A parametric study on oil/air lubrication of a high-speed spindle

The ball-bearing is widely used on many high-speed spindles due to its low starting friction and high load capacity. However, heat generation and dynamic loading caused by high-speed rotation have been obstacles for increasing the speed limit in many high-speed ball-bearing applications. Applying an appropriate lubrication and preload cannot be overemphasized. Recently, oil/air lubrication has been used on high-speed spindles because of its accuracy in oil quantity control and high cooling efficiency. However, an oil/air supply with inadequate parameters is undesirable. In this study, the performance of a high-speed spindle under different lubrication parameters and preloads was investigated. The Taguchi method was applied to study the effects of design parameters on the lubrication efficiency. This method can also be used to obtain the optimum lubrication conditions. The optimum operating conditions that create the smallest temperature increase were established. The effects of preload on the temperature increase, the thermal deformation and the static stiffness of an oil/air lubricated spindle were studied. The results provide a useful tool in designing a high-speed spindle with a small increase in temperature and sufficient static stiffness.