COMPACTION AND EJECTION OF GREEN POWDER COMPACTS

An experimental investigation into the compaction, relaxation, and eje ction of bush type components of different length made from iron, bron ze, ceramic, and carbon powder types is presented. The compaction phas e confirms the effect of friction between the powder and tooling and t he presence of consequent density gradients in the compact. The force relaxation between the compaction and ejection phases is shown to be n on-elastic for the ceramic powder and only approximately elastic for t he other powder types. For the final stage of ejection, the form of th e curves is dependent on the compact length, after the initial movemen t the force decreases in the shorter compact while there is an increas e for the longer component. In all cases there is a decrease just befo re the compact emerges from the die and a linear reduction to a zero v alue at the end of the ejection process.