Rolling Element Bearing Identification 4

[BrianBT]

A 2MW shaft alternator was overhauled and new ball bearings fitted. The DE bearing was identified as an SKF 6232 MC3. This bearing was also the thrust.
After one hours run time this bearing failed.
After disassembly although the bearing was stamped as an SKY the design was unknown to them and was certaily spurious. However the design was such that it would have almost certainly cost more than a standard bearing to produce.

Instead of plain balls the elements were oval shaped with a 'button' on the long axis which located in a complimentary depression in the cage thus allowing the elements to rotate in one axis only and therefore could not accept the thrust when the alternator was running

Anybody have any ideas about identifying this bearing as the bearing distributor who supplied the bearing only reacts with a 1000yard stare when we try to quiz him

 

[Mendit]

A 6232 designation is a single row deep groove conrad bearing. M, indicates a machined bronze cage and the C3, is greater clearance than standard. These are not often used as a thrust bearings but can be used as a positioning bearing, where thrust load is less than the radial loads.

What you explain sound like a thrust bearing from vertical motor like a 29232 which has very little radial capacity and lots of thust in one direction only.

 

[Mendit]

Please disregard my first post
This bearing looks like a 6232 MC3. I have seen this type of failure before.
Scenario.
Motor rebuilt and set on line, vibrations verified OK alignment checked ok. everything doing just fine. next hour, total failure. Experienced forensic inspection.
Inner race turned blue (just like your picture)
Ball deformed (Similar to your picture)
Conclusion the fit of the inner race to the shaft was less than required interferance. Bearing sees elevated temperatures due to heat migration. fit to shaft lets go. shaft spins inside the bearing race, rapid heating, balls deform, cage breaks up. Failure. All takes place in 5 minutes or less. Question your repair company for the fit (amount of interferance) of the bearing to the shaft before install

 

[BrianBT]

The results came back from skf who as expected indicate this was not one of their bearings despite markings indicating otherwise

following on from the events above the new bearing fitted has seen a steadily increaseing running temperature. More significantly the bearing has temperature fluctuations of several degrees which occur without obvious external influence.

I have suggested that this is caused by the bearing being able to move within its housing/shaft fit. I have indicated that the owner consider the repairs carried out to have failed and to start to properly plan for a period of downtime