Effect of processing parameters on overhanging surface roughness during laser powder bed fusion of AlSi10Mg

Abstract

Abstract It is often required to add a support structure for overhanging surface in additive manufacturing (AM), especially during laser powder bed fusion (LPBF), which has a considerable impact on the promotion and wide application of this technique. The aim of this study is to evaluate the influence of process parameters on the overhanging surface roughness of AlSi10Mg specimens without a support structure under different build angles, 30°, 45° and 60°, respectively. A design of experiment (DoE) approach was adopted to clarify the correlations between the overhanging surface roughness and the causative the process parameters such as contour laser power, contour scanning speed, infill laser power, infill scanning speed and infill scanning angle. The results showed that the influence of each process parameter on the overhanging surface roughness varies with the change in build angle. Above all, the dominant factor was the contour scanning speed. The results of the comparison show that the contour process parameters are much more influential than the infill process parameters. In addition, the process parameters affected the overhanging surface roughness were on the decrease as the build angle increases. When the build angle was 30°, it was necessary to comprehensively consider the influence of infill scanning angle, contour scanning speed and infill scanning speed to obtain a smooth overhanging surface with a low roughness. However, as the build angle increased to 60°, only the contour scanning speed had a highly significant impact. The results also revealed that apart from the contour scanning speed, the interaction between contour scanning speed and contour laser power should be given priority when the build angle is 30° or less. The lowest roughnesses of overhanging surface with build angles of 30°, 45° and 60° were 10.9 μm, 7.9 μm and 4.22 μm, respectively.