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JournalofMaterialsProcessingTechnology187–188(2007)690–693AdaptivesystemforelectricallydriventhermoregulationofmouldsforinjectionmouldingB.Nardina,∗,B.ˇZagara,∗,A.Glojeka,D.KriˇzajbaTECOS,ToolandDieDevelopmentCentreofSlovenia,KidriˇcevaCesta25,3000Celje,SloveniabFacultyofElectricalEngineering,Ljubljana,SloveniaAbstractOneofthebasicproblemsinthedevelopmentandproductionprocessofmouldsforinjectionmouldingisthecontroloftemperaturecon-ditionsinthemould.Precisestudyofthermodynamicprocessesinmouldsshowed,thatheatexchangecanbemanipulatedbythermoelectricalmeans.Suchsystemupgradesconventionalcoolingsystemswithinthemouldorcanbeastandaloneapplicationforheatmanipulationwithinit.Inthepaper,theauthorswillpresentresultsoftheresearchproject,whichwascarriedoutinthreephasesanditsresultsarepatentedinA686\2006patent.Thetestingstage,theprototypestageandtheindustrializationphasewillbepresented.Themainresultsoftheprojectweretotalandrapidon-linethermoregulationofthemouldoverthecycletimeandoverallinfluenceonqualityofplasticproductwithemphasisondeformationcontrol.Presentedapplicationcanpresentamilestoneinthefieldofmouldtemperatureandproductqualitycontrolduringtheinjectionmouldingprocess.©2006ElsevierB.V.Allrightsreserved.Keywords:Injectionmoulding;Mouldcooling;Thermoelectricmodules;FEMsimulations1.Introduction,definitionofproblemDevelopmentoftechnologyofcoolingmouldsviathermo-electrical(TEM)meansderivesoutoftheindustrialpraxisandproblems,i.e.atdesign,toolmakingandexploitationoftools.Currentcoolingtechnologieshavetechnologicallimitations.Theirlimitationscanbelocatedandpredictedinadvancewithfiniteelementanalyses(FEA)simulationpackagesbutnotcom-pletelyavoided.Resultsofadiversestateoftheartanalysesrevealedthatallexistingcoolingsystemsdonotprovidecon-trollableheattransfercapabilitiesadequatetofitintodemand-ingtechnologicalwindowsofcurrentpolymerprocessingtechnologies.Polymerprocessingisnowadayslimited(intermofshort-eningtheproductioncycletimeandwithinthatreducingcosts)onlywithheatcapacitymanipulationcapabilities.Otherproduc-tionoptimizationcapabilitiesarealreadydriventomechanicalandpolymerprocessinglimitations[3].∗Correspondingauthors.Tel.:[phone];fax:[phone].E-mailaddress:[e-mail](B.Nardin).1.1.ThermalprocessesininjectionmouldingplasticprocessingPlasticprocessingisbasedonheattransferbetweenplasticmaterialandmouldcavity.Withincalculationofheattransferoneshouldconsidertwomajorfacts:firstisallusedenergywhichisbasedonfirstlawofthermodynamics—lawofenergyconservation[1],secondisvelocityofheattransfer.Basictaskatheattransferanalysesistemperaturecalculationovertimeanditsdistributioninsidestudiedsystem.Thatlastdependsonvelocityofheattransferbetweenthesystemandsurroundingsandvelocityofheattransferinsidethesystem.Heattransfercanbebasedasheatconduction,convectionandradiation[1].1.2.CoolingtimeCompleteinjectionmouldingprocesscyclecomprisesofmouldclosingphase,injectionofmeltintocavity,packingpres-surephaseforcompensatingshrinkageeffect,coolingphase,mouldopeningphaseandpartejectionphase.Inmostcases,thelongesttimeofallphasesdescribedaboveiscoolingtime.Coolingtimeininjectionmouldingprocessisdefinedastimeneededtocooldowntheplasticpartdowntoejectiontemperature[1].0924-0136/$–seefrontmatter©2006ElsevierB.V.Allrightsreserved.doi:10.1016/j.jmatprotec.2006.11.052B.Nardinetal./JournalofMaterialsProcessingTechnology187–188(2007)690–693691Fig.1.Mouldtemperaturevariationacrossonecycle[2].Themainaimofacoolingprocessistoloweradditionalcoolingtimewhichistheoreticallyneedless;inpraxis,itextendsfrom45upto67%ofthewholecycletime[1,4].Fromliteratureandexperiments[1,4],itcanbeseen,thatthemouldtemperaturehasenormousinfluenceontheejectiontimeandthereforethecoolingtime(costs).InjectionmouldingprocessisacyclicprocesswheremouldtemperaturevariesasshowninFig.1wheretemperaturevariesfromaveragevaluethroughwholecycletime.2.CoolingtechnologyforplasticinjectionmouldsAsitwasalreadydescribed,therearealreadyseveraldiffer-enttechnologies,enablingtheuserstocoolthemoulds[5].Themostconventionalisthemethodwiththedrillingtechnology,i.e.producingholesinthemould.Throughtheseholes(coolinglines),thecoolingmediaisflowing,removingthegeneratedandaccumulatedheatfromthemould[1,2].Itisalsoveryconvenienttobuildindifferentmaterials,withdifferentthermalconductiv-itywiththeaimtoenhancecontrolovertemperatureconditionsinthemould.Suchapproachesaresocalledpassiveapproachestowardsthemouldtemperaturecontrol.Thechallengingtaskistomakeanactivesystem,whichcanalterthethermalconditions,regardingtothedesiredaspects,likeproductqualityorcyclestime.Oneofsuchapproachesisintegratingthermalelectricalmodules(TEM),whichcanalterthethermalconditionsinthemould,regardingthedesiredprop-erties.Withsuchapproach,theonecancontroltheheattransferwiththetimeandspacevariable,whatmeans,thatthetemper-aturecanberegulatedthroughouttheinjectionmouldingcycle,independentofthepositioninthemould.Theheatcontrolisdonebythecontrolunit,wheretheinputvariablesarereceivedfromthemanualinputortheinputfromtheinjectionmouldingsimulation.Withtheoutp