An airflow intake manifold cast using polyurethane is tough enough for testing on operating engines.
An airflow intake manifold cast using polyurethane is tough enough for testing on operating engines.

The ability to cast prototypes in polyurethane has led Rapid Prototype Co., Auburn Hills, Mich. (www.rpparts.com), to make air-intake manifolds and short-run parts in the material. RenPIM 6460 polyurethane comes from RenShape Solutions Tooling Group of Huntsman Advanced Materials, East Lansing, Mich. (www.renshape.com). It can be cast in silicone rubber molds and is said to provide polypropylenelike performance with a quick 15 to 30-min demold time.

The polyurethane features a Shore hardness of 80 D, a flexural modulus of 181 kpsi, notched Izod impact strength of 1.1 lb-ft/in., elongation of 8%, and a heat-deflection temperature of 282°F. "It's easy to shoot with a relatively long gel time that works well for casting large parts," says Ralph Weil, general manager of Rapid Prototype. "It also features the durability we need," he adds.