Split balls

I have seen this before and I was told it is a manufacturing fault. The balls are made in a two piece mold and the break is at the parting line.

Did you try a search of this site? I'm sure I have seen similar photos and would guess that it was ether here or on the old reliability-magazine.com website.

Oli had been kind enough to archive that site and apply a search engine but I'm not sure he still has it in operation.

One of those old "Ask Walt" publications had something about split balls, I think, but I kind of recall it probably was the final stage of prett severe overheating so the balls were deforming, growing in size and a void was forming in the center

In this link I had summarized some history on craters and provided links to previous threads:
http://maintenanceforums.com/e...=591108461#591108461

You may find more searching, on both craters and balls splitting open.

And Oli keeps the old board alive even today. (Thanks Oli!!!!)

http://www.vtab.se/PHP-NBoard/...ules.php?name=Forums

I would recommend to register with his site and use his search feature.

Here is a list of threads from the old boards containing "crater"
http://www.google.com/search?q...IE-SearchBox&ie=&oe=

I would suggest that annual vibration readings aren't sufficient. You got lucky to catch it before it came apart.

Good point.

It is a bizarre failure.

I take it the bearing looked severely overheated in the as-found condition?

Dan – what’s an “ask Walt” publication? Walt Strong?

quote:

I have seen this before and I was told it is a manufacturing fault. The balls are made in a two piece mold and the break is at the parting line.

I have a hard time picturing the mould parting line scenario, but you never know. fwiw manufacturing fault makes sense to me.


The world according to electricpete (*): the ball splitting-in-half failure is clearly a brittle failure. The crater type mark is probably a brittle failure also. The balls are not supposed to be brittle. Therefore suggests either manufacturing defect which did not result in correct material properties, or else embrittlement from some mechanism in service.

For ball splitting in half, the entire ball needs to be brittle.
For crater defect, only the surface needs to be brittle.
I doubt there are many in-service embrittlement mechanisms that can embrittle the entire ball, unless hydrogen is present somehow.

* take it fwiw, I'm no materials guy.