Unlike thermoplastic injection molding, Reaction Injection Molding is a process capable of achieving a broad range of properties. While both processes use molds to form parts, the RIM process uses polyurethanes to produce molded parts.
The RIM Process
The polyurethanes are two liquid components (Polyol and Isocyanate) developed in two-part formulations to create RIM systems. The system will determine whether the part molded will be a foam or a solid and whether the part will be flexible or extremely rigid. The specific gravity will range from 0.2 to 1.6.
The RIM Process involves a chemical reaction between the two liquid components. Initially, the liquids are held in separate, temperature-controlled feed tanks. The chemicals are fed through supply lines to metering units that precisely meter both chemicals, at high pressure, to a mixhead device.