Raking and Fusing Behaviors during Fabrication of Multiple-layers in Powder Bed Fusion: an Integrated Discrete Element and Computational Thermal Fluid Dynamics Study

In the powder bed fusion (PBF) type additive manufacturing (AM), understanding the relationship between the quality of the powder bed and the powder spreading process is crucial to avoiding defect formation. In this study, we investigated the powder-raking behavior during the multiple-layer fabrication process by discrete element method (DEM) and computational thermal-fluid dynamics (CtFD) simulations. The integrated PBF process simulation revealed that the gap height between the powder spreading blade and the build platform increases nonlinearly with the number of stacking layers, and accordingly, the powder-covered area ratio increases in the formed powder beds and affects the melt pool shapes. The powder raking behavior and melting and solidification behavior are related to each other, and both the powder raking and the irradiation conditions need to be optimized to obtain a high-quality part in the PBF process.