PSI - Issue 42

Saveria Spiller et al. / Procedia Structural Integrity 42 (2022) 1239–1248 Saveria Spiller/ Structural Integrity Procedia 00 (2019) 000 – 000

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FDM: Fused Deposition Modeling MEX: Material Extrusion PBF: Powder Bed Fusion BJ: Binder Jetting MIM: Metal Injection Molding DIC: Digital Image Correlation 1. Introduction

The term Material Extrusion Additive Manufacturing (MEAM) refers to the multiphase technique depicted in Fig. 1. In the literature different terms are used to indicate the process, such as MEX-Material Extrusion (Cerejo et al., 2021; Sadaf et al., 2021) or SDS-Shaping, Debinding, and Sintering (Gonzalez-Gutierrez et al., 2018; Thompson et al., 2019). The present work is focused on the production of metallic parts, but both metal and ceramic components can be obtained through MEAM. When dealing with metals, the technique is also referred to as Metal-FFF (Alkindi et al., 2021; Caminero et al., 2021).

GREEN PART

BROWN PART

Fig. 1. a schematic of the process of Material Extrusion Additive Manufacturing

As mentioned previously, the main phases of the technique are called shaping, debinding, and sintering. During the first phase, the components are fabricated using a regular FDM printer and a special material called highly-filled polymer: this polymer is loaded with a high percentage of metal (or ceramic) powder. The outcome is called green part and it has no significant mechanical integrity due to the non-homogeneous composition (Godec et al., 2020). The polymeric share in the green part is removed during the second phase, the debinding. The resulting component, referred to as brown part, consists of packed metal powder and it is extremely fragile. Finally, the sintering process allows the powder particles to bond together and densify the final part. To the best of the authors’ knowledge, the technique was first used in the late 90s. Some of the first works available in the literature are Agarwala et al. (1996), Wu et al. (2002), and Wu et al. (1999). Recently, MEAM has been investigated, especially with highly-filled polymers added with stainless steel powder (Godec et al, 2020; Hassan et al, 2021; Kurose et al, 2020; Damon et al. 2019; Alkindi et al. 2021; Suwanpreecha et al. 2021; Henry et al. 2021; Galati et al, 2019; Rosnitschek et al, 2021; Tosto et al, 2021). Other metals were successfully used, such as Titanium (Shaikh et al., 2021; Singh et al., 2020, 2021; Thompson et al., 2021), Copper (Dehdari Ebrahimi et al., 2018), Tungsten, and other hard metals (Abel et al., 2019; Bose et al., 2018; Lengauer et al., 2019).