Modeling of Powder Spreading in Laser Powder Bed Fusion and Roller Rotational Strategies

Abstract

Powder spreading is critical in Laser Powder Bed Fusion (PBF-LP), directly influencing the powder bed's uniformity, packing density, and overall quality. This work focuses on optimizing spreading speed, roller configurations, and rotational speed strategies through Discrete Element Method (DEM) simulations to enhance the performance of additive manufacturing processes. The research is structured around three key objectives. First, the influence of varying spreading speeds on powder bed characteristics is analyzed. Results indicate that increasing spreading speed reduces packing density and layer thickness for non-rotating, counter-rotating, and sub-rolling configurations due to powder dragging. In contrast, the super-rolling configuration effectively balances momentum transfer, enhancing packing density and layer thickness while maintaining uniformity, albeit with a slight increase in surface roughness. Second, the study evaluates the impact of circumferential speed on powder spreading. It reveals that forward-rotating rollers significantly improve packing density, layer thickness, and mass fraction as rotational speed increases, while counter-rotating rollers show a decline in these metrics. Despite improving productivity, larger roller sizes lead to greater powder bursts, non-uniformity, and surface roughness, highlighting the need for optimized operational parameters. Lastly, adaptive rotational speed strategies (Profiles A–F) are introduced to address challenges in high-speed spreading. Profile F stands out as the optimal configuration, achieving maximum packing density, minimal variation coefficients, and superior mass fraction. Its high initial clockwise rotational speed, gradually reduced to zero, ensures uniform powder deposition, minimal surface roughness, and stability under high spreading speeds. This work offers a comprehensive framework for optimizing PBF-LP powder spreading processes, emphasizing the interplay between spreading speed, roller size, and rotational strategies. These findings provide valuable insights for enhancing efficiency, reliability, and quality in roller-spreading in additive manufacturing.