Reaction injection molding
From Plastics Wiki, free encyclopedia
RIM (Reaction Injection Molding) Involves the injection of liquid polyurethane systems into a mold. The components then polymerize within the mold. Typically, this low temperature process typically takes less than a minute to complete, including time for mixing, curing, and demolding.
This technique is a form of liquid injection molding (LIM). When short fibers (1.6 mm), carbon or mineral fillers are incorporated into one of the liquids to increase modulus and reduce coefficient of expansion the process is referred to as reinforced reaction injection molding (RRIM). RIM resin systems include epoxy which mold over continuous strand mat and preforms as well as polyurethane/polyester hybrids, polyurea and poly(DCPD).
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Raw Materials
Liquid urethane in various combinations with liquid catalyst
Tooling
Machined steel or aluminum; cast aluminum.
Cost
Parts & tooling relatively high.
Advantages
Strong, flexible, lightweight parts which can easily be painted.
Disadvantages
Slow cycles, expensive raw materials.
Applications
Automotive spoilers, interior trim panels for automobiles and trucks.
Process: Injection molding cycle Reaction injection molding, Reinforced reaction injection molding, Liquid injection molding, Gas assist injection molding, Coinjection molding, 2-Shot Injection Molding, Fusible core injection molding, Rapid injection molding, Micro injection molding
Equipment: Injection molding machine, Injection molding press, Injection mold (Hot runner, Cold runner), Injection unit (Injection ram, Injection screw), Clamping unit (Toggle , Hydraulic, Hydromechanical), Plunger injection molding, Injection molding manufacturers
Terms: Injection pressure, Injection rate, Clamping pressure
See also: Plastic thermoforming • Blow molding • Plastic welding • Plastic extrusion • Rotational molding
