Low-pressure powder injection molding (LPIM) is a cost-effective technology for producing intricate small metal parts at high, medium, and low production volumes in applications which, to date, have involved ceramics or spherical metal powders. Since the use of irregular metal powders represents a promising way to reduce overall production costs, this study aims to investigate the potential of manufacturing powder injection molded parts from irregular commercial iron powders using the LPIM approach. To this end, a low viscosity feedstock was injected into a rectangular mold cavity, thermally wick-debound using three different pre-sintering temperatures, and finally sintered using an identical sintering cycle. During debinding, an increase in pre-sintering temperature from 600 to 850 °C decreased the number of fine particles. This decreased the sintered density from 6.2 to 5.1 g/cm³, increased the average pore size from 9 to 14 μm, and decreased pore circularity from 67 to 59%.

The impact of binders and temperature on the rheological properties of feedstocks used in low-pressure powder injection molding was investigated. Experiments were conducted on different feedstock formulations obtained by mixing Inconel 718 powder with wax-based binder systems. The shear rate sensitivity index and the activation energy were used to study the degree of dependence of shear rate and temperature on the viscosity of the feedstocks. The injection performance of feedstocks was then evaluated using an analytical moldability model. The results indicated that the viscosity profiles of feedstocks depend significantly on the binder constituents, and the secondary binder constituents play an important role in the rheological behavior (pseudoplastic or near-Newtonian) exhibited by the feedstock formulations. Viscosity values as low as 0.06 to 2.9 Pa·s were measured at high shear rates and high temperatures. The results indicate that a feedstock containing a surfactant agent exhibits the best moldability characteristics.