Numerical Simulation of Powder Injection Moulding (PIM) Process of Metal-Loaded Polymers Into a Shallow Cavity

摘要

To improve the understanding of the rheology of a metal-loaded polymer, a computer program which simulates the powder injection molding (PIM) process has been developed and its output has been compared to actual laboratory experiments. Feedstocks based on polyethylene and paraffin wax binder have been prepared with four different powder loadings of high-speed steel (HSS M2) within 50% and 70% in volume. Assuming that the mixture is homogeneous and the mold is shallow enough, Hele-Shaw equations have been used to model the flow on a 6 nodes triangular finite elements mesh with quadratic interpolation. Coupled thermal and mechanical effects are numerically solved and the wave-front dynamics is tackled using the volume-of-control technique. Measured viscosity curves and other experimental rheological data are given as input to the program. Injection pressure and cavity-filling times predicted by the model are compared to actual experimental values for different feedstock samples. These results are used to validate the model and to determine its limitations.