Surface textures for enhanced lubrication: Fabrication and characterization techniques

In hydrodynamic lubricated thrust load bearing contacts, commonly found in mechanical seals and bearings, 'engineered' surface textures have the potential to enhance lubrication in terms of reduction in friction, leakage and increasing load support. These surface textures or features are in the form of micron scaled posts or cavities having arbitrarily definable geometries. The height/depth of these features is of the same order of magnitude as the film thickness of the lubricated contact. This paper presents an overview of a photolithographic process for fabricating the deterministic asperities on a 'flat' stainless steel surface. The textured surface is then characterized using an optical profiler to evaluate the surface form error and edge rounding error in surface texture features. It was found that the circumferential waviness of the substrate was sinusoidal with amplitude of 0.2μm. When the micro features are lapped for height control, slight rounding around the edges of the features having an average radius of about 10% of asperity length is observed.