Tapered Bearing Retainer, Shot Blast Trouble

[tbolony]

Tapered bearing cages are being degreased by a hydrocarbon (ISOPAR L) degreaser. After this process, the parts go into a shot blast. This is where the problem lies. Before the new equipment was installed there was not a problem. The parts are sticking together like a bunch of cups and are not getting shot blasted sufficiently. Some parts that are stuck together, however will get the proper shot blasting. It is only a select few that are insufficient. Test were performed to determine that the degreasing machine is the culprit. But the hundred dollar question is what is the machine doing to cause this condition? Different solutions were tried at no avail. Speeding up the tumbling in the shot blast was one attempt. If the problem is known then a proper solution can be carried out. Any ideas would be greatly appreciated. Thanks!

 

[sreid]

What is the cage material?

 

[tbolony]

The cage material is made from cold rolled carbon steel (JIS G3141 SPCC-SD).

 

[dimjim]

I am amazed that it does not happen in all cases. It seems like a natural effect that they would encase themselves periodically. You might try changing the size of the shot blast and see if that helps.

 

[tbolony]

dimjim, would you suggest a larger or smaller size shot blast? Currently, the grade being used is Grade S-110 which is very small. There is a different type which is basically steel chips instead of balls that may work. That particular grade is prefixed with the letter "G". Any suggestions to which one to try first? The next size larger (S-170) or the different type (G-50)?

 

[dimjim]

I was thinking larger but would stay with the same type.
If the shot were large enough, I do not see how they would cup together.