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JournalofMaterialsProcessingTechnology1712006259–267AbstracttheinUnigraphics,usingdistribresultsat©K1.industries,AlmostusagebymoldingtoatTherearetionappropriatesystemThiswithitypacke09240136/doi10.1016/j.jmatprotec.2005.06.075DesignandthermalanalysisofplasticinjectionmouldS.H.Tang∗,Y.M.Kong,S.M.Sapuan,R.Samin,S.SulaimanDepartmentofMechanicalandManufacturingEngineering,UniversitiPutraMalaysia,43400Serdang,Selangor,MalaysiaReceived3September2004accepted21June2005Thispaperpresentsthedesignofaplasticinjectionmouldforproducingwarpagetestingspecimenandperformingthermalanalysisformouldtoaccessontheeffectofthermalresidualstressinthemould.Thetechnique,theory,methodsaswellasconsiderationneededdesigningofplasticinjectionmouldarepresented.DesignofmouldwascarriedoutusingcommercialcomputeraideddesignsoftwareVersion13.0.ThemodelforthermalresidualstressanalysisduetounevencoolingofthespecimenwasdevelopedandsolvedacommercialfiniteelementanalysissoftwarecalledLUSASAnalyst,Version13.5.Thesoftwareprovidescontourplotoftemperatureutionforthemodelandalsotemperaturevariationthroughtheplasticinjectionmoldingcyclebyplottingtimeresponsecurves.Theshowthatshrinkageislikelytooccurintheregionnearthecoolingchannelsascomparedtootherregions.Thisunevencoolingeffectdifferentregionsofmouldcontributedtowarpage.2005ElsevierB.V.Allrightsreserved.eywordsPlasticInjectionmouldDesignThermalanalysisIntroductionbycoolingstagewherethemouldiscooleduntilthepartissufficientlyrigidtobeejected.ThelaststepistheejectionPlasticindustryisoneoftheworldsfastestgrowingrankedasoneofthefewbilliondollarindustries.everyproductthatisusedindailylifeinvolvestheofplasticandmostoftheseproductscanbeproducedplasticinjectionmoldingmethod1.Plasticinjectionprocessiswellknownasthemanufacturingprocesscreateproductswithvariousshapesandcomplexgeometrylowcost2.Theplasticinjectionmoldingprocessisacyclicprocess.arefoursignificantstagesintheprocess.Thesestagesfilling,packing,coolingandejection.Theplasticinjecmoldingprocessbeginswithfeedingtheresinandtheadditivesfromthehoppertotheheating/injectionoftheinjectionplasticinjectionmoldingmachine3.isthefillingstageinwhichthemouldcavityisfilledhotpolymermeltatinjectiontemperature.Afterthecavisfilled,inthepackingstage,additionalpolymermeltisedintothecavityatahigherpressuretocompensatethexpectedshrinkageasthepolymersolidifies.Thisisfollowed∗Correspondingauthor.Emailaddresssaihongeng.upm.edu.myS.H.Tang.stageafter4mericnatedactualthecoreandfmouldgatingtostressesdemoldedconductimoltene–seefrontmatter©2005ElsevierB.V.Allrightsreserved.inwhichthemouldisopenedandthepartisejected,whichthemouldisclosedagaintobeginthenextcycle.Thedesignandmanufactureofinjectionmoldedpolypartswithdesiredpropertiesisacostlyprocessdomibyempiricism,includingtherepeatedmodificationoftooling.Amongthetaskofmoulddesign,designingmouldspecificsupplementarygeometry,usuallyontheside,isquitecomplicatedbytheinclusionofprojectiondepression5.Inordertodesignamould,manyimportantdesigningactorsmustbetakenintoconsideration.Thesefactorsaresize,numberofcavity,cavitylayouts,runnersystems,systems,shrinkageandejectionsystem6.Inthermalanalysisofthemould,themainobjectiveisanalyzetheeffectofthermalresidualstressormoldedinonproductdimension.Thermallyinducedstressesvelopprincipallyduringthecoolingstageofaninjectionpart,mainlyasaconsequenceofitslowthermalvityandthedifferenceintemperaturebetweentheresinandthemould.Anuneventemperaturefieldxistsaroundproductcavityduringcooling7.260Processingenceschannel.eSignificantfore,ofunderstandingtion,beproducingmalresidual2.2.1.specimenthatthinuctthemouldedshell120materialwtemperature,respectiduced.2.2.testingerationstestinginjectioncarbontheiii.iimen,designsionismachineTheTherefore,notreservsettingupS.H.Tangetal./JournalofMaterialsDuringcooling,locationnearthecoolingchannelexperimorecoolingthanlocationfarawayfromthecoolingThisdifferenttemperaturecausesthematerialtoxperiencedifferentialshrinkagecausingthermalstresses.thermalstresscancausewarpageproblem.Thereitisimportanttosimulatethethermalresidualstressfieldtheinjectionmoldedpartduringthecoolingstage8.Bythecharacteristicsofthermalstressdistribudeformationcausedbythethermalresidualstresscanpredicted.Inthispaperthedesignofaplasticinjectionmouldforwarpagetestingspecimenandforperformingtheranalysisforthemouldtoaccessontheeffectofthermalstressinthemouldispresented.MethodologyDesignofwarpagetestingspecimenThissectionillustratesthedesignofthewarpagetestingtobeusedinplasticinjectionmould.Itisclearwarpageisthemainproblemthatexistsinproductwithshellfeature.Therefore,themainpurposeoftheproddevelopmentistodesignaplasticpartfordeterminingeffectivefactorsinthewarpageproblemofaninjectionpartwithathinshell.Thewarpagetestingspecimenisdevelopedfromthinplastics.Theoveralldimensionsofthespecimenweremminlength,50mminwidthand1mminthickness.TheusedforproducingthewarpagetestingspecimenasacrylonitrilebutadienestyleneABSandtheinjectiontimeandpressurewere210◦C,3sand60MPa,vely.Fig.1showsthewarpagetestingspecimenproDesignofplasticinjectionmouldforwarpagespecimenThissectiondescribesthedesignaspectsandotherconsidinvolvedindesigningthemouldtoproducewarpagespecimen.ThematerialusedforproducingtheplasticFig.1.Warpagetestingspecimenproduced.imumbasefittedlosionshareactiontherespectionspacewithTherefore,TMouldComponentsTCaCoreSideEjectorEjectorBottomTechnology1712006259–267mouldforwarpagetestingspecimenwasAISI1050steel.Fourdesignconceptshadbeenconsideredindesigningofmouldincludingi.ThreeplatemouldConcept1havingtwopartinglinewithsinglecavity.Notapplicableduetohighcost.ii.TwoplatemouldConcept2havingonepartinglinewithsinglecavitywithoutgatingsystem.Notapplicableduetolowproductionquantityperinjection.TwoplatemouldConcept3havingonepartinglinewithdoublecavitieswithgatingandejectionsystem.Notapplicableasejectorpinsmightdamagetheproductastheproductistoothin.v.TwoplatemouldConcept4havingonepartinglinewithdoublecavitieswithgatingsystem,onlyusedspruepulleractasejectortoavoidproductdamageduringejection.Indesigningofthemouldforthewarpagetestingspecthefourthdesignconcepthadbeenapplied.Variousconsiderationshadbeenappliedinthedesign.Firstly,themouldwasdesignedbasedontheplatendimenoftheplasticinjectionmachineusedBOY22D.Therealimitationofthemachine,whichisthemaximumareaofplatenisgivenbythedistancebetweentwotiebars.distancebetweentiebarsofthemachineis254mm.themaximumwidthofthemouldplateshouldexceedthisdistance.Furthermore,4mmspacehadbeenedbetweenthetwotiebarsandthemouldformouldandhandlingpurposes.Thisgivesthefinalmaxwidthofthemouldas250mm.Thestandardmouldwith250mm250mmisemployed.ThemouldbaseistothemachineusingMatexclampattheupperrightandwerleftcornerofthemouldbaseormouldplaten.DimenofotherrelatedmouldplatesareshowninTable1.Themouldhadbeendesignedwithclampingpressurevingclampingforcehigherthantheinternalcavityforceforcetoavoidflashingfromhappening.Basedonthedimensionsprovidedbystandardmouldset,widthandtheheightofthecoreplateare200and250mm,vely.Thesedimensionsenableddesignoftwocavitiescoreplatetobeplacedhorizontallyasthereisenoughwhilethecavityplateisleftemptyanditisonlyfixedspruebushingforthepurposeoffeedingmoltenplastics.itisonlyonestandardpartinglinewasdesignedatable1platesdimensions.Sizemm−widthheightthicknessopclampingplate25025025vityplate20025040plate20025040plate/supportplate3725070retainerplate12025015plate12025020clampingplate25025025Processingthereleasedopening.islandonlywforrunneringcase.moretype.Thisthediameterorsametheairandflashinginorthatoccurring.caecacientshocoretheFig.2.Cavitylayoutwithairventsandcoolingchannels.plate.Thespruepullerlocatedatthecenterofcoreplatenotonlyfunctionsasthepullertoholdtheproductinpositionwhenthemouldisopenedbutitalsoactsasejectortopushtheproductoutofthemouldduringejectionstage.Noadditionalejectorisusedorlocatedatproductcavitiesbecausetheproductproducedisverythin,i.e.1mm.Additionalejectorintheproductcavityareamightcreateholeanddamagetotheproductduringejection.Finally,enoughtoleranceofdimensionsisgivenconsiderationtocompensateforshrinkageofmaterials.Fig.3shows3DsolidmodelingaswellasthewireframemodelingofthemoulddevelopedusingUnigraphics.S.H.Tangetal./JournalofMaterialssurfaceoftheproduct.TheproductandtherunnerwereinaplanethroughthepartinglineduringmouldStandardorsidegatewasdesignedforthismould.Thegatelocatedbetweentherunnerandtheproduct.Thebottomofthegatewasdesignedtohave20◦slantingandhas0.5mmthicknessforeasydegatingpurpose.Thegateasalsodesignedtohave4mmwidthand0.5mmthicknesstheentranceofmoltenplastic.Inthemoulddesign,theparaboliccrosssectiontypeofwasselectedasithastheadvantageofsimplermachininonemouldhalfonly,whichisthecoreplateinthisHowever,thistypeofrunnerhasdisadvantagessuchasheatlossandscrapcomparedwithcircularcrosssectionThismightcausethemoltenplastictosolidifyfaster.problemwasreducedbydesigninginsuchawaythatrunnerisshortandhaslargerdiameter,whichis6mmin.Itisimportantthattherunnerdesigneddistributesmaterialmoltenplasticintocavitiesatthesametimeunderthepressureandwiththesametemperature.Duetothis,cavitylayouthadbeendesignedinsymmetricalform.Anotherdesignaspectthatistakenintoconsiderationwasventdesign.Thematingsurfacebetweenthecoreplatethecavityplatehasveryfinefinishinginordertopreventfromtakingplace.However,thiscancauseairtotrapthecavitywhenthemouldisclosedandcauseshortshotincompletepart.SufficientairventwasdesignedtoensureairtrapcanbereleasedtoavoidincompletepartfromThecoolingsystemwasdrilledalongthelengthofthevitiesandwaslocatedhorizontallytothemouldtoallowvencooling.Thesecoolingchannelsweredrilledonbothvityandcoreplates.Thecoolingchannelsprovidedsufficoolingofthemouldinthecaseofturbulentflow.Fig.2wscavitylayoutwithairventsandcoolingchannelsonplate.Inthismoulddesign,theejectionsystemonlyconsistsofejectorretainerplate,spruepullerandalsotheejector3.3.1.testingrun.shortairFig.3.3DsolidmodelingandwireframeTechnology1712006259–267261ResultsanddiscussionResultsofproductproductionandmodificationFromthemoulddesignedandfabricated,thewarpagespecimensproducedhavesomedefectsduringtrialThedefectsareshortshot,flashingandwarpage.Theshotissubsequentlyeliminatedbymillingofadditionalventsatcornersofthecavitiestoallowairtrappedtomodelingofthemould.262Processingescape.packingbyinjectionitylittletheeliminate3.2.oftionthedirectedthe35mensureselectedingfiniteandcoreformed.Fig.5.Modelforthermalanalysis.TMaterialCarbonDensityYPoissonYTThermalConductiSpecificS.H.Tangetal./JournalofMaterialsFig.4.Extraairventstoavoidshortshot.Meanwhile,flashingwasreducedbyreducingthepressureofthemachine.Warpagecanbecontrolledcontrollingvariousparameterssuchastheinjectiontime,temperatureandmeltingtemperature.Afterthesemodifications,themouldproducedhighqualwarpagetestingspecimenwithlowcostandrequiredfinishingbydegating.Fig.4showsmodificationsofmould,whichismachiningofextraairventsthatcanshortshot.DetailanalysisofmouldandproductAfterthemouldandproductsweredeveloped,theanalysismouldandtheproductwascarriedout.Intheplasticinjecmouldingprocess,moltenABSat210◦Cisinjectedintomouldthroughthespruebushingonthecavityplateandintotheproductcavity.Aftercoolingtakesplace,productisformed.Onecycleoftheproducttakesaboutsincluding20sofcoolingtime.ThematerialusedforproducingwarpagetestingspeciwasABSandtheinjectiontemperature,timeandpreswere210◦C,3sand60MParespectively.ThematerialforthemouldwasAISI1050carbonsteel.Propertiesofthesematerialswereimportantindetermintemperaturedistributioninthemouldcarriedoutusingelementanalysis.Table2showsthepropertiesforABSAISI1050carbonsteel.ThecriticalpartofanalysisformouldisonthecavityandplatebecausethesearetheplacewheretheproductisTherefore,thermalanalysistostudythetemperaturedistribperformedcalled2DofmodelingsidetogetheranalysisandelementresponsedurationanalysisBasicallythethethe3.3.analysistimeable2propertiesformouldandproductSteelAISI1050,mould,ρ7860kg/m3oungsmodulus,E208GPasratio,ν0.297ieldstrength,SY365.4MPaensilestrength,SUTS636MPaexpansion,α11.6510−6K−1vity,k49.4W/mKheat,c477J/kgKTechnology1712006259–267utionandtemperatureatthroughdifferenttimesareusingcommercialfiniteelementanalysissoftwareLUSASAnalyst,Version13.5.Atwodimensionalthermalanalysisiscarriedoutfortostudytheeffectthermalresidualstressonthemouldatdifferentregions.Duetosymmetry,thethermalanalysiswasperformedbyonlythetophalfoftheverticalcrosssectionorviewofboththecavityandcoreplatethatwereclampedduringinjection.Fig.5showsthemodelofthermalanalyzedwithirregularmeshing.Modelingforthemodelalsoinvolvesassigningpropertiesprocessorcycletimetothemodel.Thisallowedthefinitesolvertoanalyzethemouldmodeledandplottimegraphstoshowtemperaturevariationoveracertainandatdifferentregions.Fortheproductanalysis,atwodimensionaltensilestresswascarriedusingLUSASAnalyst,Version13.5.theproductwasloadedintensionononeendwhileotherendisclamped.Loadincrementswereapplieduntilmodelreachesplasticity.Fig.6showsloadedmodelofanalysis.ResultanddiscussionformouldandproductFormouldanalysis,thethermaldistributionatdifferentintervalswasobserved.Fig.7showsthe2DanalysisABSPolymer,productDensity,ρ1050kg/m3Youngsmodulus,E2.519GPaPoissonsratio,ν0.4Yieldstrength,SY65MPaThermalexpansion,α6510−6K−1Conductivity,k0.135W/mKSpecificheat,c1250J/kgK