Pressing bearing sets together during hot mountingSuper-precision angular contact ball bearings are typically used in sets. When the bearings are heated, their bore diameter becomes larger and their width also expands. The larger bore diameter facilitates mounting.
When cooling, their bore diameter contracts to obtain the necessary (interference) fit. Their width also contracts and a small gap between the bearings can result. This gap can negatively impact the preload in the bearing set. To avoid this, the bearing inner rings should be pressed against each other while cooling (fig. 1) with an axial force that is slightly greater than the dismounting force. A force should never be applied directly or indirectly to the outer rings when pressing the bearings together.
Package markingsSKF super-precision bearings are distributed in SKF illustrated boxes (fig. 2). An instruction sheet, with information about mounting, is supplied in each box.
When selecting universally matchable angular contact ball bearings to make a set from existing stock, the package provides helpful information such as the mean outside and the mean bore diameter deviations from the nominal diameters as well as the actual bearing contact angle (fig. 3). Bearings with similar deviations and contact angles should be used together in a set.