Stress analysis of a large diameter aspheric plastic lens in the variable temperature assisted injection molding process

The technology known as precision injection molding (PIM) has shown great promise in the large-scale manufacturing of optical plastic lenses. The primary challenge with the PIM process is accurately predicting and reducing residual stress in optical plastic lenses. In this work, the finite element method (FEM) was used to analyze the residual stress distribution in plastic lenses. A three-dimensional model was created using COMSOL software to investigate how residual stress and temperature varied in optical plastic lenses during the packing and cooling stages. Based on the results, variable temperature assisted injection molding experiments were conducted. The results show that the average residual stress in the optical plastic lenses has decreased by 56%, while the minimum and maximum residual stress levels have decreased by 60% and 61%, respectively. Since this method does not require the extra heat treatment of the optical lenses, it offers considerable cost and efficiency benefits.