Injection Molding - MIT

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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 3Ref Kalpakjian and SchmidMcCrum, Buckley, Bucknall4OutlineBasic operationCycle time and heat transferFlow and solidificationPart designToolingNew developmentsEnvironment530 ton, fl oz (45 cm3) EngelInjection Molding Machinefor wheel fabrication6Process & machine schematics** Source: *Schematic of thermoplastic Injection Molding machine7Process OperationTemperature: barrel zones, tool, die zonePressures: Injection max, holdTimes: Injection , hold, tool openingShot size: screw window8Typical pressure/temperature cycleTime(sec)Cooling time generally dominates cycle timeTime(sec)* Source: **9Calculate clamp force, & shot sizeF=P X A = 420 lbs = 2245 cm3=75 ozActual ; 2 cavity 800 ton10Clamp force and machine costBoothroyd/Busch11Heat 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 temperatureqxqx+ DqxFourier s law12Heat transferTWTiitx+L-LLet Lch= H/2 (half thickness) = L ; tch= L2/a ;DTch= Ti TW(initial temp.)

Flow and solidification Part design Tooling New developments Environment 5. ... Similar to an injection molding machine, but without a mold and continuous production. Thus it has a similar energy consumption profile. ... Thiriez et al, "An Environmental Analysis of Injection

  Analysis, Flows, Injection, Molding, Injection molding