Class-A Structural RIM: Report on a Program to Develop SRIM for Exterior Automotive Body Panels

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.