understanding selection of injection moulding machin1

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1、UNDERSTANDINGSELECTIONOFINJECTIONMOULDINGMACHINEINTRODUCTIONPlasticInjectionMouldingprocessdemandsprecisecontrolofmelttemperature,meltviscosity,injectionspeed,injectionfollow-uppressure,switchoverpointfromspeedtopressure,cycletime.Itisfoundthatdifferentpolymershavedifferentcharacteristicsanddiffer

2、entlimitationsinprocessing.Shearrateandshearstressinfluencemelttemperature,viscosity,densityandflowbehaviorofpolymer.Somepolymersarehygroscopic,somepolymerhavelimitedthermallystabletimewhichisdifferentatdifferenttemperature.Suchpolymershavelimitedresidencetime.Thechangesineachparameterhasitsowninf

3、luencesonotherparameters.Hence,processcontrolbecomesveryintricate.Thiscallsforcriticalanalysisofthemachinespecificationsandcapabilitieswhileorderingthemachine.Whileselectinginjectionmouldingmachinethefollowingspecificationsarerequiredtobeevaluated.INJECTIONUNITTounderstandMaximumsweptvolumecc/max.

4、shotweightgr.calculationofmax.shotweightforamaterial.Maximummeteringstrokeinmm.dependanceofqualityofmeltforconsistancyofmoulding.Maximuminjectionspeedg/sorcc/showitensursmelttospreadthroughoutwheninfluidcondition-beforeitfreezes.Itsrelationshipwithfreezingtime.MaximuminjectionpressureKg/cm2howitov

5、ercomesresistancetoflowduringfillingand;pressurephaseonaccountofflowratioand;viscosity.MaximumInjectionPower.Kgcm/sec.howittakescareofdifficultyinfiilingforthinerwalledandhighflowratioparts.Plasticizingrateg/sorKg/hr.howitinfluencescycletime.CLAMPINGUNITTounderstandClearancebetweenTiebarsandplaten

6、sizemmxmmhowitaccomodatesmould.Maximumdaylightmmandmouldopenstrokemmitssignificanceforejectionofdeepparts.Minimummouldheightitsrelationshipwithmouldopenstrokeanddaylight.Clampingforceitsdependanceoncavitypressureandmethodtocomputecavitypressure.HYDROMOTORToubderstandTorqueKgmandrpmtorquerequiremen

7、tfor-viscosityof-melt.DRIVEPOWERPowersupplyfrquency60or50Hz.itsinfluenceonspeeds.Pump-motorrating.kWtomatchtheapplication-usageofmachine.CONTROLS·Conventional/ProportionalandCartridgevalveHydraulicControls·Electr