Laser powder bed fusion recoater selection guide-Comparison of resulting powder bed properties and part quality

Spreading devices used to create powder layers in the laser powder bed fusion of metals (PBF-LB/M) were found to have a significant impact on the additive manufacturing process. However, previous research primarily focused on theoretical investigations, including recoater concepts that are not available on the market, while no comprehensive comparison of commercially available spreading devices currently exists. The aim of this study is therefore to examine the powder bed properties and part qualities that can be achieved with the three most common types of recoater: carbon fiber brushes, polymer lips, and high speed steel (HSS) blades. Identical build jobs were produced using each of the spreading devices. Their capabilities were assessed by nine evaluation criteria, including dimensional, metallurgical, and mechanical properties and criticality of particles abraded from the spreading devices. Based on these quantitative findings, a spreading device selection guide was compiled for the benefit of PBF-LB/M practitioners. All recoaters yielded processes with high stability and part properties that were on a par with or even outperformed the nominal values from the literature. However, the HSS blade was found to provide higher accuracy and stability in steady-state processes. In turn, the brush and lip are better suited for parameter development and design studies. Additionally, the lip was found to have economic benefits over the brush, while the brush was deemed an effective all-rounder.