Injection Molding-Injection MoldingProcess Descriptionver. 11ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Overview• Equipment• Process2ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009ExtruderExtruder3ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Extruder and dieExtruder and die4ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Injection molding machineInjection molding machineClMldBlClampMoldHopperBarrel5ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009KrausMaffei at Ford4000 tonnesKrausMaffei at Ford -4000 tonnes6ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Injection molding machine schematicjg7ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Mold8ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009MoldMold9ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Modular moldsModular molds10ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Mold schematic11ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Mold schematicspruerunnercavitygatesprue nozzlepsidefrontejectionpin12pinME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Process13ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009ProcessProcess•Pellets placed in hopperPellets placed in hopper• Pellets fall into barrel through throatPllt kdt f lidbd•Pellets packed to form solid bed– air forced out through hopper• Pellets melted by mechanical shear between barrel and screw14ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009ProcessProcess•Melted plastic forms shot in front of•Melted plastic forms shot in front of screwbk lti–screw moves back as plastic moves forward (reciprocating screw)15ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Process• Screw moves forward to inject plastic jpinto mold cavityP t l d lidifi•Part cools and solidifies– next shot is made16ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009ProcessProcess•Mold opens•Mold opens• Ejection pins move forward to eject part• Mold closes•Process starts again•Process starts again17ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Feed zoneSolid bedFeed zone -Solid bed•Pellets crushed together•Pellets crushed together• Air ejected18ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Compression zoneMeltingCompression zone -Melting•Solid bed melted by mechanical shear•Solid bed melted by mechanical shearbarrelbarrelscrew flightsolid bedsecondarymixing flowscrew flight19ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Metering zoneHomogenizationMetering zone -Homogenization• Melted polymer is homogenized thermally and color-wise.y20ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Injection pressureInjection pressure• Typically 15,000 psi•Ranges from 3 000 to 40 000 psiRanges from 3,000 to 40,000 psi• Hydraulic pressure is about 10x less21ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Process timeClose moldInjectionOpen and eject partjp153335Part coolingPack and hold1522ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Pressure historyyMold closed timeCycle time50jectionCoolingMold closed time2st closingInjectionPackze offPart ej25FasGate freez33 3515500Time (s)23Time (s)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Temperature historyTemperature historyCooling200jectionpart100st closingnjectionPackze offPart ejpgateFasIGate freez33 3515500Time (s)24Time (s)ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009Gates and freezeoffGates and freeze-offFilling &PackingCooling25ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 2009SummarySummary• Equipment• Process26ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT 200927ME 6222: Manufacturing Processes and Systems Prof. J.S. Colton © GIT
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