Tokyo, Japan, October 18, 2011 – NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Norio Otsuka) today announced that it has developed a ceramic ball bearing made of a new material that prevents galvanic corrosion as a bearing for fan motors used in devices such as air conditioners. Quietness is maintained in the new product for a long time by preventing bearing damage from electrical corrosion that occurs due to the effects of inverter control devices. NSK is aiming for annual sales of the new product of 3 billion yen by fiscal 2013.
Fan motors are widely used in products such as air conditioners, clean room equipment, air cleaners, and ventilation systems. In recent years, the shift to inverter-controlled motors has progressed in order to save energy on top of having quiet fan motors. With invert control, however, voltage variation causes current to infrequently flow through the inside of the bearing, resulting in damage called electrical corrosion*1, which may lead to increasing noise from the bearing. Silicone nitride ceramic balls have conventionally been used as a countermeasure to electrical corrosion. NSK has now developed an anti-electrical corrosion bearing that is perfect for fan motors and that uses ceramic balls made of a new material with higher productivity.
*1 When electric current passes through a bearing, arcing and burning occur through the thin oil film at points of contact between the race and rolling elements. The points of contact are melted locally to from “fluting” or groove-like corrugations which are seen by the naked eye. The magnification of these grooves will reveal crater-like depressions which indicate melting by arcing.
The new product will help improve the reliability of fan motors through the following two points:
*2 False brinelling: A phenomenon in which friction is generated at the contact area between the race and rolling element due to vibration and oscillation.