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A structural RIM (SRIM) bumper beam has been prototyped which is able to withstand 5 m.p.h. pendulum and barrier impact requirements without an additional energy absorber (EA). The performance level of this beam is due to a novel design, a high-elongation resin system, and a directed chopped fiber (DCF) preform. The behavior of this advanced bumper beam is contrasted with the Dodge Viper SRIM bumper beam which utilizes an expanded polypropylene (EPP) energy absorber. The new prototype beams reduce the cost and weight of SRIM bumper systems.

Historically, structural reaction injection molding (SRIM) has been restricted to use in non-appearance applications because of problems with glass “read-out” and surface porosity. In this experimental work, a SRIM resin was developed which provides a Class-A surface on an automotive hood after passing through production bonding and painting conditions. The surface quality of production bonded and primed SRIM hoods was measured using LORIA* and D-Sight ** surface analysis techniques. The performance of bonded SRIM hoods was measured by way of stiffness and torsional rigidity tests. The physical and mechanical properties of test specimens taken from SRIM hood parts were measured. An approach for recycling SRIM hoods was proposed. In addition to achieving high surface quality, the goal of this development effort was to produce lightweight, cost-competitive Class-A SRIM parts.

SRIM (structural reaction injection molding) has been restricted to non-appearance parts because of problems with glass “read-out” and surface porosity. Development work undertaken by Miles Inc. has focused on improving SRIM surface quality by means of tooling, reinforcement, and processing. An SMC (sheet-molding compound) Fiero hood outer tool has been modified for use with our SRIM center-gated injection process. The surface quality of SRIM Fiero hoods painted with a glossy black polyurethane coating has been characterized in terms of distinctness of image (DOI), long-term distortion, and short-term waviness. In addition to achieving high surface quality, we have been able to produce lightweight, cost- and performance-competitive Class-A SRIM parts.