Study on SLM fabrication of precision metal parts with overhanging structures

Precision metal parts for directly fabricating are often with overhanging structures. The two forming defects, warping and sinking will damage the overhanging structure, so how to ensure its fabrication is one of the key issues of Selective Laser Melting. In this study, by using self-developed SLM equipment and 500 mesh spherical 316L stainless steel powder, from the perspective of laser energy input, the overhanging structure fabricating characteristics of selective laser melting were experimented and summarized. Based on the fabricating limitation and controlling process, for several different types of parts, the pre-optimization methods of directly rapid fabricating technology for precision metal parts with overhanging structure were summarized: improving the overhanging structure or modifying the part's placement orientation according to the actual fabricating conditions, so that to avoid overhanging structures cannot be built; designing supports under the fabricating process limitation to ensure the overhanging structure's fabrication. Based on the process limits, this study discussed the overhanging structure optimization methods from the perspective of the SLM model preprocessing and obtained a good application effect.