Injection Molding - MIT

Injection GutowskiD. Roylance1V-6 air intake manifoldWater control valveBrass Vs Injection history of plastics1866 Celluloid1891 Rayon1907 Bakelite1913 Cellophane1926 PVC1933 Polyethylene1938 Teflon1939 Nylon stockings1957 velcro1967 The Graduate 1970 Earth Day recycling 3 Ref Kalpakjian and SchmidMcCrum, Buckley, Bucknall4 OutlineBasic operationCycle time and heat transferFlow and solidificationPart designToolingNew developmentsEnvironment530 ton, fl oz (45 cm3) EngelInjection Molding Machinefor wheel fabrication6 Process & machine schematics** Source: *Schematic of thermoplastic Injection Molding machine7 Process OperationTemperature: barrel zones, tool, die zonePressures: Injection max, holdTimes: Injection , hold, tool openingShot size: screw window8 Typical pressure/temperature cycleTime(sec)Cooling time generally dominates cycle timeTime(sec)* Source: **9 Calculate clamp force, & shot sizeF=P X A = 420 lbs = 2245 cm3=75 ozActual ; 2 cavity 800 ton10 Clamp force and machine costBoothroyd/Busch11 Heat transfer Note; aTool>apolymerBoundary Conditions:1-dimensional heat conduction equation :The boundary condition of 1stkind applies to Injection Molding since the tool is often maintained at a constant temperatur

Effects of mold temperature and pressure on shrinkage 0.030 0.000 0.010 0.005 0.015 0.020 0.025 100 120 140 160 180 200 220 240 Mold Temperature (F) LDPE PP Nylon 6/6 PMMA Acetal age 0.030 0.000 0.010 0.020 0.025 age 6000 8000 10000 12000 14000 16000 Pressure on injection plunger (psi) Acetal LDPE Nylon 6/6 PP with flow 18000 PP across flow PMMA 24

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  Injection, Molding, Mold, Injection molding

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