Understanding Powder Behaviour in Uniaxial Cold Compaction through the Data Recorded by the Press

摘要

This work is part of a large project started several years ago, aimed at using the data continuously recorded by a 200-t SACMI industrial press, without any additional device, to describe powder behaviour during uniaxial cold compaction. This innovative approach, through the accuracy and reliability of the data, allows highlighting the relationships between real compaction parameters and the characteristics of green parts. Forces and displacements recorded during the compaction cycle have been processed, and the main mechanisms determining powder densification have been highlighted. Different compaction strategies have been used to derive the compaction mechanics relationships, and the distribution of axial and radial stresses from which density distribution arises. The influence of different variables was studied, such as powder mix, geometry, particle size, and lubricant type and amount. The results of the study have been used by SACMI, the industrial partner in this project, to tune the pressing algorithms thus improving the pressed parts characteristics (geometry and density) in order to obtain a fully adaptive pressing process.