Abstract
The suitable powder flowability is critical to the success of powder spreading processes in powder-bed additive manufacturing (AM). There are several methods to test powder flowability, but the powder flowing is more complex in spreading processes and cannot be fully characterized with any single test method. Twelve kinds of powders which are widely used in AM are considered, and their flowabilities are measured. Besides the size and shape features of powders are described, the compressibility, shear and dynamic flow energy indexes of powders are measured by a FT4 powder rheometer. A comprehensive evaluation index (CEI) for evaluating powder flowability is proposed based on the principal component analysis of the test results, and reveals the impacts of powder surface modification and gradation on powder flowability. The CEI has a stronger correlation with the avalanche angle during powder spreading processes than other indexes, which is suitable to evaluate powder flowability in AM.
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•A comprehensive evaluation index is proposed by the PCA of powder rheology results.•The powder flowability is ranked by the comprehensive evaluation index.•Surface modification of powder can improve their flowabilities.•The powder gradation impacts their flowabilities.