Experimental and numerical investigation of re-coating process parameters on the spreadability of plasma-atomized powder

Abstract

In powder bed fusion additive manufacturing (PBF-AM), the ability to form dense, uniform thin layers “Spreadability” is a primary determinant of build quality yet remains without a standardized assessment. This study integrates controlled re-coating experiments with discrete element method (DEM) simulations to evaluate the spreadability of plasma-atomized AlSi10Mg powders and to propose quantitative, transferable screening metrics. Five powders with distinct particle size distributions were tested across layer thicknesses from 25 to 100 μm, recoating speeds from 50 to 200 mm/s, and multiple blade geometries. The measured powder layer density (PLD) spanned 44 to 65 %; thicker layers and moderate speeds increased PLD, and a round blade consistently outperformed flat, inclined, and sharp profiles. Material determinants of spreadability were quantified. Linear correlations were observed between PLD and static packing indices apparent, tapped, and conditioned bulk densities with coefficients of determination in the range 0.80 to 0.95, indicating that powders capable of dense static packing also compact effectively under the re-coater. Cohesion measurements identified an operational window centered near 0.30 to 0.35 kPa; PLD declined at higher cohesion due to agglomeration. Segregation mapping across start, middle, and end regions using D10, D50, and D90 showed size-dependent migration that was modest for narrow and medium distributions and more pronounced for wide and coarse distributions. Elevated relative humidity increased effective cohesion and reduced PLD for fine and medium powders, while wide and coarse powders were comparatively insensitive. DEM resolved three coupled sub-mechanisms; detachment, redistribution, and settling; that rationalize these trends. Based on the combined evidence, preliminary spreadability guidelines are proposed: relative tapped density of approximately 67 % or higher, conditioned bulk density of approximately 62 % or higher, cohesion in the range 0.30 to 0.35 kPa, and particle size distribution span between 0.8 and 1.0. These results provide a framework for assessing and standardizing powder spreadability in PBF-AM.