The Numerical and Experimental Investigations of Injection Mold Filling and Determination of the Appropriate Conditions in Metal Injection Molding (MIM)

The most important steps in the metal injection molding (MIM) process are the design and manufacture of the injection mold. By far the most influential factors in the quality of the part are the injection site in the mold and how the part is filled during the injection molding, which directly affects the quality of the final part. In this paper, a powder containing 316L stainless steel is used as the raw material, and the Moldex 3D software is used for the simulations. The injection time, the cooling time, and the keeping time parameters are considered fixed for all tests with the values of 2.5, 10, and 2 seconds respectively. The speed, pressure, and temperature of injection are also considered as effective parameters. The boundary layer method (BLM) is used to simulate the process. The 3D model of the part is designed with three gate paths and different injection conditions. The injection mold is made for the optimized sample and produced under different conditions. Comparing the results of simulations with the experimental results shows the accuracy of the simulation results. The results also show that in the process of MIM, the injection fluid has a very high viscosity and different behavior compared to the similar fluid of the base polymer used in the feed. Besides, the optimal values for speed, pressure, and temperature of injection are found to be 60%, 60%, and 185 ° C, respectively.