Powder spreading defects and their impact to porosity and form deviations

Laser powder bed fusion (PBF-LB) provides an opportunity for high mix low volume parts at the expense of needing fine-tuned process parameters. The interaction between the powder bed quality and the lasing process has been understudied in literature. Spatter, superelevation, recoater selection, and wear on the recoater blade can all influence the spread profile. These defects can subsequently impact the porosity and geometric accuracy of the part. In the present work, the significance of the size of the wear on previously used recoater blades was investigated for its impact on the part’s geometric accuracy and resultant porosity profile. Laser line profilometry was employed to measure the topography deviations in the powder bed caused by spreading with a worn recoater. Lightly damaged recoater induced topography deviations were not seen to cause significant surface swelling on the part, whereas instances of heavier recoater damage were. The influence of recoater damage on the porosity profile was difficult to assess given the process parameters. The results of this study seek to inform the operator of the size criticality of recoater damage and its resultant impact on part and build quality.