Evaluation of a polyethylene lubricants for aluminium P/M applications

Lubricants are generally admixed with metal powders to facilitate compaction and to minimize forces during ejection of the part from the die. In order to optimize the mechanical properties of alominum components fabricated by powder mettalurgy, the lubricant shoold not irapede the formation of interparticle contacts during compaction. Also, it should burn out cleanly at relatively low temperature, (420°C) to avaid reactions between aluminum and the lubricant or decomposition products. Here, the effect of admixing a polyethylene lubricant on the compaction and ejection of aluminum alloy powder compacts fabricated from spherical powders has been assessed. This polymer has adequate lubricating properties and permits the compaction of aluminum powder without die-wall lubrication. Components fabricated with polyethylene exhibit significantly higher green and sintered properties than components fabricated with a conventional amide wax lubricant.