Analyses of the fundamental parameters of cold die compaction of powder metallurgy

The main object of this paper is to produce an expression relating the green density and porosity of the compact as a function of process parameters. The analysis takes into account the internal coefficient of friction between the particles and the powder/container interface friction, and the work hardening effect of the particles. A modified analytical expression for the yield compression stress based on the internal coefficient of friction and the shape factor of the particle was also introduced in the analysis. Experiments were performed on cold die compaction of powder of different particles, having sizes between 45 and 150 μm. The influence of the outstanding parameters of the P/M was analyzed and it was found that the internal, and the powder/container coefficients of friction play major roles in controlling the axial density distributions. Comparison between experimental and theoretical results of the green density and the total porosity distributions demonstrated remarkable agreement for all the tested conditions for different work hardening behaviour of the particles. In addition, and for the purpose of verification of the present theory, other published work was also compared and found to be in very good correlation with the predicted results. Other relevant parameters will also be discussed.