According to NTN-SNR, the design principle of their air cooling spacer for spindle bearings is the integration of an air inlet in the spacer to lower the inner ring temperature and therefore reduce the temperature differences between the inner and outer rings. As the French company explains, the air inlet angle on the nozzle has been developed for optimal, smooth and unidirectional diffusion. This system reportedly helps to reduce preload increase due to temperature decrease. As a result, the manufacturers maintain, a 20-percent increase of maximum speed is achieved and it is now possible to raise the applicable preload for greater rigidity by a factor of three. In addition, the concept is said to ensure low noise levels.
Spindle bearing with air cooling spacer
With cooling nozzles in an intermediate ring or spacer, NTN-SNR reduces the temperature difference between the inner ring and outer ring in the spindle bearing. This is claimed to increase the speed by 20 percent.