A review of powder deposition in additive manufacturing by powder bed fusion

One of the most important aspects of Powder Bed Fusion (PBF) processes is the powder layer spreading. The powder layer needs to be applied in such a way that its evenness and homogeneity is ensured. This, in turn, will ensure that no inconsistencies or defects of the non-sintered powder layers, internal or superficial, will be inherited to the finished part, which would negatively affect its mechanical properties and dimensional accuracy causing drastic quality deterioration. This paper aims to address the powder recoating process parameters, intrinsic and extrinsic, that affect the non-sintered powder layer quality and, ultimately, the finished part quality. The non-sintered layer's quality and the finished part's quality are examined via certain powder layer quality indicators (PLQIs) and finished part quality indicators (FPQIs) respectively. This work systematically identifies and records the connections between process parameters on one hand and PLQIs and FPQIs on the other hand. Moreover, the multiple ways and corresponding methods found in literature in which the powder layer quality can be quantified are presented with the advantages and disadvantages of each one. Finally, gaps in literature are revealed and suggestions for future work to focus on are made.