RIM Mold and injection molds have many differences in the same method as most engineers and designers - unlike injection molding, RIM techniques use thermoplastic non-thermoset low-viscosity liquid polymers. Through various chemical reactions, these polymers thicken and harden only after being injected into the heated mold and contain much more complex designs than ordinary injection molding. The raw materials and molding techniques can be selected and even customized to provide the desired weight, strength, density and hardness properties precisely.


Because liquid polymers require less pressure (~ 100 psi) and lower temperatures (~ 90 °) than typical components, they are injected into low-cost aluminum molds, reducing the mold costs used. The molds are moderately heated (~ 190 °), but the resulting exothermic reaction quickly brings the materials ~ 325 ° and immediately cures the portion inside the mold. Depending on the size, geometry, function and wall thickness of the piece, the curing process can range from one minute to several minutes.

RIM Molding

The RIM production process begins with polymer fluids (polyol and isocyanate) stored in large storage tanks and distributed by large, high-pressure industrial pumps. The polymers are recycled from storage tanks to a multi-flow mixing head on a machined aluminum die and to storage tanks in a continuous cycle.

When each part is made, a piston inside the mixing head is withdrawn, interrupts the continuous cycle, and the polymers then mix at a high speed - about 1200 psi - to provide a suitable mixture of polymers. The resulting polyurethane reduces the pressure of the mixer to 95-100 psi.

Reaction Injection Molding (RIM) offers not only significant advantages over injection molding, but also vacuum forming, pressure forming and casting molding.

Compared to the advantages of the long production time of injection molding, the width of the part size, the uniqueness of the design, RIM molding provides advantages in design, flexibility and low cost.


REACTION INJECTION MOLDINGLess Piece End User Part for your needs, 50-200 pcs
Functional part requirements
In the manufacture of bumpers, torpedoes and large-sized closures
Products requiring functional and mechanical testing