Experimental Techniques for Analysis of Die Pressing and Ejection of Metal Powder

Abstract

The die pressing test is widely used to investigate the mechanical behaviour of powders. However, analysis of the results may be problematic because of the effects of powder-wall friction and the analysis requires measurements of the radial stress applied to the die. Two die pressing devices, allowing continuous measurement of this stress during compaction (either directly or through the deformation of the die), are presented. From the results obtained for an iron powder, an analysis of each step of the die pressing process (loading, unloading, and ejection) is proposed. The three models derived in this manner provide estimates of intrinsic properties of the material and of the powder-die friction coefficient. The validity of the analysis is discussed with reference to the results of finite element calculations. PM/0710