Laser-aided directed energy deposition of metal powder along edges

Abstract Laser-aided directed energy deposition of metal is a process in which a volume is built up layer by layer and each layer is completed with a tool path along the layer boundary. This so-called contour line is of central importance in terms of the extent to which a near-net-shape geometry is realized. These contour lines form the surface of the component. In order to get a deeper understanding of the influence of the process parameters or the process strategy on the formation of the track geometry, we have developed a simulation tool. With this tool it is possible to determine the track geometry as a function of the process parameters in advance and to develop computer-aided process development. The formation of the melt bath surface is essentially controlled by the capillary forces. For a numerically accurate calculation of the capillary melt bath surface, the calculation was performed by minimizing an area energy functional and considering the time-dependent melt volume as a constraint with a Lagrange parameter. This approach explicitly considers the relevant shaping forces for the melt pool surface, i.e. the product of surface tension and mean curvature. This is new compared to other approaches in the literature which are based on the Level Set method and describe the time evolution of the melt pool surface via a flow-based evolution equation. The paper explains and presents the physical model and its numerical implementation as well as first results.