metal mixtures metal mixtures to produce to produce green parts green parts duplicating the mastersduplicating the masters. Metal mixture . Metal mixture is is powdered steel, tungsten carbide powdered steel, tungsten carbide and polymer binder with particle and polymer binder with particle sizes of around 5 nmsizes of around 5 nm. Green parts are . Green parts are powdered metal held together by powdered metal held together by polymer binder.polymer binder.

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FiringFiring the green parts in a furnace to the green parts in a furnace to remove the plastic binder and remove the plastic binder and sintering sintering the metal particles together.the metal particles together.

InfiltratingInfiltrating the sintered parts (70% the sintered parts (70% dense inserts) with copper in the second dense inserts) with copper in the second furnace cycle to fill the 30% void space.furnace cycle to fill the 30% void space.

Finishing the core and cavity.Finishing the core and cavity.

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3D Keltool inserts can be built in two 3D Keltool inserts can be built in two materials. Sterlite of A6 composite tool materials. Sterlite of A6 composite tool steel. The material properties allow the steel. The material properties allow the inserts using this process to withstand inserts using this process to withstand more than 10lakh mould cycles.more than 10lakh mould cycles.

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Epoxy ToolsEpoxy Tools

Epoxy tools are used to manufacture Epoxy tools are used to manufacture prototype parts or prototype parts or limited runslimited runs of of production parts.production parts.

Epoxy tools are used as:-Epoxy tools are used as:- Moulds for prototype injection plasticMoulds for prototype injection plastic Moulds for castingMoulds for casting Compression mouldsCompression moulds Reaction Injection MouldsReaction Injection Moulds

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The fabrication of moulds begins with the The fabrication of moulds begins with the construction of a construction of a simple frame around simple frame around the parting line of RP modelthe parting line of RP model. .

Sprue, gates and runners Sprue, gates and runners can be added can be added or cut later on once the mould is finished. or cut later on once the mould is finished. The exposed surface of the model is The exposed surface of the model is coated with a coated with a release agent and epoxy release agent and epoxy is poured over the model. is poured over the model.

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Aluminum powderAluminum powder is usually added to is usually added to epoxy resin and epoxy resin and copper cooling lines copper cooling lines can also be placed at this stage to can also be placed at this stage to increase the thermal conductivity of the increase the thermal conductivity of the mould.mould.

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Once the epoxy is Once the epoxy is curedcured the the assembly is assembly is invertedinverted and the parting line block is and the parting line block is removed leaving the pattern embedded in removed leaving the pattern embedded in the side of the tool just cast.the side of the tool just cast.

Another frame is constructed and epoxy is Another frame is constructed and epoxy is poured to form the other side of the tool. poured to form the other side of the tool.

Then the second side of the tool is cured. Then the second side of the tool is cured. The two halves of the tool are separated The two halves of the tool are separated and the pattern is removed. and the pattern is removed.

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Another approach known as Another approach known as soft surface soft surface rapid toolrapid tool involves machining an involves machining an oversized cavity in an Aluminum plate. oversized cavity in an Aluminum plate.

The offset allows for introduction of The offset allows for introduction of casting material which may be poured casting material which may be poured into the cavity after suspending the into the cavity after suspending the model in its desired position and model in its desired position and orientation. orientation.

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Some Some machiningmachining is required for this is required for this method and this can method and this can increase the mould increase the mould building timebuilding time but the advantage is that but the advantage is that the the thermal conductivity is better thermal conductivity is better than than for all epoxy models.for all epoxy models.

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Unfortunately Unfortunately epoxy curingepoxy curing is an is an exothermic reactionexothermic reaction and it is not always and it is not always possible directly to cast epoxy around a possible directly to cast epoxy around a RP model without damaging it. In this RP model without damaging it. In this case a case a Silicon RTV Mould Silicon RTV Mould is cast from is cast from RP pattern and silicon RTV model is RP pattern and silicon RTV model is made from the mould and is used as made from the mould and is used as pattern for aluminum fill deposited. pattern for aluminum fill deposited.

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A A loss of accuracy loss of accuracy occurs during this occurs during this succession of reproduction steps. An succession of reproduction steps. An alternative process is to build an RP mould alternative process is to build an RP mould as a master so that only a single silicon RTV as a master so that only a single silicon RTV reproduction step is needed because epoxy reproduction step is needed because epoxy tooling requires no special skill or equipment. tooling requires no special skill or equipment.

It is one of the It is one of the cheapest techniques cheapest techniques available. It is also one of the quickest. available. It is also one of the quickest. Several hundred parts can be moulded in Several hundred parts can be moulded in almost any common casting plastic material.almost any common casting plastic material.

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Epoxy Tools have the following Epoxy Tools have the following limitations.limitations. Limited tool lifeLimited tool life Poor thermal transferPoor thermal transfer Tolerance dependent on master patternsTolerance dependent on master patterns Aluminum filled epoxy has low tensile Aluminum filled epoxy has low tensile

strengthstrength

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Sand Casting Tooling:Sand Casting Tooling:

Sand casting is often used to produce Sand casting is often used to produce large metal parts with low requirement of large metal parts with low requirement of surface quality. surface quality.

Rapid prototyping techniques Rapid prototyping techniques can be can be utilized to fabricate utilized to fabricate master patternsmaster patterns using using sand moulds. sand moulds.

These moulds are produced by placing These moulds are produced by placing rapid prototyping patterns in sand box rapid prototyping patterns in sand box which is then filled and packed with sand which is then filled and packed with sand to form the mould cavity. to form the mould cavity.

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When employing rapid prototyping When employing rapid prototyping techniques it is much more convenient to techniques it is much more convenient to build patterns which include build patterns which include compensation compensation for shrinkage of the castings for shrinkage of the castings as well as as well as additional additional machining stock machining stock for areas for areas requiring machining after casting. requiring machining after casting.

The other benefits are that it significantly The other benefits are that it significantly reduces lead time reduces lead time and and increase pattern increase pattern accuracy.accuracy.

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Laminate tooling (LOM Laminate tooling (LOM Tools)Tools)

LOM process produces parts using LOM process produces parts using sheets of papersheets of paper..

Experiments to build moulds Experiments to build moulds directlydirectly or or coated with coated with thin layer of metal thin layer of metal has been has been reported.reported.

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Moulds built this way can only be used for Moulds built this way can only be used for low melting thermoplastics low melting thermoplastics and are and are not not suitable for injection mouldingsuitable for injection moulding or blow or blow moulding of common thermoplastics.moulding of common thermoplastics.

For this reason, new materials based on For this reason, new materials based on epoxy or ceramic epoxy or ceramic capable of withstanding capable of withstanding harsh operating conditions have been harsh operating conditions have been developed.developed.

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Polymer sheetsPolymer sheets: These sheets consist of : These sheets consist of glass and ceramic fibres in a B-staged epoxy glass and ceramic fibres in a B-staged epoxy matrix. Parts made with this material require matrix. Parts made with this material require post curing at 175post curing at 175ooc for one hourc for one hour. Once . Once fully cured they have fully cured they have good compressive good compressive properties and heat deflection properties and heat deflection temperature of 290temperature of 290ooc.c.

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Ceramic sheetsCeramic sheets: Two ceramic materials : Two ceramic materials have been developed for LOM, have been developed for LOM, a a sinterable AIN ceramicsinterable AIN ceramic and a and a silicon silicon infiltrable SiC ceramicinfiltrable SiC ceramic. Both materials . Both materials are mixed with are mixed with 55% by volume of 55% by volume of polymeric binderpolymeric binder..

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The ceramic process is less advanced The ceramic process is less advanced and requires more software and and requires more software and hardware modifications to the LOM hardware modifications to the LOM MachineMachine

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Direct Tooling:Direct Tooling: Indirect methods for tool production Indirect methods for tool production

necessitate a necessitate a minimum of one minimum of one intermediate replication processintermediate replication process. This . This might result in a might result in a loss of accuracyloss of accuracy and to and to increase the time for building the tool. To increase the time for building the tool. To overcome some of the drawbacks of indirect overcome some of the drawbacks of indirect method, new rapid tooling methods have method, new rapid tooling methods have come into existence that allow injection come into existence that allow injection moulding and moulding and die casting inserts to be die casting inserts to be built directly from 3D CAD modelsbuilt directly from 3D CAD models..

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Classification of Direct Classification of Direct Rapid Tooling methods:Rapid Tooling methods: Direct Rapid Tooling Processes can be divided into Direct Rapid Tooling Processes can be divided into

two main groupstwo main groups

11stst group: group: It includes It includes less expensive methods less expensive methods with with shorter shorter

lead timeslead times.. Direct RT methods that satisfy these requirements Direct RT methods that satisfy these requirements

are called methods for are called methods for firm tooling or bridge firm tooling or bridge toolingtooling..

RP processes for firm tooling fill the gap between RP processes for firm tooling fill the gap between soft and hard tooling.soft and hard tooling.

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22ndnd group: group: Solutions for Solutions for hard tooling hard tooling are based on are based on

fabrication of fabrication of sintered metal steel, iron sintered metal steel, iron copper powder inserts copper powder inserts infiltrated with copper infiltrated with copper or bronze.or bronze.

It includes RP methods that allow inserts for It includes RP methods that allow inserts for pre production and production tools to be pre production and production tools to be built.built.

These methods come under hard tooling.These methods come under hard tooling.

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Classification of Direct RT Classification of Direct RT methods:methods:

Firm Tooling MethodsFirm Tooling Methods Direct AIMDirect AIM DTM COPPER PA TOOLINGDTM COPPER PA TOOLING DTM SANDFORM TOOLINGDTM SANDFORM TOOLING ELECTRO OPTICAL SYSTEM DIRECT ELECTRO OPTICAL SYSTEM DIRECT

CHRONING PROCESSCHRONING PROCESS LOM TOOLING IN POLYMERLOM TOOLING IN POLYMER 3DP CERAMIC SHELLS3DP CERAMIC SHELLS

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Hard Tooling MethodsHard Tooling Methods EOS DIRECT TOOLEOS DIRECT TOOL DTM RAPID TOOL PROCESSDTM RAPID TOOL PROCESS LOM TOOLING IN CERAMICLOM TOOLING IN CERAMIC 3DP DIRECT METAL TOOLING3DP DIRECT METAL TOOLING

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DIRECT AIM:DIRECT AIM:DIRECT ACES INJECTION MOULDS:DIRECT ACES INJECTION MOULDS:

ACES refer to Accurate Clear Epoxy Solid.ACES refer to Accurate Clear Epoxy Solid. Stereolithography is used to produce Stereolithography is used to produce epoxy epoxy

inserts for injection mould tools inserts for injection mould tools for for thermoplastic parts because the temperature thermoplastic parts because the temperature resistance of curable epoxy resins available resistance of curable epoxy resins available at present is up to 200at present is up to 200ooc c and thermoplastics and thermoplastics are injected at temperature as high as 300are injected at temperature as high as 300oocc. . accordingly accordingly specific rules apply specific rules apply to the to the production of this type of projection tools.production of this type of projection tools.

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PROCEDURE FOR DIRECT PROCEDURE FOR DIRECT ACESACES

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Using a Using a 3D CAD package3D CAD package, the injection , the injection mould is drawn. mould is drawn.

Runners, gates, ejector pins and clearance Runners, gates, ejector pins and clearance holes are added and mould is shelled to a holes are added and mould is shelled to a recommended thickness of 1.27mm. recommended thickness of 1.27mm.

The mould is then built using accurate clear The mould is then built using accurate clear epoxy solid style on a Stereolithography epoxy solid style on a Stereolithography machine. machine.

The supports are subsequently removed The supports are subsequently removed and the mould is polished in the direction of and the mould is polished in the direction of draw to facilitate part release. draw to facilitate part release.

The thermal conductivity of SLA resin is The thermal conductivity of SLA resin is about about 300 times lower 300 times lower than that of than that of conventional tool steels (.2002 W/mK for conventional tool steels (.2002 W/mK for cibatool SL5170 epoxy resin) cibatool SL5170 epoxy resin)

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To remove the maximum amount of heat from To remove the maximum amount of heat from the tool and reduce the injection moulding cycle the tool and reduce the injection moulding cycle time, time, copper water cooling lines copper water cooling lines are added are added and the and the back of the mouldback of the mould is filled with a is filled with a mixture made up of mixture made up of 30% by volume of 30% by volume of aluminum granulate and 70% of epoxy resinaluminum granulate and 70% of epoxy resin. .

The The coolingcooling of the mould is completed by of the mould is completed by blowing air on the mould faces blowing air on the mould faces as they as they separate after the injection moulding operation.separate after the injection moulding operation.

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Disadvantages:Disadvantages:

Number of parts Number of parts that can be obtained that can be obtained using this process is very dependent on using this process is very dependent on the the shape and size shape and size of the of the moulded part moulded part as well as skills of good operator who can as well as skills of good operator who can sense when to stop between cycles to sense when to stop between cycles to allow more cooling.allow more cooling.

Process is slightly Process is slightly more difficult more difficult than than indirect methods because finishing must indirect methods because finishing must be done on internal shapes of the mould.be done on internal shapes of the mould.

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Also Also draft angles draft angles of order up to one and of order up to one and the application of the the application of the release agent release agent in in each injection cycle are required to each injection cycle are required to ensure proper part injection.ensure proper part injection.

A Direct AIM mould is A Direct AIM mould is not durable not durable like like aluminum filled epoxy mould. Injection aluminum filled epoxy mould. Injection cycle time is long.cycle time is long.

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Advantages:Advantages:

It is suitable for moulding up to It is suitable for moulding up to 100 100 partsparts..

Both resistance to Both resistance to erosionerosion and and thermal thermal conductivityconductivity of D-AIM tools can be of D-AIM tools can be increased by deposition of a 25micron increased by deposition of a 25micron layer of copper on mould surfaces.layer of copper on mould surfaces.

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Cast Kirksite ToolingCast Kirksite Tooling

Kirksite is a Kirksite is a zinc-aluminum alloy zinc-aluminum alloy with with excellent wear resistanceexcellent wear resistance. .

The process for making cast kirksite The process for making cast kirksite tooling begins much like the process for tooling begins much like the process for epoxy-based composite tooling.epoxy-based composite tooling.

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ProcedureProcedure

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First, a First, a shrink-compensatedshrink-compensated master master pattern of the part is produced, typically pattern of the part is produced, typically using an RP process.using an RP process.

A A rubber or urethane rubber or urethane material is then material is then cast against the part master to create cast against the part master to create patterns for the core and cavity set, patterns for the core and cavity set, which will be cast in kirksite.which will be cast in kirksite.

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PlasterPlaster is then cast against the core and is then cast against the core and cavity patterns to create molds into which cavity patterns to create molds into which the kirksite is cast.the kirksite is cast.

Once the kirksite is cast into the plaster Once the kirksite is cast into the plaster molds, the plaster is broken away, and molds, the plaster is broken away, and the kirksite core and cavity are fit into a the kirksite core and cavity are fit into a mold base.mold base.

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Life of cast kirksite Tooling varies from 50 Life of cast kirksite Tooling varies from 50 to 1000 pieces till 20,000 pieces.to 1000 pieces till 20,000 pieces.

Castkirksite tooling would be typically Castkirksite tooling would be typically chosen for chosen for medium-sized production medium-sized production quantities of larger parts without tight quantities of larger parts without tight dimensional requirements.dimensional requirements.

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AdvantagesAdvantages

Complex shapesComplex shapes can be molded with can be molded with kirksite tooling. kirksite tooling.

It offers a It offers a more durablemore durable mold than mold than epoxy or spray metal tooling.epoxy or spray metal tooling.

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DisadvantagesDisadvantages

Mould is not as Mould is not as accurateaccurate as an epoxy or as an epoxy or spray-metal mould because of the spray-metal mould because of the reversals and the material reversals and the material shrinkshrink in the in the metal-casting process.metal-casting process.

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