Effects of a thickener structure on grease elastohydrodynamic lubrication films

The effects of the thickener structure and base oil viscosity on the grease film formation in rolling point elastohydrodynamic contacts have been disc ussed on the basis of direct observation using the optical interferometry t echnique. Three different types of diurea greases without additives have be en used as test greases. As the base oils three kinds of ether-type synthet ic oils having similar molecular structures but different viscosities were used. The film behaviour of fresh greases has also been compared with that of the degraded greases. It has been found that the behaviour of grease ela stohydrodynamic lubrication films is basically influenced by the thickener structure and base oil viscosity. The adhesion or deposition of the thicken er on the contacting surfaces and oil starvation which affect film formatio n depend on the thickener structure, base oil viscosity and rolling speed. Furthermore, it has been suggested that there is an optimum temperature whi ch gives a maximum film thickness according to the consistency of the greas e.