Effects of solid graphite lubricants for powder compaction

Abstract

In this paper, the mechanical characteristics for metal powder compaction with the addition of graphite powders are investigated to reduce the friction generated during the powder compaction process. The discrete element method model is developed for powder compaction with powder mixture containing steel-graphite and copper-graphite. Compaction experiments are performed for the validation of the model. Parameters involved with mixing conditions such as graphite mixing and graphite size ratio and its effects on compressive characteristics are explored. Optimal values for mixing conditions are defined. Also, the effects of powder mixing parameters are investigated through analysing stress transfer ratio from top to bottom punch and compressive force distribution throughout the powder compact. Significant improvements in mechanical properties are observed with the addition of graphite lubricants. Improved stress transfer rate by 57% (steel) and by 44% (copper) are obtained and decreased standard deviation of compressive force by 85% (steel) and by 67% (copper) are observed.