Metal Additive Manufacturing Conference - MAMC 2022

In recent years, there has been much activity to develop a test to measure the quality of thin layers produced from metal powders, otherwise known as the property of spreadability. Several strategies have been published but no single test has yet been adopted by the powder metallurgy community. This study presents the development and testing of one such measurement technique that is simple, fast and inexpensive. It incorporates both a mass-based measurement and image analysis for density of the layer and to identify defects within the layer. Furthermore, the measurement technique has been benchmarked for over twenty powders and compared to several tests for flowability, namely Hall and Carney flowmeter tests, static angle of repose, Hausner ratio and powder rheometry. The new measurement technique was shown to be repeatable and reproducible. It is able to identify defects using image analysis and automatically measure layer area. Multilinear regression analyses with all experimental techniques indicate that layer density measured using the new technique is correlated to a combination of flow rate index, specific flowability energy and Hausner ratio. However, these metrics must be used in combination and it is not possible to use any one of them to predict layer density. Other flowability metrics showed no correlation to spreadability. These results can be used to inform experimental design of powder testing to ensure adequate spreading behaviour in additive manufacturing and can also be used to aid development of a spreadability test.