Feedback control of selective laser melting

Selective Laser Melting (SLM) is a powder bed based Rapid Manufacturing (RM) process in which parts are built by selective melting of layers of powders by means of a laser source. The main advantage of this technique is the possibility of making very complex and custom made pieces in a rather fast way. In this paper a feedback control system for Selective Laser Melting is presented. A feedback control system with a high-speed CMOS camera and a photodiode has been installed on the SLM-machine developed at K.U.Leuven-PMA. Both sensors were used independently to keep the melt pool area constant, especially in the case of scanning overhanging structures in which the melt pool would become very large. First motivation for the feedback system and the outline of the feedback system will be described. Next case studies are presented, in which both the photodiode as the CMOS camera have been used to control the SLM process. Clearly, the feedback control system can improve the surface quality of the lower surface of the overhang. Figure 1: (left) top view of bad part contour at sharp corner (right) side view of dross formation at down facing surfaces Bad sharp corner Dross formation Y