Experimental Approach for Development of a Powder Spreading Metric in Additive Manufacturing

Abstract

The powder spreading is a vital step of powder-based Additive Manufacturing (AM) processes. The quality of spread powder can considerably influence the properties of fabricated parts. Poorly-packed powder beds with high surface roughness result in printed part layers with large porosity and low dimensional accuracy, leading to poor mechanical properties. Therefore, the powder spreadability and its dependence on process parameters and powder characteristics should be quantified to improve the efficiency of powder-based AM methods. This study proposes a novel dimensionless powder spreadability metric that can be commonly used in different powder-based AM processes. The quality of spread powder in terms of powder bed density and surface roughness was evaluated by adjusting the process parameters, including recoating velocity and layer thickness, and powder characteristics, including particle size distribution. In addition, the dynamic repose angle was proposed and examined as another powder spreadability metric. The results showed that these two proposed metrics were strongly correlated, and lower recoating velocity and larger layer thickness led to higher spreadability and lower dynamic repose angle.