Roller bearings `last twice as long`

Following an investigation into the mechanism that causes slippage in spherical roller bearings, NSK has developed a new series of high-performance SRBs which, it claims, deliver twice the running life of conventional bearings of a similar size, while offering a maximum limiting running speed up to 20% faster.

The HPS Series SRBs, initially available in 42 sizes with outer diameters from 80-260mm, are said to cut energy and maintenance costs and to allow smaller product designs.

SRBs are self-aligning and have high load capacities, but some slippage usually occurs at the contact surface points between the raceways and the rollers, creating friction and eventually leading to damage due to surface fatigue. NSK`s studies have revealed that that the friction can be cut by controlling the motion of the rotating rollers. It does this by giving the surface of the outer ring a special surface treatment.

NSK has also applied a special nitriding surface treatment to the bearings` precision pressed-steel cages to reduce wear in harsh operating environments. The treatment is said to produce a finer, harder, more uniform surface than conventional nitridng.

The company also claims to have overcome the problem of the cage becoming distorted by the high-temperature nitriding process. This allows the bearing to be run at limiting speeds up to 20% faster than normal, without suffering from cage wear.