Evaluation of a polyethylene lubricant for aluminum P/M applications

Lubricants are generally admixed with metal powders to facilitate compactio n and to minimize forces during ejection of the part from the die. In order to optimize the mechanical properties of aluminium components fabricated b y powder metallurgy, the lubricant should not impede the formation of inter particle contacts during compaction. Also, it should burn out cleanly at re latively low temperature, (420 degrees C) to avoid reactions between alumin ium and the lubricant or decomposition products. Here, the effect of admixi ng a polyethylene lubricant on the compaction and ejection of aluminum allo y powder compacts fabricated from spherical powders has been assessed. This polymer has adequate lubricating properties and permits the compaction of aluminium powder without die-wall lubrication. Components fabricated with p olyethylene exhibit significantly higher green and sintered properties than components fabricated with a conventional amide wax lubricant.