-
PLAIN BEARING FAILURE
1.0 Lubrication breakdown
-
Lubrication breakdown index
1.4 Typical wiping failure
| Click on photograph to enlarge | |
 |
Wiping of journal bearing showing resolidified white metal in the oil groove |
| Main Characteristics | The photograph shows a typical wiping failure with the molten white metal from the bearing surface solidifying in a cooler part of the bearing, in this case the oil supply groove. |
| Cause | Wiping is caused by loss of the hydrodynamic lubricating oil film during running. There are a number of reasons why this can occur. These are discussed in the summary sheet at the end of this Section. For more information on causes of lubrication breakdown and possible actions to take, see Lubrication breakdown - Summary |
| Note | The resolidified white metal can often be peeled off from the surface. Measuring the thickness of the bearing shell at various positions axially and circumferentially can show the exact position of the shaft when the wiping took place and this can in some cases aid the failure diagnosis procedure. |
| Possible Confusion with Other Types of Damage | Wiping can be a secondary event initiated by fatigue damage or electrical erosion reducing the effective load carrying area of the bearing. The signatures of these failure mechanisms (fatigue, electrical erosion) are described in the appropriate sections and should be looked for, particularly in the nominally unloaded parts of the bearing. |
| Comment | Do not change to a bearing material with higher load-carrying capacity unless it can be established that failure has been the result of inadequate strength in the white metal. Treating the symptoms is not the way to provide a cure. The cause of failure must be identified |