Estimation of lubricant film thickness in rolling contact

On-line monitoring plays an important role in lifetime management of machinery. An especially interesting element of machinery is the lubricant, since it separates two vulnerable surfaces from each other. The properties of the lubricating films are decisive considering the machinery lifetime. The present paper introduces a regression model that has been developed for evaluating film thickness in rolling contact based on parameters such as viscosity, water content of lubricant, temperature, pressure and rolling versus sliding ratio. The film thickness measurements were conducted with an optical interferometer. The measured results correlate well with the model. By applying a similar model it may be possible to develop a practical tool for lubrication condition monitoring. It may be possible to make advanced statements on lubrication quality by combining direct and indirect information from different sources within the machinery. In the present paper different approaches will be discussed.