Effect of build orientation on cross-sectional areas of sliced layers and geometrical accuracy in selective laser melting

Abstract

Additive manufacturing is a manufacturing process that allows the production of complex parts and has many advantages over conventional production methods. However, the pre-processing stage is still time-consuming and open to failure. Build orientation is one of the pre-processing stages, which have a crucial effect on support requirement, build cost, and accuracy of the produced part. In recent years, a number of research have been made to optimize build orientation for surface roughness, the requirement of support structures, build time, and cost. For metallic additive manufacturing, a limited number of research has been carried out. Selective laser melting is one of the powder bed fusion technologies that allows the production of high-performance metallic parts. In the selective laser melting process, some defects may occur due to residual stresses resulting from solidification during the process. Build orientation is important in selective laser melting to ensure proper heat flow throughout to entire structure during the process. After the build orientation is selected, the part slices into layers. Each layer builds on the previous layer, and production carries out. The cross-sectional areas of these sliced layers depend on the build orientation. This study investigates the effect of cross-sectional areas on the geometric accuracy of the part. The numerical evaluation shows that the distribution of layers has a significant impact on geometrical accuracy. First, the effect of the mean cross-sectional area on the thermal distortion was investigated. It is observed that the geometric accuracy of the part decreases for the build orientation, which has a higher mean cross-sectional area. In addition, it is revealed that the increase and sudden change of the cross-sectional area in the build direction negatively affect the geometric accuracy.