An Experimental Investigation Into the Effect of Lubricant on the Local Film Thickness of Artificial Roughness Features

The lubrication of rough surfaces has been a focus of researchers in the field for many years now. A good deal of work has been carried out either on the experimental or on the theoretical sides of the research. From the experimental point of view it is obviously more convenient to study the lubrication of artificial roughness features such as ridges, bumps or dents rather than real, random roughness. The advantage of model roughness features is that they are well individualized, located, and characterized, thus a comparison of the surfaces geometry inside and outside an elastohydrodynamic contact can be made. The studies carried out so far have focused on the effect of the geometry of the features and that of the entrainment speed. No detailed experimental work on the effect of the lubricant properties on the behavior of the EHD films has been performed, to the authors’ knowledge. The present study uses the optical interferometry method to measure the EHD film thickness between a flat disc and a ball on which artificial ridges have been sputtered. Two lubricants, with different viscosity and pressure/viscosity coefficient are used in a range of pressures and entrainment speeds.