Similar to direct energy deposition (DED) technology, electrostatic adhesion method can also be employed to deposit powder on targeted areas without direct contact. In this paper, feasibility of utilizing the electrostatic adhesion method (EAM) in material deposition step of metal-power-based additive manufacturing is assessed through theoretical models and experimental verifications. A dielectric layer is proposed to be pre-coated on targeted areas to keep the powders being electrostatically attracted and charged without dropping before laser scanning process. Through this study, it is found that the net force of a single metallic particle on top of the deposited powder layer with a different thickness of the dielectric layer can be determined, leading to the suggestion of suitable coating thickness corresponding with desired particle radius. Results showed that the deposition layer thickness can be predicted with the knowing coated dielectric layer thickness and the powder size distribution. With the proposed electrostatic deposition method, a thinner layer compared to DED technology can be deposited, while maintaining its ability to deposit powder layer over a larger area. Through experiments, the developed electrostatic model is validated with results indicating that the deposition layer thickness can be predicted and controlled with the knowing coated dielectric layer thickness and the powder size distribution.
Effect of 316L stainless steel powder size distribution on selective laser melting process
