Spatter-flow interaction behavior under protective gas flow parameters and scanning directions

Abstract

Spattering is a common issue in selective laser melting (PBF-LB), causing contamination of the powder bed and negatively affecting product quality. One solution to this problem is introducing an inert gas flow that can remove spatter particles. The gas flow's characteristics and interaction with spatter particles depend on process parameters and involve a multi-physical field coupling process. However, current research mainly focuses on spattering behavior under single process conditions and lacks systematic exploration of gas flow characteristics and their interaction with spattering. This paper investigates the gas flow-spatter interaction process in PBF-LB, constructing a coupled model of Computational Fluid Dynamics (CFD) and Discrete Element Method (DEM). The model investigates the effects of inlet height, inlet flow velocity and laser scanning direction on the deposition and removal of spattered particles. The study reveals that flow velocity and inlet height affect the dynamic behavior of spattering by altering the flow distribution, while the laser scanning direction influences spatter dynamics by changing the direction of spatter ejects. The rate of spatter removal increases as the angle between the scanning direction and flow direction, and the flow velocity, increase. Conversely, it decreases as the inlet height increases. This work provides theoretical understanding of the interaction between gas flow characteristics and spattering, which is significant for optimizing printing process parameters and improving printing quality.