Limiting speeds and operating temperatures of fixed preload large bore angular contact ball bearings for machine tools

Because of the ability of angular contact ball bearings to support both rad ial and axial loads and operate at high speeds, they are used widely to sup port machine tool spindles. The limiting speed of angular contact bearings depends on a number of factors including the type of bearing arrangement, p reload, lubrication and bearing spacing. Preloaded back-to-back angular con tact ball bearings are commonly used and in this paper the limiting speed o f such an arrangement is considered together with a simple method for estim ating speed factors which is shown to agree with actual experience. Also, little information is available on the operating temperatures of larg e angular contact bearings and so the effect of lubrication conditions on t he limiting speed of angular contact bearings of 200 mm bore are investigat ed. In particular the design of the lubrication nozzle is shown to have a s ignificant influence on the bearing operating temperature.