What would cause my barely used green bearing to do this?
bearings are so well made today that even angular contact bearings are out of favor for a simple deep groove ball bearing.
Um, no.
"If the bearing needs to cope with a heavy axial load, an angular contact bearing should be used. These have a different internal design allowing them to handle much greater axial loads than standard radial ball bearings."
SMB Bearings
Back to the drawing (conclusions) board for you!
If you want to cite aerospace applications, go right ahead. I won't wait.
Congrats, you can google "ball bearing axial load".
SKFs standard for deep groove axial loading is 0.5 of C0 in a purely axial loaded situation, which is a worst case scenario for a ball bearing. Closest (in size) off the shelf deep groove is a 208, which has a C0 of 6070lb, which is 3000lb of axial load.
SKF
Aerospace doesn't use angular contact except in super specific circumstances, they have great axial loading, but they only carry load in a single direction. So you need to apply large amounts of preload on the bearing in order to ensure that there's never more axial force applied in the "wrong" direction. If you're in a situation where axial movement will be in both directions, which is common, it's not the appropriate choice. In addition, bearing life is obviously effected by heat. Bearing heat load is calculated by bearing diameter, speed, power and
load (which includes preload), all of that means that angular contact bearings are not an appropriate choice for a wheel bearing.
P&W uses deep groove ball bearings for axial load control on the five products of theirs I've worked on. J57, J75, JT9, FT4, PT8 and PW4000.
We currently use a mix of angular contact and deep groove bearings at work now, speed and ability to actively cool the bearing being the deciding factor. The move to angular contact is usually in the 3500hp+/10,000rpm+ range and requires hundreds of pounds of preload and oil flood lubrication to keep them alive with the heat load being applied to the bearing.
It's not just a simple, "angular contact has more axial capacity so it must be better."
