Mixing and characterization of feedstock for powder injection molding

Abstract Feedstock preparation for Powder Injection Molding (PIM) is a very crucial step since deficiencies in quality of the feedstock cannot be corrected by subsequent processing adjustments. Hence, it is important that the feedstock is homogeneous and free of powder–binder separation or particle segregation. The quality of the feedstock in the mixing process depends on numerous parameters such as mixing time, mixing temperature, sequence of material addition, powder size and shape, formulation of binder, shear rate, and powder loading. The present mixing study was conducted with 316L stainless steel and titanium carbide powders. The main objective was to establish suitable mixing parameters such as powder loading, mixing speed and mixing temperature. The rheological characteristics of the feedstocks, under various mixing conditions, were analyzed using the capillary rheometer. Results show that 54% volumetric powder loading gave satisfactory flow properties when mixed at a temperature of 90°C with a rotor speed of 30 rpm.