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What Is Reaction Injection Molding?

October 18, 2015

RIM body panels

Reaction Injection Molding (RIM) uses low-viscosity liquid polymers in thermoset processes. As a result of chemical reactions, the polymers expand and they become thick and hard after being injected into the heated mold under high pressure using an impinging mixer. Reaction Injection Molding produces strong, durable yet flexible, lightweight parts that are easily painted. When compared to vacuum cast materials, RIM has the upper hand because of quick cycle times. The biggest advantage to RIM is that the large polyurethane parts are made much lighter without compromising strength, flexibility, or durability.

The RIM manufacturing process involves polymer liquids that are stored in large tanks and dispensed by large, high pressure pumps. The polymers are recirculated from the tanks to a multi-stream mix-head on the machined aluminum mold, and back to the storage tanks in a continuous loop. When each part is manufactured, a piston retracts inside the mix-head, which breaks the loop. The polymers then mix at extremely high velocity to ensure proper mixture. When compared to injection molding, vacuum forming, pressure forming, and cast molding, RIM is superior.

While RIM is a longer process than others designed to achieve similar results, the outcome is worth the wait. Quite simply, it is the most advanced process for polyurethane parts manufacturing. Whether you are in the transportation, heavy truck manufacturing or servicing, agriculture/construction, or the spa industry, parts manufactured through the RIM process can be an asset to your business.

At Romeo RIM, we have created parts through the RIM process for more than 30 years. As the 2014 AGCO Quality Award recipient, we have been recognized for our outstanding services. We have expanded our RIM technology capabilities over the years and have introduced our products to new markets with great results. If you are interested in learning more about the ways our business can help yours, contact us and request a quote today!

Romeorim design guide