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JOURNALOFMATERIALSPROCESSINGTECHNOLOGY1712006259–267ABSTRACTTHEINUNIGRAPHICS,USINGDISTRIBRESULTSATK1INDUSTRIES,ALMOSTUSAGEBYMOLDINGTOATTHEREARETIONAPPROPRIATESYSTEMTHISWITHITYPACKE09240136/DOI101016/JJMATPROTEC200506075DESIGNANDTHERMALANALYSISOFPLASTICINJECTIONMOULDSHTANG∗,YMKONG,SMSAPUAN,RSAMIN,SSULAIMANDEPARTMENTOFMECHANICALANDMANUFACTURINGENGINEERING,UNIVERSITIPUTRAMALAYSIA,43400SERDANG,SELANGOR,MALAYSIARECEIVED3SEPTEMBER2004；ACCEPTED21JUNE2005THISPAPERPRESENTSTHEDESIGNOFAPLASTICINJECTIONMOULDFORPRODUCINGWARPAGETESTINGSPECIMENANDPERFORMINGTHERMALANALYSISFORMOULDTOACCESSONTHEEFFECTOFTHERMALRESIDUALSTRESSINTHEMOULDTHETECHNIQUE,THEORY,METHODSASWELLASCONSIDERATIONNEEDEDDESIGNINGOFPLASTICINJECTIONMOULDAREPRESENTEDDESIGNOFMOULDWASCARRIEDOUTUSINGCOMMERCIALCOMPUTERAIDEDDESIGNSOFTWAREVERSION130THEMODELFORTHERMALRESIDUALSTRESSANALYSISDUETOUNEVENCOOLINGOFTHESPECIMENWASDEVELOPEDANDSOLVEDACOMMERCIALFINITEELEMENTANALYSISSOFTWARECALLEDLUSASANALYST,VERSION135THESOFTWAREPROVIDESCONTOURPLOTOFTEMPERATUREUTIONFORTHEMODELANDALSOTEMPERATUREVARIATIONTHROUGHTHEPLASTICINJECTIONMOLDINGCYCLEBYPLOTTINGTIMERESPONSECURVESTHESHOWTHATSHRINKAGEISLIKELYTOOCCURINTHEREGIONNEARTHECOOLINGCHANNELSASCOMPAREDTOOTHERREGIONSTHISUNEVENCOOLINGEFFECTDIFFERENTREGIONSOFMOULDCONTRIBUTEDTOWARPAGE2005ELSEVIERBVALLRIGHTSRESERVEDEYWORDSPLASTICINJECTIONMOULD；DESIGN；THERMALANALYSISINTRODUCTIONBY“COOLINGSTAGE”WHERETHEMOULDISCOOLEDUNTILTHEPARTISSUFFICIENTLYRIGIDTOBEEJECTEDTHELASTSTEPISTHE“EJECTIONPLASTICINDUSTRYISONEOFTHEWORLD’SFASTESTGROWINGRANKEDASONEOFTHEFEWBILLIONDOLLARINDUSTRIESEVERYPRODUCTTHATISUSEDINDAILYLIFEINVOLVESTHEOFPLASTICANDMOSTOFTHESEPRODUCTSCANBEPRODUCEDPLASTICINJECTIONMOLDINGMETHOD1PLASTICINJECTIONPROCESSISWELLKNOWNASTHEMANUFACTURINGPROCESSCREATEPRODUCTSWITHVARIOUSSHAPESANDCOMPLEXGEOMETRYLOWCOST2THEPLASTICINJECTIONMOLDINGPROCESSISACYCLICPROCESSAREFOURSIGNIFICANTSTAGESINTHEPROCESSTHESESTAGESFILLING,PACKING,COOLINGANDEJECTIONTHEPLASTICINJECMOLDINGPROCESSBEGINSWITHFEEDINGTHERESINANDTHEADDITIVESFROMTHEHOPPERTOTHEHEATING/INJECTIONOFTHEINJECTIONPLASTICINJECTIONMOLDINGMACHINE3ISTHE“FILLINGSTAGE”INWHICHTHEMOULDCAVITYISFILLEDHOTPOLYMERMELTATINJECTIONTEMPERATUREAFTERTHECAVISFILLED,INTHE“PACKINGSTAGE”,ADDITIONALPOLYMERMELTISEDINTOTHECAVITYATAHIGHERPRESSURETOCOMPENSATETHEXPECTEDSHRINKAGEASTHEPOLYMERSOLIDIFIESTHISISFOLLOWED∗CORRESPONDINGAUTHOREMAILADDRESSSAIHONGENGUPMEDUMYSHTANGSTAGE”AFTER4MERICNATEDACTUALTHECOREANDFMOULDGATINGTOSTRESSESDEMOLDEDCONDUCTIMOLTENE–SEEFRONTMATTER2005ELSEVIERBVALLRIGHTSRESERVEDINWHICHTHEMOULDISOPENEDANDTHEPARTISEJECTED,WHICHTHEMOULDISCLOSEDAGAINTOBEGINTHENEXTCYCLETHEDESIGNANDMANUFACTUREOFINJECTIONMOLDEDPOLYPARTSWITHDESIREDPROPERTIESISACOSTLYPROCESSDOMIBYEMPIRICISM,INCLUDINGTHEREPEATEDMODIFICATIONOFTOOLINGAMONGTHETASKOFMOULDDESIGN,DESIGNINGMOULDSPECIFICSUPPLEMENTARYGEOMETRY,USUALLYONTHESIDE,ISQUITECOMPLICATEDBYTHEINCLUSIONOFPROJECTIONDEPRESSION5INORDERTODESIGNAMOULD,MANYIMPORTANTDESIGNINGACTORSMUSTBETAKENINTOCONSIDERATIONTHESEFACTORSARESIZE,NUMBEROFCAVITY,CAVITYLAYOUTS,RUNNERSYSTEMS,SYSTEMS,SHRINKAGEANDEJECTIONSYSTEM6INTHERMALANALYSISOFTHEMOULD,THEMAINOBJECTIVEISANALYZETHEEFFECTOFTHERMALRESIDUALSTRESSORMOLDEDINONPRODUCTDIMENSIONTHERMALLYINDUCEDSTRESSESVELOPPRINCIPALLYDURINGTHECOOLINGSTAGEOFANINJECTIONPART,MAINLYASACONSEQUENCEOFITSLOWTHERMALVITYANDTHEDIFFERENCEINTEMPERATUREBETWEENTHERESINANDTHEMOULDANUNEVENTEMPERATUREFIELDXISTSAROUNDPRODUCTCAVITYDURINGCOOLING7260PROCESSINGENCESCHANNELESIGNIFICANTFORE,OFUNDERSTANDINGTION,BEPRODUCINGMALRESIDUAL221SPECIMENTHATTHINUCTTHEMOULDEDSHELL120MATERIALWTEMPERATURE,RESPECTIDUCED22TESTINGERATIONSTESTINGINJECTIONCARBONTHEIIIIIMEN,DESIGNSIONISMACHINETHETHEREFORE,NOTRESERVSETTINGUPSHTANGETAL/JOURNALOFMATERIALSDURINGCOOLING,LOCATIONNEARTHECOOLINGCHANNELEXPERIMORECOOLINGTHANLOCATIONFARAWAYFROMTHECOOLINGTHISDIFFERENTTEMPERATURECAUSESTHEMATERIALTOXPERIENCEDIFFERENTIALSHRINKAGECAUSINGTHERMALSTRESSESTHERMALSTRESSCANCAUSEWARPAGEPROBLEMTHEREITISIMPORTANTTOSIMULATETHETHERMALRESIDUALSTRESSFIELDTHEINJECTIONMOLDEDPARTDURINGTHECOOLINGSTAGE8BYTHECHARACTERISTICSOFTHERMALSTRESSDISTRIBUDEFORMATIONCAUSEDBYTHETHERMALRESIDUALSTRESSCANPREDICTEDINTHISPAPERTHEDESIGNOFAPLASTICINJECTIONMOULDFORWARPAGETESTINGSPECIMENANDFORPERFORMINGTHERANALYSISFORTHEMOULDTOACCESSONTHEEFFECTOFTHERMALSTRESSINTHEMOULDISPRESENTEDMETHODOLOGYDESIGNOFWARPAGETESTINGSPECIMENTHISSECTIONILLUSTRATESTHEDESIGNOFTHEWARPAGETESTINGTOBEUSEDINPLASTICINJECTIONMOULDITISCLEARWARPAGEISTHEMAINPROBLEMTHATEXISTSINPRODUCTWITHSHELLFEATURETHEREFORE,THEMAINPURPOSEOFTHEPRODDEVELOPMENTISTODESIGNAPLASTICPARTFORDETERMININGEFFECTIVEFACTORSINTHEWARPAGEPROBLEMOFANINJECTIONPARTWITHATHINSHELLTHEWARPAGETESTINGSPECIMENISDEVELOPEDFROMTHINPLASTICSTHEOVERALLDIMENSIONSOFTHESPECIMENWEREMMINLENGTH,50MMINWIDTHAND1MMINTHICKNESSTHEUSEDFORPRODUCINGTHEWARPAGETESTINGSPECIMENASACRYLONITRILEBUTADIENESTYLENEABSANDTHEINJECTIONTIMEANDPRESSUREWERE210◦C,3SAND60MPA,VELYFIG1SHOWSTHEWARPAGETESTINGSPECIMENPRODESIGNOFPLASTICINJECTIONMOULDFORWARPAGESPECIMENTHISSECTIONDESCRIBESTHEDESIGNASPECTSANDOTHERCONSIDINVOLVEDINDESIGNINGTHEMOULDTOPRODUCEWARPAGESPECIMENTHEMATERIALUSEDFORPRODUCINGTHEPLASTICFIG1WARPAGETESTINGSPECIMENPRODUCEDIMUMBASEFITTEDLOSIONSHAREACTIONTHERESPECTIONSPACEWITHTHEREFORE,TMOULDCOMPONENTSTCACORESIDEEJECTOREJECTORBOTTOMTECHNOLOGY1712006259–267MOULDFORWARPAGETESTINGSPECIMENWASAISI1050STEELFOURDESIGNCONCEPTSHADBEENCONSIDEREDINDESIGNINGOFMOULDINCLUDINGITHREEPLATEMOULDCONCEPT1HAVINGTWOPARTINGLINEWITHSINGLECAVITYNOTAPPLICABLEDUETOHIGHCOSTIITWOPLATEMOULDCONCEPT2HAVINGONEPARTINGLINEWITHSINGLECAVITYWITHOUTGATINGSYSTEMNOTAPPLICABLEDUETOLOWPRODUCTIONQUANTITYPERINJECTIONTWOPLATEMOULDCONCEPT3HAVINGONEPARTINGLINEWITHDOUBLECAVITIESWITHGATINGANDEJECTIONSYSTEMNOTAPPLICABLEASEJECTORPINSMIGHTDAMAGETHEPRODUCTASTHEPRODUCTISTOOTHINVTWOPLATEMOULDCONCEPT4HAVINGONEPARTINGLINEWITHDOUBLECAVITIESWITHGATINGSYSTEM,ONLYUSEDSPRUEPULLERACTASEJECTORTOAVOIDPRODUCTDAMAGEDURINGEJECTIONINDESIGNINGOFTHEMOULDFORTHEWARPAGETESTINGSPECTHEFOURTHDESIGNCONCEPTHADBEENAPPLIEDVARIOUSCONSIDERATIONSHADBEENAPPLIEDINTHEDESIGNFIRSTLY,THEMOULDWASDESIGNEDBASEDONTHEPLATENDIMENOFTHEPLASTICINJECTIONMACHINEUSEDBOY22DTHEREALIMITATIONOFTHEMACHINE,WHICHISTHEMAXIMUMAREAOFPLATENISGIVENBYTHEDISTANCEBETWEENTWOTIEBARSDISTANCEBETWEENTIEBARSOFTHEMACHINEIS254MMTHEMAXIMUMWIDTHOFTHEMOULDPLATESHOULDEXCEEDTHISDISTANCEFURTHERMORE,4MMSPACEHADBEENEDBETWEENTHETWOTIEBARSANDTHEMOULDFORMOULDANDHANDLINGPURPOSESTHISGIVESTHEFINALMAXWIDTHOFTHEMOULDAS250MMTHESTANDARDMOULDWITH250MM250MMISEMPLOYEDTHEMOULDBASEISTOTHEMACHINEUSINGMATEXCLAMPATTHEUPPERRIGHTANDWERLEFTCORNEROFTHEMOULDBASEORMOULDPLATENDIMENOFOTHERRELATEDMOULDPLATESARESHOWNINTABLE1THEMOULDHADBEENDESIGNEDWITHCLAMPINGPRESSUREVINGCLAMPINGFORCEHIGHERTHANTHEINTERNALCAVITYFORCEFORCETOAVOIDFLASHINGFROMHAPPENINGBASEDONTHEDIMENSIONSPROVIDEDBYSTANDARDMOULDSET,WIDTHANDTHEHEIGHTOFTHECOREPLATEARE200AND250MM,VELYTHESEDIMENSIONSENABLEDDESIGNOFTWOCAVITIESCOREPLATETOBEPLACEDHORIZONTALLYASTHEREISENOUGHWHILETHECAVITYPLATEISLEFTEMPTYANDITISONLYFIXEDSPRUEBUSHINGFORTHEPURPOSEOFFEEDINGMOLTENPLASTICSITISONLYONESTANDARDPARTINGLINEWASDESIGNEDATABLE1PLATESDIMENSIONSSIZEMM−WIDTHHEIGHTTHICKNESSOPCLAMPINGPLATE25025025VITYPLATE20025040PLATE20025040PLATE/SUPPORTPLATE3725070RETAINERPLATE12025015PLATE12025020CLAMPINGPLATE25025025PROCESSINGTHERELEASEDOPENINGISLANDONLYWFORRUNNERINGCASEMORETYPETHISTHEDIAMETERORSAMETHEAIRANDFLASHINGINORTHATOCCURRINGCAECACIENTSHOCORETHEFIG2CAVITYLAYOUTWITHAIRVENTSANDCOOLINGCHANNELSPLATETHESPRUEPULLERLOCATEDATTHECENTEROFCOREPLATENOTONLYFUNCTIONSASTHEPULLERTOHOLDTHEPRODUCTINPOSITIONWHENTHEMOULDISOPENEDBUTITALSOACTSASEJECTORTOPUSHTHEPRODUCTOUTOFTHEMOULDDURINGEJECTIONSTAGENOADDITIONALEJECTORISUSEDORLOCATEDATPRODUCTCAVITIESBECAUSETHEPRODUCTPRODUCEDISVERYTHIN,IE1MMADDITIONALEJECTORINTHEPRODUCTCAVITYAREAMIGHTCREATEHOLEANDDAMAGETOTHEPRODUCTDURINGEJECTIONFINALLY,ENOUGHTOLERANCEOFDIMENSIONSISGIVENCONSIDERATIONTOCOMPENSATEFORSHRINKAGEOFMATERIALSFIG3SHOWS3DSOLIDMODELINGASWELLASTHEWIREFRAMEMODELINGOFTHEMOULDDEVELOPEDUSINGUNIGRAPHICSSHTANGETAL/JOURNALOFMATERIALSSURFACEOFTHEPRODUCTTHEPRODUCTANDTHERUNNERWEREINAPLANETHROUGHTHEPARTINGLINEDURINGMOULDSTANDARDORSIDEGATEWASDESIGNEDFORTHISMOULDTHEGATELOCATEDBETWEENTHERUNNERANDTHEPRODUCTTHEBOTTOMOFTHEGATEWASDESIGNEDTOHAVE20◦SLANTINGANDHAS05MMTHICKNESSFOREASYDEGATINGPURPOSETHEGATEASALSODESIGNEDTOHAVE4MMWIDTHAND05MMTHICKNESSTHEENTRANCEOFMOLTENPLASTICINTHEMOULDDESIGN,THEPARABOLICCROSSSECTIONTYPEOFWASSELECTEDASITHASTHEADVANTAGEOFSIMPLERMACHININONEMOULDHALFONLY,WHICHISTHECOREPLATEINTHISHOWEVER,THISTYPEOFRUNNERHASDISADVANTAGESSUCHASHEATLOSSANDSCRAPCOMPAREDWITHCIRCULARCROSSSECTIONTHISMIGHTCAUSETHEMOLTENPLASTICTOSOLIDIFYFASTERPROBLEMWASREDUCEDBYDESIGNINGINSUCHAWAYTHATRUNNERISSHORTANDHASLARGERDIAMETER,WHICHIS6MMINITISIMPORTANTTHATTHERUNNERDESIGNEDDISTRIBUTESMATERIALMOLTENPLASTICINTOCAVITIESATTHESAMETIMEUNDERTHEPRESSUREANDWITHTHESAMETEMPERATUREDUETOTHIS,CAVITYLAYOUTHADBEENDESIGNEDINSYMMETRICALFORMANOTHERDESIGNASPECTTHATISTAKENINTOCONSIDERATIONWASVENTDESIGNTHEMATINGSURFACEBETWEENTHECOREPLATETHECAVITYPLATEHASVERYFINEFINISHINGINORDERTOPREVENTFROMTAKINGPLACEHOWEVER,THISCANCAUSEAIRTOTRAPTHECAVITYWHENTHEMOULDISCLOSEDANDCAUSESHORTSHOTINCOMPLETEPARTSUFFICIENTAIRVENTWASDESIGNEDTOENSUREAIRTRAPCANBERELEASEDTOAVOIDINCOMPLETEPARTFROMTHECOOLINGSYSTEMWASDRILLEDALONGTHELENGTHOFTHEVITIESANDWASLOCATEDHORIZONTALLYTOTHEMOULDTOALLOWVENCOOLINGTHESECOOLINGCHANNELSWEREDRILLEDONBOTHVITYANDCOREPLATESTHECOOLINGCHANNELSPROVIDEDSUFFICOOLINGOFTHEMOULDINTHECASEOFTURBULENTFLOWFIG2WSCAVITYLAYOUTWITHAIRVENTSANDCOOLINGCHANNELSONPLATEINTHISMOULDDESIGN,THEEJECTIONSYSTEMONLYCONSISTSOFEJECTORRETAINERPLATE,SPRUEPULLERANDALSOTHEEJECTOR331TESTINGRUNSHORTAIRFIG33DSOLIDMODELINGANDWIREFRAMETECHNOLOGY1712006259–267261RESULTSANDDISCUSSIONRESULTSOFPRODUCTPRODUCTIONANDMODIFICATIONFROMTHEMOULDDESIGNEDANDFABRICATED,THEWARPAGESPECIMENSPRODUCEDHAVESOMEDEFECTSDURINGTRIALTHEDEFECTSARESHORTSHOT,FLASHINGANDWARPAGETHESHOTISSUBSEQUENTLYELIMINATEDBYMILLINGOFADDITIONALVENTSATCORNERSOFTHECAVITIESTOALLOWAIRTRAPPEDTOMODELINGOFTHEMOULD262PROCESSINGESCAPEPACKINGBYINJECTIONIT
