RIM is the acronym for Reaction Injection Molding. RIM was developed in the 1960’s by Bayer AG as an alternative to thermoplastic injection molding.
RIM is a process where two liquid materials, Polyol resin and Isocyanate are brought together in a mix head and injected into a single or multi-cavity CNC machined mold. These two materials undergo an exothermic (heat generating) chemical reaction within the mold into the specific shape tooled into the mold and become the thermoset material Polyurethane.
Polyol resins also known as the “B-Side” or “Poly” are numerous due to the different requirements of each RIM part. Polyol’s create the physical characteristics of each part with additives that contain fillers like RRIM (Reinforced Reaction Injection Mold) and SRIM (Structural Reaction Injection Mold).