Interfacial coefficients in powder metal compaction

A study has been made of the die compaction of metal powders and in particular the problems associated with friction between sliding surfaces have been examined. Friction which results from adhesion or welding, plays an important role in powder consolidation and is greatly influenced by the condition of the surfaces concerned. Attention has been focused upon the compact die interface and the interactions occurring within this region. In particular information has been obtained for friction coefficients between the sliding surfaces and the role of lubricants in affecting these parameters. An assessment has been made of the effect of admixed lubricant level upon the laboratory scale compaction of a reduced iron powder. Ejection forces have been measured and the effects of lubricant content and characteristics evaluated. Die material and surface finish has been shown to be of importance during compaction and ejection. Compact surfaces and strengths have been examined and correlated with the ejection stress data. [Continues.]