The aim of this study is to assess the effects of different parameters of the injection molding process in warpage, shrinkage, and mechanical properties of the plastic parts using the Taguchi method and the Analysis of Variance (ANOVA). The polyacetal copolymer (POM) and acrylonitrile-butadiene-styrene copolymer (ABS) were injected; and then the following processing parameters were analyzed: the mold temperature, holding pressure, holding time, melt temperature, cooling time, mold water flow, and injection speed. According to the results, statistically the most significant parameters in shrinkage were the mold temperature and cooling time for the POM molded parts; and the holding time and holding pressure for the ABS molded parts. The most significant parameters in warpage and flexural strength were the holding time and holding pressure for the POM and ABS parts, respectively. A multiple linear regression analysis was carried out to predict a theoretical ideal experiment to maximize the results.