Warpage comparison between microcellular and conventional injection molding

This research investigated the effects of processing conditions on the shrinkage and warpage (S&W) behavior of a box-shaped part using conventional and microcellular injection molding. Two sets of 2 ^6-1 fractional factorial DOE were employed to perform and analyze the experiments. After the machine and material reached the steady state condition, molded samples were collected and measured using an optical coordinate measuring machine (CMM). The results suggest that the supercritical fluid (SCF) content (in terms of SCF dosage time) and the injection speed affect the S&W of microcellular injection molded parts the most, whereas hold pressure and hold time have a greater influence on the S&W of conventional injection molded parts. This study also quantitatively showed that, within the processing range studied, an increase in dimensional stability could be achieved with the microcellular injection molding process.