Metal Injection Molding: The Rheological Study and Injection Molding of Feedstocks Based on Copper Powder and a Thermoplastic Binder

摘要

Recently metal injection molding (MIM) has been considered as an alternative in processing complex and near net shaped components besides reducing costs. This process consists of four steps: mixing of metal powders with a binder to prepare a feedstock, injection molding of the feedstock, debinding and sintering. In this work feedstocks prepared for injection molding were based on gas atomized copper powder, as metal component and a thermoplastic binder based on paraffin wax. Mixing was carried out in a Haake mixer and the rheological properties of feedstocks were investigated using a capillary rheometer. The optimum formulation 95/5 wt/wt (copper powder/binder) was obtained from rheological and debinding investigation. It was observed that the feedstocks were very temperature sensitive and showed a pseudoplastic behavior. The injection molding of the feedstocks was performed successfully.