Reaction injection molding

Reaction injection molding (RIM) is a molding process to manufacture plastic molded parts.

Polyolefin and Isocyanides (as well as some other ingredients) are mixed in a mixing device in a fluid state and then injected as a liquid mass into a mold. The solidification of the liquid mass occurs in the mold as the mixed liquids react with the heated surface of the tool surface.

The advantage of this process is a low clamping force needed for the mold, long material travel paths and the low pressure conditions of the molding process. The necessary molds can be manufactured quickly and cost effectively using aluminium.

Molded parts produced in the RIM process compete with parts from injection molding, thermo forming and fibreglass lay up. The liquid masses of the RIM process have a more advantageous flow behaviour in comparison to injection molding due to the low viscosity of the material since they are not a thermo plastic. Therefore, much longer flow paths can be achieved with the same wall thickness than other traditional molding processes..

Thieme has been producing RIM plastic parts for more than 40 years.
Over 4000 different customer-specific parts have been realized by Thieme.

More about Thieme RIM


THIEME Corporation
3605 Swenson Avenue
St. Charles, IL 60174

Phone +1-630-513-1666
Fax     +1-630-513-1999