Determining the Pressure Dependence of Lubricant Viscosity by Roughness Measurement of Rolled Strip

Abstract

The pressure dependence of lubricant viscosity can be determined by the average lubricant film thickness in a series of rolling test using smooth roll. The tests are conducted in the mixed lubrication regime so that the average film thickness is identical to the average depth of the surface valleys on the rolled strip and a unique, simple analytical formulation inferring the average film thickness from roughness can be obtained. Benchmark rolling tests using different lubricants of known properties, strip materials, reductions, and surface roughness patterns are performed to verify the formulation. The experimental result is concordant with the theory with small errors.