Action of a femtosecond laser generated micro-cavity passing through a circular EHL contact

The increasingly severe operating conditions of lubricated contacts cause a decrease of the ratio of lubricant film thickness to surface roughness. In order to avoid a reduction of their durability, laser surface texturing is a promising technology allowing to optimize the surface micro-topography. The present work studies the phenomena generated by the passage of a single micro-dimple in an EHL contact. Thus, circular micro-cavities with various diameters and depths have been created on the contacting surfaces of an EHL tribometer by a femtosecond pulse laser, and measured using white-light interferometry. The lubrication phenomena induced by the passage of the micro-cavities were studied experimentally using the EHL ball-on-disk apparatus. The results obtained highlight significant modifications of the film thickness distribution due to the micro-dimples passing through the contact, acting as lubricant micro-reservoirs.