A major trend in the machine tool industry is for higher maximum spindle speeds. In addition, machines are being required to perform a wider variety of tasks and undergo frequent tool changes. Under such conditions, excellent high-speed performance is imperative and spindles must accelerate and decelerate faster. During periods of rapid acceleration or deceleration, spindle ball bearings are subjected to severe thermal load conditions. These conditions are caused by drastic changes in the ambient environment that result from heat generated by the motor, housing cooling and other factors. Performing well under such conditions and being capable of higher speeds than conventional precision bearings, the ROBUST Series ball bearings provide solutions for high-speed spindles of the 21st century. NSK Ball bearings can be categorized as Deep Groove Bearings or Angular Contact Bearings. Deep groove bearings are further identified as single or double row, and Conrad type or filling slot type. Specific characteristics of each type are identified by the bearing number. Super precision Ball bearings have relatively thin rings and will take up the shape of the mating shaft or housing, thus transferring any errors in form to the bearing raceway. Abutment faces on the associated parts must be square to the axis of the shaft, or the bearing rings may be misaligned, resulting in increased run out and higher running temperatures, particularly on high-speed spindles.
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