Correlation of 3-D Precision Machined Surface Topography With Frictional Response

Precision surface finishes are used in a wide variety of applications. From bearing races and rolling elements to parallel slide ways, the functional characteristics of these surfaces are critical to their performance. Experimental trial and error has shown that certain surfaces outperform others in certain applications, but the specific surface characteristics that make this true are yet to be fully understood. The present paper addresses this issue through a detailed three-dimensional topographic analysis of different precision finished surfaces and correlation with their frictional response. Experiments are conducted to investigate the effect of surface type (Isotropic Finished, Ground, Hard Turned and Honed) and relative surface speed on the coefficient of friction in rolling/sliding contact. Utilizing white light interferometry measurement of the surfaces, different 3-D topographic parameters such as RMS deviation, density of summits and texture direction are obtained and their correlation with the experimentally obtained coefficients of friction is examined. Results show that the 3-D amplitude parameter S_q (RMS deviation of surface) and spatial parameter S_ds (density of summits) play an important role in determining the frictional behavior of the surfaces studied.