Overview of debinding methods for parts manufactured using powder material extrusion

Material extrusion additive manufacturing (MEAM) is a common family of additive manufacturing processes based on the selective extrusion of a molten material in layers to build solid geometry. One of the emerging processes within this group is powder material extrusion (PME); in theory, it is based on the very common material extrusion (per ISO/ASTM 52900) process but uses modified hardware and design approaches to extrude feedstock consisting of metal or ceramic powder suspended within a thermoplastic matrix. The percentage of powder can vary from around 50% up to over 90%, making PME a feasible alternative to powder injection molding (PIM), some powder bed fusion (PBF) additive processes, and some powder metallurgy (PM) processes due to its very low cost, simple processing equipment, lack of industrial hazards, and lack of residual stresses. The produced parts are green, similar to what is obtained when using PIM, some PBF, and PM, and require debinding and sintering in order to be useful in practice. Much remains in development about how to properly use and design PME parts, including filament making, process steps, binder selection, debinding method, sintering approach, and characterization of the final parts. In order to contribute to more widespread adoption of the PME process for metals and ceramics, a comprehensive review of the literature on debinding processes relevant to PME was completed and is reported in this article. This review presents the state-of-the-art, discussed some useful and relevant approaches for the future from other manufacturing processes, and shines light on the needed work in this area for the advancement of PME as an end-user manufacturing process. This work, combined with knowledge of the sintering process, will provide a guide for future research and implementation of PME.