Effect of Process Parameters on the Surface Roughness of Overhanging Structures in Laser Powder Bed Fusion Additive Manufacturing

The development of additive manufacturing has allowed for increased flexibility and complexity of designs over formative and subtractive manufacturing. However, a limiting factor of additive manufacturing is the as-built surface quality as well as the difficulty in maintaining an acceptable surface roughness in overhanging structures. In order to optimize surface roughness in these structures, samples covering a range of overhang angles and process parameters were built in a laser powder bed fusion system. Analysis of the surface roughness was then performed to determine a relationship between process parameters, angle of the overhanging surface, and surface roughness. It was found that the analysis of surface roughness metrics, such as Rpc, Rsm, and Rc, can indicate a shift between surfaces dominated by partially melted powder particles and surfaces dominated by material from the re-solidified melt track.