Prevent weld line defects on an automotive crash pad by local heating and cooling with 3D printed insert core

A 3D printed insert core, which embeds a heater and cooling channel by additive manufacturing, can lead to conformal heating and cooling on the vicinity of the defect area in the injection molding process. The purpose of this study is to design a 3D printed insert core of an injection molding tool to reduce weld line defects on automotive crash pads with a high standard of appearance. In this study, heat transfer experiments were conducted to compare the efficiency of two different types of building up method for insert core. A heat transfer simulation was conducted to design a heater and cooling channel for the conformal surface temperature of the insert core and for thermal response efficiency. The Taguchi optimization technique was used to investigate the influence of the heater and cooling channels design parameters on the surface temperature during the heating and cooling stage. The effects of the insert core surface temperature to eliminate the weld line defects were evaluated by a series of injection molding experiments for manufacturing the automotive crash pad. The results of the experiments indicate that the developed 3D printed insert core can greatly improve the uniformity of the surface temperature in the defect area and reduce the weld line of the manufactured product.