Machinability of 3D printed metallic materials fabricated by selective laser melting and electron beam melting: A review

In recent years, additive manufacturing (AM) of metallic parts opens new opportunities for many critical industrial sectors and individual necessities. The high quality and more functional components which are difficult or impossible to produce with the conventional methods can be readily manufactured using AM. In addition, minimization of design constraints, minimal material usage and elimination of tooling costs are some of the other notable advantages of this technology. However, poor surface quality of the produced parts is an inherent output of AM. Surface quality has an important effect on the functional performances of the machinery components. Therefore, additional machining operations are usually needed for the AM components to ensure desired part performance. In this context, it is critical to determine machinability and part quality of AM components since they can exhibit different mechanical, physical, and microstructural properties when compared to conventionally manufactured equivalents. In this review article, machinability of 3D printed metallic parts fabricated by Selective Laser Melting (SLM) and Electron Beam Melting (EBM) technologies was investigated. For that purpose, turning, milling, drilling, and micro machining performances of SLM and EBM parts were evaluated considering surface integrity, tool wear, tool life, cutting forces and chip formation depending on the different cutting conditions, 3D printing parameters, building directions, and post-process heat treatments. In addition, some mechanical and physical properties, and microstructural properties of metallic SLM and EBM parts were also introduced from a machinability point of view. The main objective of this paper is to compile relevant information about the conventional and micro machinability performances of 3D printed metallic materials fabricated by SLM and EBM into a single document and to give some suggestions about machining strategies of these novel engineering materials. In addition, the possible perspectives of future studies for enhancement of machinability and surface integrity of AM components are also introduced.