Powder flowability characterisation methodology for powder-bed-based metal additive manufacturing

TLDR

In powder‑bed additive manufacturing, suitable powder materials and sufficient flowability are critical for producing high‑quality parts, as many process parameters influence build quality. This study develops quantitative parameters to qualify metal powders for selective laser melting based on their flowability. Flowability is quantified by statistically analysing avalanche angles and surface fractal dimensions, yielding a method that correlates with practical SLM performance. Analysis of 21 Fe‑ and Ni‑based powders revealed strong correlations between avalanche angles, surface fractal, particle shape, and measured flowability.

Abstract

Key in powder-bed-based additive manufacturing is the use of appropriate powder materials that fit to the process conditions. There are many parameters affecting the build process and the corresponding quality of the parts being built. Therefore, an accurate assessment of the powders becomes important. Such an assessment involves, besides others, the powder flowability, which should be sufficient in order to create good-quality powder layers. The current study aims at the development of suitable parameters and values for the qualification of metal powders for selective laser melting (SLM) with regard to their flowability. The powder flowability is assessed by the statistical analysis of the measured powder avalanche angles and the powder surface fractal, which give valuable information about the significance of inter-particle forces. A set of 21 different Fe- and Ni-based powders has been analysed and good correlations between the powder avalanche angles, the surface fractal and the particle shape with the optically evaluated flowability could be derived. The method allows a quantitative powder flowability assessment, which correlates with the experiences for powders for powder-bed-based additive manufacturing, especially for SLM.