A new angular contact ball bearing has just been developed by bearing manufacturer Schaeffler to prevent the failure of ballscrews which are used in short stroke applications. Those bearing which are particularly at risk of false brinelling are those which are used in medical equipment.
False brinelling occurs when the lubricant film which is separating the rolling elements from the raceways dissipates. This can be due to the lack of motion of the components or when the pivot angle is small. It usually occurs in applications which use as short stroke ballscrews.
The incidence of false brinelling causes fretting corrosion at the point where the ball-to-steel contact is unprotected. It’s at this point that the raceway surface starts to corrode. If the bearing is not used for some time the rolling elements can actually fuse to the raceway which will lead to failure of the device.
When the strokes on a ballscrew are very short or when the screw remains stationary for protracted periods of time the incidence of false brinelling is much greater.
The new angular thrust ball bearing from Schaeffler uses ceramic rolling elements so metal-to-metal contact is eliminated.