EFFECTS OF MIXING CONDITION ON THE FEEDSTOCK PROPERTIES FOR MICRO SIZE PARTS BY MIM

摘要

Producing micro size parts by Metal Injection Molding (MIM) needs more sophisticated technique than the conventional injection molding. Especially, inhomogeneous state of feedstock will strongly influence on the quality of the final products. In order to evaluate the mixing and pelletizing conditions of the feedstock, we focused on the unit of pellet. In this study, statistical variations of density and binder contents in individual pellet were investigated by the weight measurement of both as-received feedstock and sintered one. The micro dumbbell specimen was fabricated using the feedstock, and was compared to the feedstock concerning the variations of some physical properties. These variations were discussed with coefficient of variation and Weibull's shape factor. From the experimental results, it was found that the variation of mixing and pelletizing on the pellet scale affected on that of micro-dumbbell sintered specimen. Moreover, re-pelletizing of pellets was conducted for improving the homogeneity of feedstock, and the effect on the reduction of variation was demonstrated.