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 high-volume 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 low-viscosity 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/cm³) and spherical (∼7.5 g/cm³) powders was validated by metallographic observations.

Low-pressure powder injection moulding (LPIM) has advanced through developments in feedstock formulation, mould-filling simulation, thermal wick-debinding, and sintering of irregular metallic powders. This review focuses specifically on the wax-based, backbone-free branch of LPIM, in which thermal wick-debinding is the distinctive binder-removal route, as this is where the most recent quantitative progress has occurred. It synthesizes these developments and identifies the gaps that define the next phase of LPIM research. Wax-based binder formulations have been developed for stainless steels, iron, titanium, and Inconel 718, with solid loadings up to 62 vol.% and viscosities below 20 Pa·s. Numerical simulation has evolved from qualitative flow-pattern matching to quantitative in-cavity pressure validation, and current models reproduce experimental pressures with errors of 30%–64% across complex geometries. Thermal wick-debinding, the distinctive debinding route for backbone-free LPIM feedstocks, has been placed on a quantitative footing through a coupled experimental and COMSOL-based study. Sintering studies of irregular water-atomized iron powders, matched to optimized debinding and sintering schedules, have achieved densities and tensile properties comparable to those obtained with spherical gas-atomized feedstocks, supporting a lower-cost route to structural LPIM components. The review concludes with five research opportunities: closing the simulation–experiment gap; systematically studying the green-density–sintered-density relationship that distinguishes LPIM from HPIM, including dimensional accuracy and shrinkage anisotropy; extending to reactive and oxidation-sensitive alloys; integrating with material extrusion additive manufacturing, including SLA-printed and sacrificial mould strategies; and developing sustainable wax recovery, biosourced binders, and reduced-energy debinding routes.