Fast Prediction of Crystallinity in Injection Molding during the Packing Stage

Being able to predict products’ degrees of crystallinity, and thereby optimize their crystallization processes, is of great significance for producing high quality polymeric products in injection molding. Injection molding simulation software can simulate polymers’ density results during the packing stage, and these predicted density results can be used to calculate polymers’ crystallinity results. Based on this idea, a novel method was proposed to predict the degree of crystallinity for polymers during the packing stage. For this method, pressure and temperature results were first simulated using injection molding simulation software, and then the density results were calculated based on a pressure–volume–temperature (PVT) model. Next, the crystallinity results were solved according to the densities of the fully crystalline part and the purely amorphous part. Finally, a real part in production was conducted as a case study to verify the proposed crystallinity prediction method. Experimental results showed that the proposed method was both correct and effective.