Evaluation of thermal contact resistance of molten resin–mold interface during high-thermal-conductivity polyphenylene sulfide filling in injection molding

Abstract

High-thermal-conductivity polyphenylene sulfide (PPS) has both mechanical and heat dissipation properties, and its low weight and fuel efficiency make it a suitable replacement for metals in automobiles. However, this resin often causes filling defects in the injection molding process. This is due to the higher thermal conductivity, which causes the molten resin to solidify more quickly during the filling process. Therefore, it is important to predict the cooling and filling behaviors of the resin accurately using computer-aided engineering (CAE). Currently, many commercial software programs use thermal contact resistance (TCR) as the thermal boundary condition between the mold and resin. However, there is no established method to accurately evaluate TCR during filling with high spatial resolution and response, and the accuracy of CAE cannot be maintained. Therefore, we used thermography and a prismatic glass insert mold to thermally visualize and analyze the filling process of this resin. Consequently, we succeeded in evaluating TCR values with high spatial resolution and response. The obtained TCR values varied depending on the flow state and pressure. To further validate the obtained TCR values, we compared “the visualization results of real flow conditions” and “the flow prediction results of CAE considering the obtained TCR values”.