Optimizing injection molding parameters to reduce weight and warpage in PET preforms using Taguchi method and Analysis of Variance (ANOVA)

Abstract

Plastic injection molding is widely utilized for the production of a variety of plastic products. However, defects can arise during the production process due to incorrect settings of process parameters, which are crucial for ensuring the quality of the molded parts. In the injection molding industry, key concerns include the strength, warpage, and weight of the molded components. This article presents an experimental design technique aimed at minimizing warpage and weight in Polyethylene Terephthalate (PET) preforms weighing 45 g. The experiments were conducted at the Continental Plastic Industry in Lahore, Pakistan. Five significant process parameters were identified through preliminary screening: cooling time, cycle time, melting temperature, injection time, and molding temperature. The experiments were conducted using the Taguchi L₂₇ (3^5) orthogonal array design. The analysis of variance (ANOVA) and signal-to-noise (S/N) ratio were employed to identify the optimal parameter levels and evaluate their effects on warpage and weight. The results indicated a reduction in warpage by 4.75 % and weight by 2.05 % under the optimal settings. A verification test confirmed the effectiveness of the Taguchi method at the optimal parameter levels, ensuring consistency with the experimental findings. The practical implications of this study are substantial. The reduction in warpage and weight achieved through optimized parameters leads to improved product quality, material efficiency, and cost savings in the manufacturing process. Furthermore, the decrease in plastic usage aligns with environmental sustainability goals by minimizing waste and conserving resources.