Reaction Injection Molding (RIM) produces parts with complicated detail that are dimension-ally stable, chemically resistant, physically tough, and wear resistant. This process is an good choice for larger plastic parts produced in short run or low volume production quantities.
The process takes its name from a chemical reaction that occurs within the tool. The plastics used are thermosets, either polyurethanes or foamed polyurethanes. The two components that produce the polyurethane are mixed just prior to injection into the tool. With the low viscosity and low injection pressures, large, complex parts can be produced economically in low quantities.