High-gravity effect on melt pool dynamics in laser powder bed fusion of fine powders

While the application of fine powders in additive manufacturing offers significant potential for high-resolution fabrication, their use remains constrained by poor flowability and inconsistent spreadability. The efficacy of artificial gravity as a mechanism to mitigate these challenges remains largely unexplored. This work simulates the dynamics of the melt pool within a compacted fine powder under high gravity, using the validated volume-of-fluid (VOF) approach. The results demonstrated that, during the melting process, the packing fraction of the fine powder bed exerted a significantly greater influence on the melt pool dimensions than the applied high gravity. However, under the applied acceleration range from 1 G to 20 G, high gravity strongly influenced melt-pool flow behavior, solidification, and surface uniformity. Under these simulation conditions, the melt flow changed from a mainly horizontal trajectory to a downward-directed flow, promoting penetration into the compacted powder bed. The evaluation of surface uniformity indicates that the melt pool top surface became more uniform, with reduced waviness, potentially decreasing the surface roughness of the fabricated material. Furthermore, the melting behavior under high gravity was examined for fine and coarse powder beds, both maintained at a packing fraction of 0.5. Observations indicated that the coarse powder bed produced an irregular melt pool topography, whereas the fine powder bed maintained a smooth and uniform surface. This underscores the potential for fine powders to minimize structural defects, ultimately producing reliable fabricated components with potential for improved microstructural homogeneity.