Flowability of steel and tool steel powders: A comparison between testing methods
Lorenzo Marchetti, Christopher Hulme-Smith
Abstract
The flow behaviour of a powder is critical to its performance in many industrial applications and manufacturing processes. Operations such as powder transfer, die filling and powder spreading all rely on powder flowability. Multiple testing methods can help in assessing flowability, but it is not always clear which may better represent specific flow conditions or how different metrics correlate. This study compares 8 different flowability testing methods using 11 steel powders varying in chemistries and size fractions. Regression analysis was used to test the relationship between each flowability metric obtained. Some metrics, such as the conditioned bulk density, relate to many flowability indicators. Others, such as the basic flowability energy, show poor correlations to other variables, likely describing different aspects of the powder flow behaviour. When two metrics show a strong correlation, as between conditioned bulk density and Hausner ratio, a numerical relationship is derived: CBD = − (5.65 ± 0.86)HR g cm−3.