NSK has developed two products, the RHP Ultra high speed, precision
bearing and Spinshot bearing with lubrication system, to cope with the
rapid temperature rise in machine tool spindle bearings running at very
high speeds. In its steel ball version, RH Ultra achieves speeds up to
2.5 x 106 dmN with oil/air lubrication, and a hybrid version with ceramic
rolling elements offers a 30% increase on this speed. For even higher
speeds, and hence temperatures, Spinshot comes into its own. The Spinshot
lubrication system, which uses oil/air rather than oil jets, enables
NSK’s EX Robust series bearings to sustain speeds well beyond 2.8 x 106
dmN. It also reduces costs by allowing the spindle structure to be
simplified, and also reduces oil consumption, which has an environmental
benefit.