Greased angular bearings `last five times as long`

Angular contact bearings, widely used to support machine tool spindles, do not usually have a large enough cross-section to machine a groove to hold a grease seal. Now, FAG`s Barden division claims to have overcome this limitation with a sealed version that it says will last up to five times longer than standard angular bearings.

To achieve this, FAG uses a shallower groove than normal and machines it into the narrow cross-section on the relieved side of the angular contact outer rings. This allows seals to be fitted to hold the grease and to keep contamination out from both sides of the bearing.

FAG claims that the seals have the same retention characteristics as standard seals but are fitted so that there is no contact with the bearing inner rings. This minimises friction and heating. It is also said to overcome the problem of ring distortion caused by radial pressure. In addition, it provides a grease reservoir between the seals and balls.

The 2RSD bearings are lubricated for life with the correct amount of grease applied to the bearing close to the contact zone. Users do not need to go through the time-consuming and messy business of washing out and regreasing before fitting the bearing.

FAG says that tests have shown that even after many hours of operation, the sealed bearings are still much cleaner inside than non-sealed types. In addition, air is unable to enter the bearing to dry out the grease, prolonging the bearing`s life.

FAG suggests that the new bearings, which are a direct replacement for standard angular contact types, will cut running and maintenance costs in machine tool applications. It adds that there are particular advantages when used with vertical or inclined spindles because migration of the lubricant is minimised, irrespective of the bearing position. The bearings are available with either standard or ceramic balls.

As well as savings in running costs, FAG says that the new system can cut initial costs in many applications, because the greased-for-life bearings can replace complex and costly recirculating oil lubrication.