Influence of the contacting on the resistance heating of carbon fiber reinforced thermoplastics

Abstract

Particularly in the automotive industry, continuous fiber-reinforced thermoplastics are currently enjoying steadily rising demand. Thermoplastic matrix systems promise shorter cycle times and enhanced joining and recycling characteristics when compared to fiber reinforced thermosets. In order to process continuous fiber reinforced thermoplastics, semi-finished parts are produced first. These are heated and post-processed in a back injection molding process. Design elements such as load transfer elements and ribs are injected onto the flat semi-finished part. To heat the parts, the effect of Joule heating can be utilized. The electrically conductive carbon fibers are heated by an applied voltage. The temperature is distributed through heat conduction into the part's matrix. The use of Joule heating enables high heating rates with low energy consumption. The industrial application of Joule heating of continuous fiberreinforced thermoplastics requires the specification and investigation of further relationships between the influencing variables. The quality of the heating is significantly influenced by the contacting of the part. Within the scope of this study, heating experiments are compared using a thermographic image system. It is found that higher contact areas yield better heating quality and that rounded corners for the contact pieces additionally improve the temperature distribution.