Investigation On The Mold Filling Process In Powder Injection Molding Based On Granular Model

The homogeneity of injection molded parts is the key to a high yields in powder injection molding technology. Simulation of the mold filling process is a feasible way to solve the problem. Simulations based on continuum model or dry granular model are incapable to describe the process.The present work investigated the mold filling process based on wet granular model, a model more accordant with the actual filling process was established. The contact force model of particles where interstitial power law fluids fills were established, it is applicable to describe the movement of powder clusters in powder injection molding. The solving of the contact force model and simulation of the filling process was carried out by Matlab. Effect of parameters on the front motion of molding filling process and the homogeneity of the particle distribution were simulated. Experiments were carried to verify the simulation.The results of the front motion of molding filling process show that the higher injection velocities, the larger powder sizes, the higher temperature and the lower powder loadings cause the faster filling velocity. The results of uniformity show the higher injection velocities, the larger powder sizes and the lower injection temperature cause asymmetry, the most maximum difference is8%, close to the experimental results7.05%. And the result of the cavity with a step show the higher injection pressure cause uniform. The experiments show the difference of powder volume fraction from8.5%to0.4%with the increase of injection pressure. The results show good agreement with the simulation, proving that the model is able to predict the homogeneity of the mold filling process.