Reaction Injection Molding of Automobile Bumper
  • Reaction Injection Molding of Automobile Bumper
  • 1. Project Description:

    Prototyping Process: Reaction Injection Molding (RIM)
    Tooling Material: Epoxy and Silicone Rubber
    Molding Material: Polyurethane Hei-Cast 8636-75A (Black) and Hei-Cast 8636-B
    Part Tolerance: ± 0.2/100 mm
    Quantity: 20 units
    Lead Time: 20 days

    Reaction Injection Molding material bi-component polyurethane has very low viscosity, so compared to conventional plastic injection molding process, the injection pressure and temperature of RIM process are both much lower, which results in lowering the tooling performance requirements, this greatly reduces the tooling fabrication cost and time. To effectively reducing this automobile bumper prototype manufacturing cost, the RIM tooling materials we used are epoxy resin and silicone rubber.




2. Project Key Points:

The correct amount ratio and complete mixing of the two liquid polymers in the mixing head are the key points that decide how quality the molded part is.

3. Reaction Injection Molding advantages:

Economical production cost and short cycle time. The low injection pressure and temperature of Reaction Injection Molding technique lower the tooling performance requirements, so the RIM tooling are normally made out of ABS, Epoxy and Aluminum, compared to the plastic injection mold, RIM tooling fabrication cost is just a fraction of PIM mold, meanwhile the tooling fabrication time is also much shorter. This allows for reducing the product development cost and time, and getting the product to market quicker.

Reaction Injection Molding China





Epoxy and silicone rubber RIM tooling
RIM parts






Different wall thickness on one part. Compared to the limitation of uniform wall thickness for conventional plastic injection molded part, different wall thickness on one part can be achieved by Reaction Injection Molding process, and the wall thickness can vary from 1 mm to 30 mm, so reaction injection molded part can better present the product’s design idea and style.
Strong strength and high temperature resistance. Reinforcing agent, normally glass fiber, can be added to the reaction injection molding material to increase the part strength, this process is called Reinforced Reaction Injection Molding that is suitable for making rigid structures or panels. Compared to vacuum cast part, the temperature resistance of RIM part is up to 120℃, much higher than vacuum cast one of normally 60-70℃.





Reaction injection molding factory
Insert molding. Because of the low injection pressure and temperature, the small assembly components can be first placed in the mold and then the polymer mixture is injected to the mold and meanwhile encapsulated the inserted components, this eliminates the assembly work also gets excellent sealing effect.

4. Conclusion:


Reaction Injection Molding process can produce large covering parts at low injection pressure since the material properties of very low viscosity and good flowability, and RIM parts have the characteristics of lightweight, high strength, different wall thickness on same part, no sink mark on thick wall thickness, so RIM process is widely used in the low volume prototyping and manufacturing of automobile bumpers, medical device covers and protective shells with big size and relatively simple geometry. Customers can benefit from our experienced, quick and economical Reaction Injection Molding services.

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