Discrete Element Simulation of the Effect of Roller-Spreading Parameters on Powder-Bed Density in Additive Manufacturing.

The powder-bed with uniform and high density that determined by the spreading process parameters is the key factor for fabricating high performance parts in Additive Manufacturing (AM) process. In this work, Discrete Element Method (DEM) was deployed in order to simulate Al2O3 ceramic powder roller-spreading. The effects of roller-spreading parameters include translational velocity V-s, roller's rotational speed omega, roller's diameter D, and powder layer thickness H on powder-bed density were analyzed. The results show that the increased translational velocity of roller leads to poor powder-bed density. However, the larger roller's diameter will improve powder-bed density. Moreover, the roller's rotational speed has little effect on powder-bed density. Layer thickness is the most significant influencing factor on powder-bed density. When layer thickness is 50 mu m, most of particles are pushed out of the build platform forming a lot of voids. However, when the layer thickness is greater than 150 mu m, the powder-bed becomes more uniform and denser. This work can provide a reliable basis for roller-spreading parameters optimization.