The Effect of Superfinishing and PVD/CVD Coatings on Torque and Temperature of SAE 52100 Rolling Element Ball Bearings Under Starved Lubrication Conditions

This paper reports on tests carried out using a bespoke high-cycle rolling contact test facility based on a thrust ball bearing configuration. The test machine is instrumented for temperature, torque, vibration and speed measurement. Following our recent publications, this paper concentrates on the rolling contact behaviour of coated and uncoated counterfaces under starved lubrication conditions. Cr2N and WC/a-C:H coatings deposited by PVD and hybrid PVD-CVD processes, respectively were tested. In addition, the effect of vibratory superfinishing on rolling contact, both in isolation and as a surface pre-treatment prior to PVD coating, is investigated. Data are presented illustrating the benefits provided by surface modifications under these extreme operating conditions and their ability to delay the onset of catastrophic bearing failure in the event of lubricant starvation.