Annular laser beam based direct metal deposition

The paper provides a description of a direct annular laser beam based metal deposition head, which makes use of axial material feeding and variation of the laser beam intensity distribution (LBID) on the surface of the workpiece. The application and advantages of the developed head are presented by processes of direct metal droplet, metal wire and powder deposition. Due to the achieved process symmetry, the stability and robustness of the processes are increased. This is the most clearly seen in the case of metal droplet deposition, which is an inherently unstable process. In the case of wire deposition, a precise pre-set of the proportion of energy input into the workpiece surface is enabled, which has been shown to be an important parameter affecting the stability and process outcome. In the case of laser powder deposition, the benefits of the developed head are reflected in achieved powder catchment efficiency greater than 80 % and in the head's ability to influence the deposited layer properties by adjusting the LBID. (C) 2018 The Authors. Published by Elsevier Ltd.