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PertanikaJ.Sci.Techno.Supplement12285992004ISSN01287680©UniversitiPutraMalaysiaPressDesignandSimulationofPlasticInjectionMouldingProcessWong,C.T.,ShamsuddinSulaiman,NapsiahIsmailA.M.S.HamoudaDepartmentofMechanicalandManufacturingEngineeringUniversitiPutraMalaysia,43400UPM,Serdang,Selangor,MalaysiaEmailschoontattm.net.my.suddineng.upm.edu.my.napsiaheng.upm.edu.my.hamoudaeng.upm.edu.myABSTRAKKertasinimembentangkanprosesrekabentuksatuacuansuntikanplastikuntukmenghasilkansatuproduk.Iadibahagikankepadatigabahagianiaitubahagianrekabentuk,bahagiansimulasidanbahagiananalisa.Plastikprodukinidirekabentukkepadaduabentukyangberlainantetapimempunyaifungsiyangsamaiaitusatuprodukmenggunakanfungsiklipdansatuproduklagimenggunakanfungsilekat.UntukRekaBentukTerbantuKomputerCAD,perisiankomputeryangdigunakanuntukmerakabentukprodukdalam3dimensi3DdanacuanialahPro/EngineerPro/E.Duaplastikprodukyangberlainanakandirekabentukdalaminsertyangbolehditukartukardidalamsatuacuanuntukmenghasilkanduaprodukyangberlainan.UntukPembuatanTerbantuKomputerCAM,Pro/ManufacturingPro/MFGdaripadaperisiankomputerProlEdigunakanuntukmenjanakanbeberapakodkawalanberangkauntukprosespemesinan.AnalisisterhadappengalirancecairplastikdijalankandenganmenggunakanperisianMoldFIowPartAdvisorversion4.Daripadaanalisisinikedudukantempatsuntikan,suhubahandantekanansuntikandapatditentukan.Jangkaankecacatanproduksepertiweldlinesdanudaraterperangkapjugaditemuidandianalisis.ABSTRACfThispaperpresentsthedesignofplasticinjectionmouldforproducingaplasticproduct.Theplasticpartwasdesignedintotwodifferenttypesofproduct,butinthesameusagefunction.Onepartisusingclipfunctionandanotherpartisusingtickfunction.InthecomputeraideddesignCAD,twoplasticpartsweredrawnin3dimension3DviewbyusingProEngineerProEparametricsoftware.InthecomputeraidedmanufacturingCAM,ProManufacturingfromProEparametricsoftwarewasusedtodevelopthemachiningprogram.Formoulddesign,theproductwasdesignedintotwochangeableinsertstoproducetwodifferenttypesofplasticproductinonemouldbase.Beforeproceedingtoinjectionmachineandmoulddesign,thispartwasanalysedandsimulatedbyusingMoldFloworPartAdvisorsoftware.Fromtheanalysisandsimulationwecandefinethemostsuitableinjectionlocation,materialtemperatureandpressureforinjection.Thepredictedweldlinesandairtrapwerealsofoundandanalysed.KeywordsChangeableinsertmould,injectionpressure,airtraps,injectionlocation,moulddesignINTRODUCTIONNowadays,thetechnologyofthetoolanddiefabricationinplasticinjectionisoneoftheworldsfastestgrowingindustries.Plasticisnowusedinalmosteveryapplication,rangingfromhouseholdarticlestospacetravel,fromtransportationtopacking,frommedicinetotoys,frombridgebuildingtosports.Generally,injectionmouldingisaprocessthatformstheplasticintoadesiredshapebymeltingtheplasticmaterialandforcingtheplasticmaterialunderpressureintothemouldcavity.Theshapeoftheplasticthatisdesiredisachievedbycoolinginthermoplasticorbychemicalreactionforthermosetting.MoulddesignandfabricationisacostlyandhightechnologyprocessbecauseitusessciencebasedcomputeraidedengineeringCAEsoftwaretoanalyseandsimulatetheWong,C.T.,ShamsuddinSulaiman,NapsiahIsmailA.M.S.Hamoudaplasticparts,computeraideddesignCADsoftwaretodesignthecomplicatedplasticproductandcomputeraidedmanufacturingCAMtodotheprogrammingfabricationtorunthecomputernumericcontrolCNCformillingorlatch.Advancesincomputertechnologyhaveledtoanincreasinglyfavorablepowertocostratioforcomputers.Sothisadvantageousandcostlytechnologywillimproveproductivityandprocessconsistency.Thus,forthisfastgrowingindustry,newtechnologiesarevitaltoensurethatthistechnologyreachesperfection.S.ocomputeraidedengineeringCAEistheassistanttoprocessandcalculatetheplasticmaterialflowinsidetheinjectionmoulding.TheoryHowPlasticFillsaMouldTheinjectionmouldingprocesscanbebrokenintothreephases1.Fillingphase2.Pressurizationphase3.CompensatingphaseFillingPhaseWhendesigningplasticpartsfortheinjectionmouldingprocess,theimportantelementtounderstandishowtheplasticisfillinginthemould.Inthemouldinjectionfillingphase,moltenplasticisinjectedintothecavityuntilthecavityisjustfilled.Asplasticflowsintothecavity,theplasticincontactwiththemouldwallquicklyfreezesandthiswillcreateafrozenlayerofplasticbetweenthemouldandthemoltenplastic.Plate1showshowtheflowfrontexpandsasmaterialfrombehindispushedforward.Theedgeoftheflowfrontcomesintocontactwiththemouldandfreezes.Themoleculesinthefrozenlayerarethereforenothighlyorientated,andoncefrozen,theorientationwillnotchange.Plate1MolJ.enplasticflowinsidethemouldTheredarrowsshowtheflowdirectionofthemoltenplastic.Thedarkbluelayersagainstthemouldwallsshowthelayersoffrozenplastic.Thegreenarrowsindicatethedirectionofheatflowfromthepolymermeltintothemouldwalls.Thefrozenlayergainsheatasmoremoltenplasticflowsthroughthecavity,andlosesheattothemould.Whenthefrozenlayerreachesacertainthickness,equilibriumisreached.Thisnormallyhappensearlyintheinjectionmouldingprocess,afterafewtenthsofasecond.PressurizationPhaseThepressurizationphasewillhappenafterthefillingphasecompletelyfillsthecavityarea.Atthisstage,alltheflowpathswillbefilledupbymoltenplastic,theedgesand86PertanikaJ.Sci.Techno.SupplementVa.12o.2,2004DesignandSimulationofPlasticInjectionMouldingProcesscornersofthefillingareainthecavitymaynotcontainplastic.Tocompletelyfilloutthegeometry,extraplasticispushedintothecavityduringthepressurizationphase.Plate2showsthedifferencebetweentheendofthefillingphaseleftimageandtheendofthepressurizationphaserightimage.oticetheunfilledcornersinsidethebluecirclesthatareleftattheendofthefillingphase.Theyellowconeindicatesthepolymerinjectionlocationandtheplasticisred.FillinRPhasePlate2DifferencebetweenjiUingandpressurizationphasePressurizationPhaseCompensatingPhasePlasticmaterialhasahighvolumetricshrinkage,formthemeltingplastictosolid,itwillshrinkageaverageof25.Thereforeafterthepressurizationphase,morematerialmustbeinjectedintothecavitytocompensatefortheplasticshrinkingafteritcools.ThisisthecompensatingphaseMoldFlowHelpFiles.MouldBasicConstructionMoulddesignandmouldmakingcanbeconsideredthemostcriticalprocessesoftheinjectionmouldingsystem.Thisisbecausethemoulddesignandmouldmakinghavetremendousimpactonproductivityandproductquality.Basically,thefunctionofthemouldistwofold.Thefirstisimpartingthedesiredshapetotheplasticizedpolymer,thesecondiscoolingtheinjectionmouldedparts.Themould,whichcontainsoneormorecavities,consistsoftwobasicpartsAstationarymouldhalfonthesidewheretheplasticisinjectedAmovinghalfontheclosingorejectorside.Theseparationofthetwomouldsiscalledthepartingline.Themouldwilldeterminethefinalproductpropertiessuchassize,shape,dimensionandfinishingsurface.Usually,themeltedplasticmaterialisfilledthroughthecentralfeedchannelcalledspruetothecavity.Themouldwillcoincidewiththeinjectionmachinecylindernozzle.Table1isthesummarylistformouldcomponentandthefunctionrespectively.MouldDesignTostartupanewmoulddesign,thedesignershouldknowsomeimportantpointstoavoidsomemistakesbeforegoingfurtherLe.productoutlookdesign,materialusage,correctshrinkageofthematerial,numberofcavitiesandselectionofthemouldbase.Makingamistakecancauseanillfittingmouldatthefinalassemblyandalsomaketheplasticproductoutoftoleranceandberejectedbythecustomer.Fig.1showsthemoulddesignerschart.PertanikaJ.Sci.Techno\.SupplementVo\.12No.2,200487/Wong,C.T.,ShamsuddinSulaiman,NapsiahIsmailA.M.S.HamoudaCreateamodelinCADsoftwareconvertinSTLJ..l.OpenthemodelinSelectaplasticmaterialPartAdvisorandsupplier.Ifasingleinjectionlocationisrequired,goontothenextstepIfmultipleinjectionlocationswanted,skipthenextstepandgototheoneafterIRunthegatelocatorIJ.IRuntheanalysisLCreateoneormoreIinjectionlocationsLookattheanalysisresult,decideifthemodelwillfilleasilyandcreategoodqualitypartsIftheresultsarenotsatisfactory,goontothenextstepIftheresultsareacceptable,skipthenextstepandgototheoneafterChangeoneoftheparametersandthenCreateareportonthereanalyze.analysisresult,usingtheTheseparametersarereportgeneratorPositionornumberofinjectionlocationJ.MaterialMouldtemperatureSendthereporttotheMelttemperaturepeoplewhoneedtoseeitInjectiontimePartgeometryFig.2ProcedurediagramforPartAdvisorsimulationMoldflowsoftware.Plate5showsthesolidmodelwithgatelocationplacingontopofthemodel.Theyellowcolourconeshapeshowstheiectionlocationinthisanalysis.Ininjectionandtransfermoulding,thegateisconsideredtheportionofthemouldedpiecethatallowsthemoltenresintoflowtherunnerorfromthesprueintothecavity.Thegatemaybethesamesizeandshapeastherunner,butgenerallyitismuchsmaller.Thereisanoptimumgatesize.Itshouldbelargeenoughforsuitablefillrateandsmallenoughtosealoffandpreventbackfloworoverpacking.ProductSimulationResultBeforestartingthesimulationprocess,someinformationhastobesetup,suchasmaterialsupplierandmaterialgrade.ThisisnormallyalreadysetintheMoldflowdatabaseandtheuserjustselectsthespecificmaterialspecification.Table2showstheelementused.forthisanalysis90PertanikaJ.Sci.Techno.SupplementVol.12No.2,2004
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