Impact of hatching strategies on overhang displacement in PBF-LB/M

Abstract One of the most widely used additive manufacturing processes for metals is the powder bed fusion process, using a laser beam to melt powder layer upon layer into complex three-dimensional structures. While this manufacturing technique offers considerable design versatility, it is limited by overhang features that necessitate support structures, with the required angles for these supports varying based on the material, process, and machine used. Overhang features are susceptible to distortion, which compromises process stability. If the overhang feature penetrates into the next layer of powder, the recoater that distributes the loosened powder can be damaged, which can lead to a total loss of the parts in severe cases. In this work, the effect of the laser path, the hatching, on the overhang displacement was investigated. Overhang specimens were built using different hatching strategies, orientations of the hatching sequence toward the gas flow, hatch lengths, and altered hatching in differently sized areas in the overhang. Among other implications, it was found, for the hatching, that the hatch length should be maximized to reduce overheating effects and displacement in overhang regions. The findings and their practical implications offer an overview of the overhang displacement and the influence of various hatching strategies and parameters. This research serves as a foundation for more advanced optimized hatching strategies that will reduce overhang displacement, increase process stability, and even further increase the freedom of design in additive manufacturing.