Correlation of Spatter Quantity and Speed to Process Conditions in Laser Powder Bed Fusion of Metals

Abstract

The results of spatter measurements within laser-based powder bed fusion of metals are presented. A stereoscopic imaging setup and corresponding reconstruction algorithm are used to determine three-dimensional measures of the spatter characteristics from experiments with 1.4404 stainless steel. The spatter characteristics are correlated to the process zone morphology and evaporation behavior. The evolution of the spatter count over consecutive tracks is investigated and shows a decrease and convergence towards a constant value. Experiments with the process gases argon, helium and nitrogen reveal that the spatter count decreases with the gas density, whereas the spatter speed stays unaffected. This confirms the key role of the process gas in the entrainment of powder particles and the associated spatter generation. The results indicate that macroscopic spatter characteristics contain relevant information about microscopic process behavior. This makes spatter characteristics a designated process feature for new sensing approaches for the observation of industrial applications.