Simulation analysis of flow field optimization for powder bed surface integrity and spatter particle removal

Abstract

Spatter particles are a major cause of part defects during laser powder bed fusion (LPBF). Filling the working chamber with an inert gas prevents oxidation of the part and simultaneously removes spatter particles. The flow of inert gas in the working chamber influences the spatter-particle trajectory. This study develops a new wind-duct circulation system design based on inert-gas flow characteristics. The inert gas flow characteristics in the chamber were investigated using a coupled computational fluid dynamics and discrete phase model. The Coanda effect influence on the wind field uniformity and motion trajectories of spatter particles in different regions of the LPBF chamber was analyzed. A Bernoulli-effect three-wind duct structure was designed to attenuate the Coanda effect, and the effects of nine sets of wind speed combinations were investigated. The results demonstrate that the newly designed three-wind duct structure effectively reduces the Coanda effect of the flow field inside the working chamber. Wind speed requirements in each functional area are ensured and the removal efficiency of spatter particles is enhanced (79–96 %). This solution addresses a critical issue found in existing commercial LPBF equipment, providing a reliable reference for the subsequent optimization and design of duct circulation systems.