The influence of cavity deformation on the shrinkage and warpage of an injection-molded part
As soon as the gate solidifies or the nozzle is closed, the amount of melt inside a cavity remains constant. At this moment, the cavity deformation affects the final product shape and size. A set of simulation procedures has been developed in this study to estimate the cavity deformation which arises during an injection-molding process. A mold-filling program was applied to calculate the molding variables. The estimated cavity pressure, temperature distribution, and clamping force were employed as the boundary conditions in the mold-deformation analysis. A structural analysis program was developed to predict the cavity deformation. Molding experiments were carried out for polymethyl methacrylate (PMMA) wedge-shaped parts. To verify the structural analysis, a strain gauge was installed on the sidewall of the mold. The measured strains agreed with the simulated results. A commercial simulation software package was also used to predict the shrinkage and warpage of injection-molded parts. Numerical results showed the improvement in predicting the shape and size of a final product by taking the cavity deformation into account. The influences of the packing pressure, mold temperature, or melt temperature on shrinkage and warpage were also investigated.
KeywordsInjection molding Shrinkage Warpage Deformation
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