Improving appearance quality of injection molded microcellular parts through mold coating of <scp>PTFE</scp> and zirconia

Abstract

Abstract The application of microcellular parts in the field of high appearance quality is limited due to its appearance defects. In order to improve the appearance quality of microcellular parts, low heat transfer coefficient mold coating with PTFE and zirconia was employed in this study. The appearance quality of microcellular was evaluated by the surface roughness of microcellular parts. The numerical and experimental results show that delayed heat transfer between the melt and the mold can be achieved through both mold coatings, which improve the melt fluidity and reduce the shear force of the mold on the melt effectively. It is demonstrated that the PTFE has a better effect of delay heat transfer under thinner coating. The polished zirconia coating shows more conducive to the melt wall slip due to its stable molecular structure and smooth surface, resulting in microcellular parts with better appearance quality.