:The advantages of the injection/compression molding process for thermoset composite materials will be addressed as follows: 1) Thermoset composite history and transition of compression molding to injection and injection/compression molding processes. 2) Advantages of automated injection/compression molding to reduce labor, scrap rate and product cost. 3) Machine design requirements for efficient and consistent injection/compression molding. 4) Mold design examples will include moveable core pins to eliminate weld lines, gate-cutters used to balance flow, and other standard injection/compression concepts. 5) Current and future under-hood applications for thermoset composite materials. Design engineers in the automotive industry have been in the forefront of the accelerating movement toward replacing machined and cast metal parts with molded plastic parts. From the late 1970's, manufacturers have worked successfully to replace many exterior panels and body parts with compression-molded plastics, and these techniques continue to be developed and refined.By the early '80's, the search was on for ways to manufacture under-hood assemblies and parts of plastics, as well, and that journey is well under way. Industry-watchers predict that the '90's will be the significant decade for under-hood manufacturing breakthroughs. Why? Because a whole new generation of materials and sophisticated process technology are driving the research, and the industry demands faster production, higher quality parts, and lower manufacturing costs.Both Ford and GM experimented unsuccessfully in 1980 with injection molded nylon valve covers. The concept turned out to be sound, but the materials, at that time, could not provide the strength, long-term dimensional stability, and heat resistance that was needed.Today automakers are looking more and more to glass- reinforced thermoset materials to deliver properties that meet or exceed stringent under-hood standards - and offer additional advantages of noise reduction, lighter weight, and longer life. Most important, thermosets offer exceptional dimensional stability over a wide range of temperatures and long periods of time, which gives these materials an advantage over nylon.