Analysis and sensitivity analysis for polymer injection and compression molding Original Research Article

Polymer process modeling, design sensitivity analysis, and numerical optimization are combined to design processes for the manufacture of plastic components via the injection and compression molding processes. The Newton-Raphson iteration is used to solve the nonlinear equations for the polymer melt pressure field which are formed via the isothermal Hele-Shaw flow analysis and Galerkin finite element method. To compute the fill time and filling pattern, a moving boundary analysis is developed based on the volume-of-fluid (VOF) technique. Design sensitivities for the transient coupled pressure and volume fraction analyses are evaluated using the direct differentiation method. The molding analysis and sensitivity analysis are combined with numerical optimization to design, not just analyze, the injection and compression molding processes. Examples illustrate the polymer processing design methodology where the injection molding process is designed to minimize mold fill time and satisfy constraints on injection flow rate and mold clamp force.