Research on residual stress control in polycarbonate molding based on orthogonal analysis

Abstract Residual internal stress is a primary factor affecting the performance and quality of transparent food containers formed by polycarbonate injection molding. Adjusting the injection molding process parameters stands out as the most effective means to control residual internal stress. This study employs numerical simulation to analyze the influence of injection molding process parameters on material internal stress during the polymer injection molding process, providing a reference for optimizing molding process parameters. Initially, through an analysis of the mechanism of internal stress formation, it is determined that the internal stress of beverage containers is mainly composed of cooling internal stress. Consequently, a mathematical model based on thermo-viscoelastic constitutive relations is selected to numerically simulate and calculate the formation of cooling internal stress during the injection molding process of PC materials. Numerical simulation results are obtained accordingly. Building upon this, orthogonal experiments are conducted based on the analysis data from numerical simulation, and through experimental comparison, the consistency between numerical simulation results and experimental results is validated. Finally, combining the results of experiments with numerical simulation, it is concluded that melt temperature is the primary factor influencing molding internal stress, followed by mold temperature and holding pressure, with injection speed being the least influential factor on residual stress.