Characterisation of powders in low pressure region of yield surface

Abstract

Cold die powder compaction can be a challenging manufacturing route for complex components. Setting the filling and pressing tools is a difficult and time consuming operation. Numerical methods can assist process engineers; however, the result can only reflect the reality if the material characteristics are well established mathematically for the simulation systems. The aim of the present work is to review two tests, which are easy to set up, and review them with the aim of establishing whether or not they produce useful and accurate data to establish a mathematical description of the material behaviour. The work draws attention to the limitations within which data from the simple compression test and the Brazilian disc test can be used to establish the behaviour of powders under shear dominated stress and strain conditions. The study is conducted on a ferrous and an alumina powder to highlight differences in behaviour. The present work is followed by a complementary article showing the exploitation of the data collected here to establish a valid mathematical model of the materials’ consolidation behaviour.