Ball screw supplier NSK (Tokyo) has come up with a new method for grinding the nuts employed in its products to lengths of 800 mm (1.4-times the length of conventional nuts). This was not an easy task it hastens to add, involving the development of a dedicated nut grinding machine. Longer nuts make it possible to increase the number of load balls in the nut, thereby increasing the maximum allowable axial load by a factor of 1.3 & the service life of the ball screw 2.8-fold versus nuts fabricated using conventional cutting processes.NSK also employs a dedicated design for ball circulation that employs a tangential pickup method using a proprietary deflector. This makes it possible to achieve high-speed rotation even with large ball screws over 140 mm in diameter and balls that are one inch in size. Performance as delineated by the unit dn (diameter (mm) x rpm (min-1) of up to 100,000 is thereby achievable.
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