Study of powder entrainment in L-PBF process with maximum hatching space for higher process efficiency

Abstract

Laser powder bed fusion (LPBF) is a well-known metal additive manufacturing method with high processing flexibility, but the processing time and energy cost are important issues. As the objectives of this study, the optimal hatching is established not only for the quality but also for the process efficiency. The powder entrainment (from CFD-DEM simulation) and the melt pool geometry (from heat transfer finite element simulation) are used to extract the optimal hatching space. In maximizing the hatching space to enhance the process in throughput, the high quality of the 3D part is still maintained. The experimental results showed an 80% increase in efficiency with the optimal 90μm hatching space compared to previous studies using AA6061 with 2 vol% YSZ (Yttria-stabilized zirconia) with the common 50μm hatching space (due to the laser beam size overlap in 50%) and the relative density of 99% is still achieved, thus demonstrating that the process efficiency was improved while maintaining high quality. Uniquely, it is found that the laser power and scanning speed mainly affect the relative density of a 3D object instead of the hatching space. Thus, the maximum process efficiency in throughput can be significantly achieved by designing the maximum hatching space. To the authors' knowledge, there are few studies on process optimization based on the powder phenomenon, thus an innovative study is proposed to extract the maximum hatching space based on powder motion and melt pool geometry.