Reaction Injection Molding (RIM) is a manufacturing process applicable to producing complex, lightweight, and durable polyurethane (PU), epoxy, and silicone thermoset solid and foam parts.

The reaction injection molding (RIM) process utilizes low-viscosity liquid polymers. These polymers expand and thicken through a variety of chemical reactions. After the polymers have been injected into the heated mold they eventually harden.