Abstract
Powder-bed fusion (PBF) processes refer to a subset of Additive Manufacturing (AM) techniques where powder is spread on the build-plate before melting (by a laser or electron beam). While PBF processes are attractive due to their ability for realizing complex structures that are either difficult or impossible to create through conventional means, the parts fabricated with these techniques can exhibit defects such as pores, inclusions, and excessive surface roughness. To minimize these defects, much research has been dedicated towards process maturation by optimizing laser or electron beam parameters. However, these developmental efforts typically do not address the recoating process where achieving dense and uniform layers of powder is a necessity for ensuring process repeatability and part quality. While the recoating process can be studied through experimentation, the dynamics of particle movement are difficult to analyze experimentally. Therefore, in this study, powder spreading in PBF was simulated through the Discrete Element Method (DEM) to elucidate the mechanisms that control powder-bed quality. Utilizing the Buckingham Pi theorem, a dimensionless metric referred to as the spreading index is developed that combines powder-bed density, roughness, and particle size to assess the quality of powder layers. The formulated spreading index is then related to several dimensionless quantities that provide insight into the mechanisms dominating powder spreading in PBF. The DEM simulations conducted in this work focused on the scenario where powder is spread onto an existing powder bed and revealed that a reduction in the recoating velocity causes an increase in the spreading index while little to no impact on the spreading index was observed when varying layer thickness from 30 µm to 75 µm. Particle size effects on the powder-bed quality were also investigated.
Recommended Citation
A. T. Sutton et al., "Modeling Powder Spreadability in Powder-Based Processes using the Discrete Element Method," Additive Manufacturing, vol. 92, article no. 104345, Elsevier, Jul 2024.
The definitive version is available at https://doi.org/10.1016/j.addma.2024.104345
Department(s)
Mechanical and Aerospace Engineering
Second Department
Materials Science and Engineering
Keywords and Phrases
Additive manufacturing; Discrete element method; Powder spreading process; Powder-bed fusion; Spreadability
International Standard Serial Number (ISSN)
2214-8604
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2024 Elsevier, All rights reserved.
Publication Date
25 Jul 2024
