Multi-physical analysis of thermo-optical effects for different Selective Laser Melting (SLM) scanning strategies

In this paper, transient thermo-optical effects in protective windows for selective laser melting are analyzed by means of a multi-physical analysis. The temperature distribution of the window is simulated for different scanning strategies and orders of exposure. Therefore, cubic test specimens are virtually built and the resulting axial and lateral focus shift is analyzed. Furthermore, the impact of the distance between the laser scanner and the protective window is analyzed. The simulations predict that spreading the thermal load on the window both spatially and temporally reduces the focus shift. Consequently, the focus shift is reduced if the window is placed further away from the laser scanner.