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%.

Low-pressure powder injection moulding (LPIM) is a cost-effective manufacturing technology used to fabricate complex-shaped parts with high mechanical properties at low-or highvolume production. This research work presents an experimental approach to investigate the debound/sintered properties of iron components produced by the LPIM process using iron-based powders exhibiting different particle shapes and size distributions. Four lowviscosity feedstocks were mixed and injected into a rectangular mould cavity before being thermally wick-debound and finally sintered using identical debinding and sintering cycles. This study confirms that both irregular and spherical iron powders can be shaped via the LPIM process. The solid loadings obtained with these two powder morphologies, varying from 58 to 62 vol.-%, represent expected values. The trend in the density values obtained with irregular (∼6.6 g/cm 3 ) and spherical (∼7.5 g/cm 3 ) powders was validated by metallographic observations.

This work presents an experimental approach employed to evaluate the influence of binder constituents and solids loading on the rheological behavior and molding properties of irregular shape iron-based feedstocks used in low-pressure powder injection molding. Thirty-six (36) different feedstocks formulated from one new in-development iron-based powder and different wax-based binder systems (paraffin wax with surfactant and thickening agents) were obtained for solids loading varying from 50 to 68 vol. %. The viscosity profiles were experimentally measured at different temperatures using a rotational rheometer in order to quantify the threshold proportions of each ingredient in the binder systems, identify the best feedstock candidates, and calculate their moldability indices, which were finally validated using real-scale injections. Results confirmed that the best feedstock formulation was the one containing paraffin wax with 1 vol. % stearic acid used as a surfactant, 2 vol. % ethylene-vinyl acetate used as a thickening agent, and 2 vol. % carnauba wax used as a shrinking agent. An irregular shape iron-based feedstock with maximum solids loading of 58 vol. % was successfully injected.

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