Measurement Of Lubrication Oil Film Thickness In A Fixed-Incline Slider Bearing

This master thesis is mainly concerned with the measurement of lubrication film thickness in a conformal contact formed by a fixed-incline slider bearingA test apparatus is introduced developed for the measurement of lubricating oil film thickness in an conformal contact. Lubricating hydrodynamic films are generated by a stationary precision polished slider flat loaded against on a rotating transparent disc, and the minimum film thickness is measured by interferometry. The slider flat is high precision polished with high reflectivity, and the transparent disc is coated with semi-reflective film. With a flexible slider holder, the slider flat can be positioned in such a way that a desired inclination with respect to the disc plane, that is a geometrical wedge, can be obtained and kept unchanged during operation. Measurement errors of the film thickness and their origions were analyzed and an error correction shceme has been presented. An adjustment method was presented to achieve a stable inclination angle between the lubricated planes when the system is running, and a mechanical model was presented to account for the adjustment shceme. Using the test apparatus, lubricating films can be obtained under prescibed inclinations, loads, velocities and oils. The credibility of the measurement system is demonstrated by the good correlation between the experiments and the theoretical results. The test apparatus provides a new approach for evaluation of lunbricating films in conformal contacts.Some experimens were carried out to show the influences of liquid/solid wettability on thin hydrodynamic lubrication film thickness by the test apparatus described above. The liquid/solid wettability can be differentiated by the contact angle of the lubricant to the lubricated surfaces, and different slider materials and lubricants can generate interfaces of different wettability. Under a fixed load and a constant slider inclination angle, the film thickness at different entrainment speeds is measured. And when the interface of weak wettability is used, significant film thickness variation can be found.Numerical calculations of the lubricating film thckness of a fixed-incline slider bearing have been carried out in the study. The film thickness and pressure were obtained for different entrainment speeds and loads. The numerical results show good correlation with experiments qualitatively. To understand the interface wettabily effect observed in the experiments, analyses by the wall slippage effct is presented.