On the Squeeze Effect of Lubricant Between Two Rough Surfaces

The clarification of the squeezing mechanism of lubricant, which flows between rough surfaces, is quite important for the improvement of the dynamic characteristics of sliding elements, and for the elimination of stick-slip vibration. In the present study, the surface roughness effect on the squeezing mechanism is examined. In the first place, the approximate equation of squeeze flow is introduced for flat surfaces. Then, the approximate equation is extended to the case of rough surface. The calculation of lubricant squeezing by the extended equation agrees well with the experimental results in both cases of circular and rectangular surfaces. The squeeze coefficient is the criterion for the load carrying capacity of the contact surface due to the lubricant squeezing. Then, this coefficient is obtained as a function of surface topography and oil film thickness. The representative equation of the squeeze coefficient for the rectangular surface is the same as for the circular surface. The fundamental information is important to improve the dynamic characteristics of sliding elements.