Lubricant Behaviors in the Compression-Friction Test of Strip Metals

Abstract

The lubrication mechanisms were investigated in a modified plane strain compression test where the friction is also measured by simultaneous sliding of one of the dies in the strip-width direction. Though the average film-thickness of lubricant trapped between tool and workpiece agreed well with the theoretical calculation based on the squeeze effect, the subsequent behaviors of lubricant seemed to change with the viscosity under the pressure given and the shear rate. Lubricants trapped in small pits on the deforming surface function predominantly hydrostatically when relatively low viscosity mineral oils or vegetable oils are used under relatively low pressures, but develop hydrodynamically considerable shearing stresses on the workpiece and thus even alter the surface micro structures when higher viscosity mineral oils are used under high pressures.