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News Release

November 11, 2009

Development of long-life bearing resistant to electrical corrosion(*1)for fan motors

JTEKT Corporation has developed and begun commercial manufacture of a bearing for fan motors in which electrical corrosion has been prevented, enabling long life.

In recent years, there have been demands for fan motors with lower noise and longer life. Fan motors are used in refrigerators, ventilation systems and a wide variety of other machines and devices, and often they are required to operate 24 hours a day. With such harsh usage conditions, there are many cases in which grease deterioration and electrical corrosion occur in the bearing, causing noise life to be reached prematurely. Such bearing corrosion not only shortens the fan motor’s life but also can lead to damage of the machine or device itself.
 To resolve these problems, JTEKT has developed a bearing in which electrical corrosion is prevented that enables a fan life of a minimum of 100,000 hours at an ambient temperature of 60℃.

Features of developed product

■ Use of ceramic(*2)as rolling element material
  • Grease life lengthened and electrical corrosion prevented by use of ceramic as the bearing material

■ Use of ultra-light contact, heat-resistant rubber seal
  • Low torque achieved by seal lip configuration optimization and ultra-light contact between rubber seal and inner ring
  • Rubber material with heat resistance up to 140℃ achieved
Features of developed product
■ Use of newly developed long-life grease
  • Grease with long life achieved by suitable mixture of base oil(ester oil + ether oil) and thickening agent (lithium soap)
    (*1) Electrical corrosion
    This mode of bearing damage occurs in the case of applications wherein an electrical potential difference exists between the bearing inner and outer rings during motor rotation. An electrical current flows between the inner and outer ring running surfaces and the rolling elements via the grease’s oil film, causing the bearing interior to be damaged and noise life to be reached.
    (*2) Ceramic
    Through a joint development project, JTEKT and Toshiba Corporation in 1984 succeeded in commercializing the world’s first bearing made of ceramic (silicon nitride material). Ceramic possesses such advantageous characteristics as being nonconductive, heat-resistant, lightweight, and nonmagnetic. By the use of ceramic as the rolling element material, the flow of electrical current between the inner and outer ring running surfaces and the rolling elements is prevented, which is extremely effective at preventing electrical corrosion.