Effect of Lubricant Particle Size Distribution on the Processing and Properties of P/M Ferrous Parts

摘要

The role of lubricants during compaction is crucial and nowadays even more important, due to the increased number of PM parts with higher densities and/or challenging ejection conditions. The development of new lubricants for single compaction requires however an excellent understanding of the lubrication mechanisms and the behaviour of these new compounds. In this paper, the effect of the lubricant particle size distribution on the compaction and ejection behaviour, but also on the static and dynamic properties of ferrous powder metallurgy parts is studied. Indeed, as parts reach higher densities, the influence of the size and shape of pores become dominant on the mechanical performance and particularly fatigue resistance of the parts. Water atomized powder mixes containing different particles sizes of ethylene-bis-stearamide (EBS) lubricant were compacted both on a laboratory press and on an industrial mechanical press at higher speed rates. In addition to compressibility curves and static sintered mechanical properties, complete ejection curves and fatigue tests results are presented.