In injection molding, a hardened produt is obtained by injecting a heated melt of plastic resin into a metal mold and cooling it in the mold. Differences in shrinkage ratio can occur when the resin hardens in the mold, yielding products that depart greatly from their target dimensions. Whereas past evaluations were carried out by comparing actual products with their blueprint dimensions,in this study we evaluated transferability of the mold dimensions to a test piece. As a result, we were able to reduce point-to-point variations in shrinkage. To minimize measurement error, we also studied the optimization of a measuring method using a non-contact three-dimensional image measuring instrument.
