Ball Bearing Failure
Ball Bearing Failure
(OP)
Dear all,
Any idea what is the possible cause of the failure of this angular contact ball bearing? Attached is the photograph of the ball bearing 14 out of 15 balls have the similar pattern on the ball with the initiation site at the center and propagate radially like fatigue striation. The outer and inner raceway show microcrack and spalling but not as severe as the ball. They are 1 inch ball bearings.
Note: Why I could not upload the file...why doing this ...this statement came out.
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Anybody can help me...
Regards,
Happy New Year...
Any idea what is the possible cause of the failure of this angular contact ball bearing? Attached is the photograph of the ball bearing 14 out of 15 balls have the similar pattern on the ball with the initiation site at the center and propagate radially like fatigue striation. The outer and inner raceway show microcrack and spalling but not as severe as the ball. They are 1 inch ball bearings.
Note: Why I could not upload the file...why doing this ...this statement came out.
Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine.
Details: To enable the details of this specific error message to be viewable on remote machines, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "Off".
<!-- Web.Config Configuration File -->
<configuration>
<system.web>
<customErrors mode="Off"/>
</system.web>
</configuration>
Notes: The current error page you are seeing can be replaced by a custom error page by modifying the "defaultRedirect" attribute of the application's <customErrors> configuration tag to point to a custom error page URL.
Anybody can help me...
Regards,
Happy New Year...





RE: Ball Bearing Failure
RE: Ball Bearing Failure
I could not post the attachment...I had tried many times to upload my file but the error message came out. I do not know the reason. I will try again.
Sorry for the inconvinience.
RE: Ball Bearing Failure
Did you try the attachment link on the tool bar where you post?
RE: Ball Bearing Failure
metengr
Yes I had tried using toolbar..but still failed.
RE: Ball Bearing Failure
I strongly suggest looking in the chapter in the old (i.e. 9th or Red) edition of ASM Handbook on bearing failures. It is the best reference I have seen for such systemic analysis of bearings and will help you identify the mechanism or potential mechanisms of failure for your system. Good luck!
RE: Ball Bearing Failure
Thank you ...noted. Will look for the book. Most of the failure analysis work on bearing dealing with path pattern either on the outer/inner raceway..not much on the ball. In my case the ball spalled badly but the raceway exhibited microcrack probably due to subsurface/surface initiated fatigue.....
RE: Ball Bearing Failure
The image showing the initiation site on the other ball, The spalling then propagated radially. This image shows one initiation site. Other balls had 2 or 3 initiation side and propagated radially.
RE: Ball Bearing Failure
RE: Ball Bearing Failure
RE: Ball Bearing Failure
RE: Ball Bearing Failure
RE: Ball Bearing Failure
RE: Ball Bearing Failure
Happy New Year
RE: Ball Bearing Failure
RE: Ball Bearing Failure
What is the info stamped and etched on the sides of the races?
Including country of manufacture.
Pictures of the races and bearing separator/cage would be helpful.
Usually angular contact bearings exist in pairs, or even 3s and 4s.
Please Post pictures of the other bearings, and the housings and shaft as they were disassembled, and after being gently cleaned
How are the bearings >> supposed<< to be lubricated ?
In the first picture there is debris on the blue towel. If that came from the ball, I'm thinking the lubricant is charred or has turned to varnish.
And the ball looks quite dark, like things got pretty hot
What is the machine history?
Why did you decide to take it apart?
Did you build this machine?
If not, what is the manufacturer's name, make and model?
RE: Ball Bearing Failure
From where does the arc strike come from ...Is it similar to electrical leakage?
RE: Ball Bearing Failure
Another failure .already mentioned is caused by welding on the application without correct grounding cable position.
All this is supposition without more information.
The most common failures of bearings are caused by lack of lubrication ,dirt and misalignment. Brinelling while stationary,from external vibrations is another.
Offshore Engineering&Design
RE: Ball Bearing Failure
it is hard to decide what came first: flaking and subsequent oxidation or oxidation, loss of heat transfer and subsequent flaking....
can you me more specific on operating conditions (speed, load, type of application, time in service) and lubricant type used?
RE: Ball Bearing Failure
RE: Ball Bearing Failure
Thank you very much for the comments and I am very sorry for a late reply as I was on a long holiday....
Tmoose,
Our bearing type is is 7220 MN MBR SU ,,,Single row angular contact light, 100mm bore, Angular contact low shoulder (both) 40 degree, Machined Bronze retainer , Flush ground, control clearance for duplex mount single package.
Pictures of the races and bearing separator/cage would be helpful.
Please find attached picture of raceways and cage.
Usually angular contact bearings exist in pairs, or even 3s and 4s.
This is with code 72..single row angular contact light that only can handle thrust at one direction..and not duplex.
Please Post pictures of the other bearings, and the housings and shaft as they were disassembled, and after being gently cleaned
How are the bearings >> supposed<< to be lubricated ?
It is lubricated automatically and filtered for any particle as the bearing is no accessible during operation as it a part in RGB.
In the first picture there is debris on the blue towel. If that came from the ball, I'm thinking the lubricant is charred or has turned to varnish.
The debris on the towel is from other part and not from the bearing.
And the ball looks quite dark, like things got pretty hot
It is not dark but due to the reflection. No sign of overheating and corrosion. However it has dark circumference..seemed like propagating from the centre as I mention earlier. When we did EDS analysis on this region we found silica, copper and aluminium, oxygen and carbon....Just I am figuring out from where these has come from...especially copper and aluminum...
What is the machine history?
The bearing is used for one year after replacing new RGB (reduction gear box). The indication after replacing this RGB was high vibration ...The bearing is at the output shaft used at the RGB...used in alternator.
RE: Ball Bearing Failure
The bearing manufacturer's name is still witheld.
What is operating rpm?
With a 100 mm bore I'm guessing relatively slow.
"Filtered" sounds like some kind of oil lube. Constant flow, air-oil, oil mist. I'd be checking for actual flow delivered to the bearing.
Are there any shut off valves or switches that could accidentally be off/closed while the machine was in operation? Some operators would have a hard time confessing to making such a mistake.
If any of the oil lines are exposed they might be vulnerable to damage that could limit flow.
I'm still not clear about The condition of the other bearing in the duplex pair. Did the pictured bearing suffer alone, or did both bearings die together?
Is the bearing shown in a position to be subjected to primary thrust loads ?
Cage/retainer wear is often a sign of inadequate lubrication.
BARDEN and SKF both list machined brass/bronze cage materials having max levels of Fe as 0.3% and Aluminum just .05% max.
Cage wear could conceivably liberate some iron or aluminum I guess.