5. Interest

Not counting the performance of polyurethanes (the first polymers transformed by the RIM process for the manufacture of automobile bumpers, the only ones capable of meeting the American specifications of the 1970s), the RIM process offers numerous advantages over the two other competing manufacturing methods:

• injection molding of thermoplastics ;

• compression of thermosetting materials.

• The RIM process enables large parts to be produced on presses with low clamping force.

  For a polyurethane bumper, the clamping force required for the presses supporting the molds is around 100 to 200 tf (1 to 2 MN), whereas for polypropylene injection molding, presses of 2,000 to 2,500 tf (20 to 25 MN) would have to be installed.

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