Injection Overmolding of Continuous Carbon Fiber Preforms

Abstract

This project explored and developed a process to injection overmold continuous carbon fiber preforms fabricated with tailored fiber placement. Much early work was focused on the ability to infuse dry carbon fiber tow, fully wetting out the fibers, in an injection molding process. Various approaches were explored, including using commingled fiber and pre-consolidated flexible preforms. The commingled fiber was a blend of carbon fiber and polymer fiber matching the injecting polymer. This approach showed some merit but required an extremely high quality homogeneous mixing of the polymer fibers with the carbon fibers to wet out the carbon fiber tow. Therefore, the project focused on pre-consolidated preforms. The pre-consolidated preform manufacturing method was first developed using compression molded flat plates that were cut into tensile specimen for testing. Work then progressed to an injection molded simplified corner fitting bracket. It was shown that a viable manufacturing method for overmolding continuous carbon fiber preforms could be developed.