This work has evaluated the influence of load and type of lubricant on the thickness of the elastohydrodynamic (EHD) film and the rolling-contact fatigue lives of AISI 521 00 steel balls. The lubricants studied have various viscosities and included two mineral oils and five synthetic oils from three families. Firstly, the central film thickness was determined in order to predict the lubrication regime. The stress-number of cycles fatigue curves were then calculated by means of Weibull plots, and the fatigue mechanism was evaluated.
The test machine used for the analysis was a Seta-Shell1980 four-ball EP lubricant tester. The 12.7 mm diameter test balls were made from a single batch of carbon-vacuum-deoxidised AISI 52100 steel with hardness RC65.
Elastohydrodynamic film thickness estimation was carried out using pressure-viscosity coefficients (a). In this study, to calculate a new interferometric technique, ultrathin film interferometry, was employed to measure the film thickness. A practical method was developed for evaluating EHD, mixed film, and solid lubrication processes. Micrographic mapping and energy dispersive spectroscopy (EDS) were used to analyse the rolling track of the test balls.