Side surface topography generation during laser powder bed fusion of AlSi10Mg

Abstract

Additive manufacturing (AM) is a direct manufacturing process that makes it possible to fabricate “near net shape” freeform parts. Among the many metal AM techniques, laser powder bed fusion (LPBF) is the most effective at obtaining complex structures with internal cavities, such as tortuous heat exchangers or lightweight lattice structures. AM technologies have therefore attracted considerable attention, which has led to research and development in many industries. Nevertheless, the surface topographies obtained by current AM techniques are still limiting industrial implementation for parts with high requirements. In this work, surface generation during LPBF was studied and optimized. The main aims were i) to optimize both side surface roughness and material density by studying the influence of the primary process parameters and ii) to investigate the effect of process options on side surface roughness generation for optimization purposes. The roughness dispersion and process reproducibility were also monitored and evaluated. A relationship between top and side surface roughness and material density was established. As a result, both optimizations could be performed in parallel. Analysis of the process reproducibility revealed an important roughness dispersion, especially from one side to the other. Consequently, recommendations on surface measurements were proposed. Compensations and contour settings are key parameters that can help reduce the side surface roughness. Indeed, geometrical positioning of the different weld tracks is also an important issue that must be addressed to reduce surface roughness. Based on the findings of this study, it is possible to reduce the areal average roughness Sa from 40 to 10 µm.