Fan motors, extensively used in personal computers, game consoles, etc., are required to have a minimum life of 60,000 hours at potentially high operating temperatures (80 to 100°C). Roller bearings are normally specified for such long life requirements because PM self-lubricating bearings typically have a life of less than 30,000 hours in such applications due to loss of the conventional polyalphaolefin lubricating oil through evaporation at high operating temperatures and also leakage.
A new self-lubricating PM bearing design developed by Hitachi Powdered Metal, a division of Hitachi Chemical in Japan, in combination with the use of a newly developed polyol ester lubricating oil, is now able to challenge roller bearings in long life fan motor applications.
The company states that by incorporating three helical grooves (100 helix) into the Fe-Cu-Sn-P-C sintered bearing, the sealing and lubricating function allows the friction coefficient of the bearing to be optimised and improved. Furthermore, the use of the polyol ester lubricating oil has reduced oil evaporation at high temperatures by some 40%.
By making the lubricating oil flow towards the fan motor’s closure side, the newly developed helical-grooved bearing prevents oil from leaking out of the discharge side.