Critical Powder Volume Concentration (CPVC) of Fe-2Ni low-Alloy Steel Powder and Selection of a Proper Binder System from Rheological Point of View in order to Metal Injection Molding

Metal Injection Molding (MIM) is a novel manufacturing technology, used for complex geometric parts at a high production rate. One of the most important parameters in this method is the selection of proper feedstock consisting of optimal powder loading and an optimized binder system. The defects, which appear during the injection process, cannot be removed in later process stages and this is for the reason that the rheological behavior of the feedstock needs to be checked to make sure that it has the required injection properties. In this study, a multi-component wax-based binder system has been selected in order to inject Fe-2Ni powder. For this reason, a multi-component wax-based binder system with different percentages of constituents was used to produce 11 feed modes containing 60% vol. % of the powder. Further, the viscosity and its variation with the shear rate for 11 developed samples have been measured. The results showed that the feedstock consisting of 66 vol. % Paraffin wax, 19 vol. % Polypropylene, 10 vol. % Carnauba wax and 5 vol. % Stearic Acid has the lowest viscosity and lowest sensitivity to the shear rate and this leads to the complete filling of the mold cavity and production of a healthy component for very complex geometries. After achieving the proper binder system, the critical powder loading for the binder system was measured by 58 vol. % using torque rheometer.