Fractured Bearing

[dArsonval]

Here are photos of a catastrophic bearing failure. Bearings broke down with multiple cracks like this are rare.
These are 2008 photos, and I do not recall what the root cause of this failure turned out to be.

The dirty brown appearance on the outside race tends to indicate the motor end bracket is/was out of tolerance...
and the rusty surface stems from the bearing moving around within the bearing pocket.

Any theories as to what forces were in action to ruin a bearing so effectively?

John

 

[jraef]

I’ve seen similar effects as the final outcome of EDM damage from operating on an inverter, then left unattended until there was a catastrophic failure. If you were to have looked at the inside races, you may have seen extreme fluting in a washboard-like appearance.

Usually before it results in fracturing, the extreme noise clues people in to the fact that something is wrong. But in some cases that noise is drowned out by the normal process noise or is ignored for the sake of production quotas.


" We are all here on earth to help others; what on earth the others are here for I don't know." -- W. H. Auden

 

[Compositepro]

From the color of the fracture surfaces it appears that the bearing race was cracked for a long time before it finally fell apart.

 

[romke]

With a failure like this it will be difficult to find the root cause. The forming of the cracks most likely will have taken quite a bit of time and during that time lubrication deteriorated and a lot of heat has been generated that lead to oxidation of the grease. As remarked by jraef the extra noise may have been drowned in other noises, until the bearing more or less exploded.

In cases like this i would not spend too much time trying to find the root cause, unless when it is a recurring failure. Finding the root cause in a situation like this is extremely difficult because due to the complex damage it will be very hard to tell with what it started.

 

[waross]

Not that difficult if EDM is the root cause.
If examination of the race shows signs of EDM damage then steps should be taken to protect the replacement.

Bill
--------------------
"Why not the best?"
Jimmy Carter