The Influence Of Lubricant Type And Amount On Warm Die Compaction Mechanics Relationships

The mechanics relationships describing powder behaviour in uniaxial cold compaction have been derived in previous work on the basis of experimental data, as affected by many different variables in the compaction process. The influence of geometry, chemical composition, compaction strategy etc. were investigated in depth. This work focuses on warm die compaction, which stands for an interesting opportunity to increase density, also obtaining more homogeneous density distribution. Cylindrical specimens have been produced using a commercial diffusion bonded low alloy steel powder, to which different lubricants, in different amounts, have been added. The influence of type and amount of lubricant has been directly highlighted by the comparison of ejection force and energy. Axial and radial spring-back have been also evaluated. A deeper knowledge of the behaviour of the different powder mixes in warm die compaction has been obtained comparing the derived friction coefficients and constitutive models.