Engineering Analysis for Plastic Molding Quality Assurance and Productivity

Abstract

The injection molding process has been widely used to manufacture various plastic products featuring complex geometry. Product quality and productivity are conflicting requirements which are hard to achieve simultaneously. Some molding simulation packages are available which can accurately simulate the injection molding process based on process parameters, material data and mold configuration, and can help engineers to understand the molding process and evaluate the quality of the parts. However, due to the complexity of the molding process, producing high-quality plastic parts in less cycle time is still difficult, even with the help of advanced simulation technology. This thesis analyzes the gaps between the real injection molding process and the current available technology, and proposes a finite element analysis method to ensure that high-quality plastic parts are produced in less cycle time. First, a simulation workflow is proposed that aims to analyze the causes of warpage after pilot molding, and four possible methods are suggested to resolve such problems. Next, a molding simulation and structural analysis integrated method is proposed to predict the ejection-induced deformation and the shrinkage resulting from air-cooling. Finally, a new mold design strategy is proposed to facilitate early ejection upon partial solidification. By accurately predicting the molding behavior of plastic parts throughout the molding process, the parts, the mold and the process itself can be better designed to ensure the quality of plastic parts in less cycle time.