Ejection Performance of an Improved Die Wall Lubrication Technology Using Composite Lubricants

A new approach in the method of depositing an external lubricant on the die walls of a powder metallurgy press has been developed which allows the compaction of parts from mixes with no or minimal lubricant content. By heating the die to moderate temperatures (70°C 100°C) and using new composite lubricants, optimum thickness lubricant layers can be deposited allowing the compaction-ejection of difficult parts. Trials were carried out on an industrial press with measurement of the compaction and ejection forces for different parts and powder mixes. In particular, an iron-resin powder mix with no internal lubricant was pressed into rectangular shapes of different thicknesses and punch profiles. Mixes for high density applications were also pressed into rectangular shapes using die wall lubrication (DWL). The results are compared to those obtained with regular mixes containing 0.75% wax and special mixes intended for high density applications (low internal lubricant) pressed without the DWL.