Numerical Simulation and Experimental Study of Warpage of Injection-Molded Parts

Abstract

: The accurate prediction of warpage of injection-molded parts is important to achieve successful mold design and processing parameters settings with high precision. A numerical simulation model for predicting residual stress and warpage that arise during the injection molding of thermoplastic polymers in the packing and cooling stages has been developed. A thermorheologically simple viscoelastic model was used for the calculation of residual stress. The finite element method for warpage simulation was based on the theory of shells as an assembly of flat elements that are formed by combining the constant strain and the discrete Kirchhoff triangular element. This theory is well suited for thin injection-molded products of complex shape. Experiments on a flat plate were also carried out to study the effect of processing parameters on warpage. The simulation results were also compared with the experimental data for verification of the developed program. It was found that the predictions were in agreement with experimental data, especially in qualitative analysis.