PhD Position: Film thickness in Grease Lubricated Roller Bearings

The SKF University Technological Centre for Grease Lubrication at the University of Twente has an opening for a PhD candidate. The goal of this 4-year project is to measure and model film thickness in grease lubricated cylindrical roller bearings. This requires a thorough understanding of Elasto-Hydrodynamic Lubrication (EHL), thin film lubrication properties of oils, and grease lubrication mechanisms. The overall result is a semi-empirical model for predicting film thickness in cylindrical roller bearings for various greases, under various conditions. This project is executed in close collaboration with SKF, a leading global bearing manufacturer, and Shell, a leading global base stock and lubricant manufacturer.

The Challenge

Bearings are the most widespread machine elements after nuts and bolts. There are more than 50 billion bearings operating in the world at any time. 80-90% of bearings are grease lubricated. The reliability or life of a grease lubricated bearing is dominated by the quality of the lubricating film that separates the rolling elements (balls or rollers) from the rings. The quality of the film is determined by its thickness and 'lubricity'. The film thickness determines the contact 'intensity' from the stresses caused by asperity interaction. Grease lubrication mechanisms can be complex. Unlike oil lubrication in which the contacts are fully flooded, grease lubricated contacts are often 'starved' (with no lubricant in some regions of the contact). Severe starvation can lead to 'parched lubrication'. The challenge here includes developing a consistent model and practical methodology for determining film thickness in cylindrical roller bearings (CRBs).

You will:

• study lubrication mechanisms in grease lubricated roller bearings;
• study grease churning and bleed behavior in a roller bearing;
• design an experimental test set-up for film thickness measurements;
• measure film thickness in cylindrical roller bearings under various operating conditions;
• further develop a film thickness model for cylindrical roller bearings;
• closely collaborate with your research team colleagues at the University of Twente;
• finish your research with a PhD thesis and publish your work in academic journals and at conferences.