Numerical simulation of filling stage during injection molding

Abstract

In order to accomplish injection molding process effectively and to eliminate the need for costly iteration of mold design and tooling, analysis of the filling stage is essential. For complex problems, numerical methods are commonly used for modeling of the filling process. With development of CAD/CAM, numerical methods are widely used for simulation of the injection molding process which is one of the important net shape manufacturing process. Numerical and experimental investigations on injection molding of ceramics and general purpose polymers were carried out. The mold filling process was studied for mixtures of a ceramic material and the selected binder system. A pure polymer was also considered for comparison. Rheological behavior of the ceramic mixture was examined and applied to numerical simulation. Good experimental and numerical results were obtained for tensile and bending specimens and a turbo-charger rotor blade. For better the implementation of numerical analysis, a delivery system was considered by employing tubular elements and three dimensional geometry was modeled easily with coordinate transformations without layflat approximations. To show the effectiveness of the developed program, pressure and mold wall temperature distributions were measured by pressure transducers and thermocouples and the results were compared with simulations. It has been shown that results of the experiment and the simulation are in good agreements with respect to melt fronts and pressure profiles. In this study, a hybrid finite element/finite difference control volume method and an automatic mesh generation scheme for arbitrary three dimensional thin cavity were developed and applied to numerical simulation of filling process in injection molding. A flow analysis program for mold filling which has been running on a work station and PC was developed successfully. The developed program provided useful information on flow front advancement, pressure profile, weld line ...