The Use of Laminar Lubricants in Compaction Processes

Abstract

A punch penetration shear test has been used to support the theory of orientation of layers within the crystal lattice as the lubricating mechanism of laminar solids. Under high applied loads, this orientation is prevented, thereby causing a high value of the shear strength. The increased shear strength is manifest in an increased coefficient of friction under high loads, as found experimentally in the die pressing of solid plugs of talc and graphite. The use of these solids as lubricants in compaction processes cannot be justified at high constraining loads, where the relative density of the compact is high.