An extrusion based additive manufacturing (EAM) technique, recently became competitive for the rapid production of metals and ceramics components. This is made possible by extruding the metal or ceramic material in solid powder form, mixed with a binder, i.e. an expendable viscous fluid, which is removed from the part after 3D printing. The strength of these technologies relies on the large design freedom allowed by and by the cost efficiency advantage vs. alternative metal additive manufacturing processes based on high energy beams, e.g. laser/electron beam.EAM of metals and ceramics is not yet widespread, and the published scientific and technical literature is rapidly growing, but still less extensive than the literature on FDM of plastics or SLM of metals. This paper aims at filling this gap. Fused Deposition Modeling (FDM) and Powder Injection Molding (PIM) are identified as preceding or enabling technologies for EAM. This paper systematically reviews all the aspects of feedstock extrusion-based AM processes used for production of complex shaped parts. Then, the unique characteristics and advantages of the process are discussed, with respect to materials and process steps. The key process parameters are explained to illustrate the suitability of the process for diverse domains of applications.

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Extrusion-based additive manufacturing (EAM) is a relatively new process developed for the production of complex metallic and ceramic parts needed in smaller quantities. The debinding and sintering step of EAM is adopted from a well-known powder injection molding process. However, the 3D printing step needs special consideration to make EAM competent in the era of rapid manufacturing. This study is intended to investigate the effect of common printing parameters on the microstructure and mechanical properties of sintered stainless steel 316L (SS316L) parts manufactured through the EAM process. Part orientation (Ori), extrusion velocity (Ve), and layer height (h) were changed in experimental runs by following a full factorial design. Extrusion pressure as an indicator of melt stability and a grey relational grade as a combined response of sintered properties were analyzed against varying printing parameters. Physical characteristics measured during debinding and sintering shows near isotopic shrinkage and the process is stable.Metallographic characterization in terms of porosity and grain size indicated minor differences when Ve and h were altered. Sintered parts showed improved properties when printed with vertical part orientation and h = 0.5 mm. Whereas Ve which contributes significantly to the build-up rate was found to be responsible for melt stability. Ve at 12.5 mm/s exhibited melt stability and higher sintered properties.

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