The series makes it possible to adapt the speed suitability and robustness of the spindle bearings to customer requirements. Left: Spindle bearings of the HCM variant are equipped with ceramic balls, the bearing rings are made of 100Cr6 rolling bearing steel. Right: The bearing rings of the VCM variant are made of the newly developed high-performance material Vacrodur.
Schaeffler
The performance capability and productivity of machine tools are significantly defined by the main spindle, whereas the suitability for high speeds, rigidity, and robustness against operational influences are defined by the spindle bearing. Important development objectives for the new spindle bearings included an internal construction with particularly optimized friction behavior and a high tolerance towards rapidly changing thermal operating conditions such as those that frequently occur in motor spindles. The optimized construction greatly reduces the rise in bearing preload caused by influencing factors such as interference between the bore and the bearing, high speeds, and large temperature gradients between the shaft and housing.
The new series is available in the three different versions: M, HCM, and VCM. The balls and rings of M-variant are manufactured from the proven 100Cr6 rolling bearing steel. HCM-variant spindle bearings are equipped with ceramic balls and rings made from 100Cr6 rolling bearing steel. Spindle bearings in the VCM-variant also feature balls made from ceramic material, but with bearing rings made from the newly-developed Vacrodur high-performance material. This high-performance steel possesses a range of characteristics that make it ideal for the application as a spindle bearing. With regard to the endurance limit, Vacrodur withstands up to 35 percent higher pressures than the proven 100Cr6 rolling bearing steel. A 2.4-fold increase in the dynamic load carrying capacity in comparison to standard 100Cr6 rolling bearing steel – which represents a 13-fold increase in the bearing’s nominal rating life – has been verified under good lubrication conditions in tests. There is even a 25-fold increase of the operating life under insufficient lubrication conditions.