Kishore kumar posted:

Dear Messrs,

does it means manufacturing / assembly error .

if  the rolling element missing ,bearing could not able to hold the load from the machine and it leas to immediate fail .

I would think that is somewhat dependent on the load.  I would also, again subject to load as compared to rating, not suspect an "immediate fail".

As to the OP's original question "Is it possible to detect that a bearing is missing a rolling element by vibrational analysis?", I have no direct experience that would enable me to say "yes" or "no" but I do think that with proper instrumentation and tools, it would be detectable.

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Sorry Barry, no data to provide. The OP only asked if it is possible, but he/she did not provide the circumstances or situation or need to know. Generally in a plant environment, when a ball pops out of the cage/retainer there is plenty of evidence of a bearing fault/failure detectable by vibrations, sound, or ultrasound.

Several years ago I developed a precision ball bearing test method for measuring Contact Angle as a quality control of manufactured bearing dimensions. The system could detect a missing ball, but I don't know if the OEM actually found one or tested the capability to do so.

Walt

 Normal answer for you Walt an I am surprised you did not suggest a bump test. I saw with my own eyes and had data to back up what I posted were as you had nothing to back up what you posted. Unlike you I gave him a real answer and as John stated it would or could shorten the bearing life.  I am away from home for an extended period of time but will be glad to post a photo of said bearing at a later date. 

From your photos I would say it could well be possible that the lack of one element wouldn't show as some failure detected. The question is where is the roller? Is it missing from the new bearing or was it damaged during operation? This could be crucial for correct answer. 

Marco,

Another view of your photo clearly shows damaged cage/retainer. Other views showed roller surface damage. This bearing condition should have been detected by vibration measurements. If it was not, then possibly damage occurred in the interval between vibration surveys. If it was fault was present, then the vibration monitoring and analysis techniques should be improved. 

Back to your original OP question; bearing fault diagnostics does not normally detect a missing rolling element. The fault detection process is focused on excessive dynamic loads (like unbalance and misalignment), lubrication, and surface defects (inner and outer rings/races, cage/retainer, and rolling elements). For the example you provided, the bearing has surface faults and cage/retainer failure. I am guessing that roller fell out upon bearing removal and not during machine operation.

Walt

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If I understand correctly you didn't even find the rolling element? In this case you should notice obvious metal contamination in your grease because the element probably fell apart as completely damaged. I suspect you should also see some damage on the rings and that should be noticed with measurements.  

Becar posted:

If I understand correctly you didn't even find the rolling element? In this case you should notice obvious metal contamination in your grease because the element probably fell apart as completely damaged. I suspect you should also see some damage on the rings and that should be noticed with measurements.  

I would really doubt that one rolling element would deteriorate where one would “...notice obvious metal contamination in your grease because the element probably fell apart as completely damaged”.  The OP can correct me if I’m wrong, but it seems there is little if any apparent damage on the other rollers.

Marco,

I do not see how the roller (assuming it is intact) can exit the bearing, since the inner ring/race has a lip to keep it in place axially. I can see how it can come out when outer ring/race is rotated/twisted (your 1st photo), since the cage that normally would retain it is deformed. If you zoom in on the photos, the other rollers have a very rough surface. Your story about the bearing is quite unusual!

Walt

Marco,

With the bearing rings/races aligned as they would be in the machine, can you actually remove the roller that you (or others) say came out during machine operation? I don't believe it can be removed with bearing rings aligned, but I will buy you a beer if it can!

If a bearing fault was not detected by vibration analysis, then why was the bearing removed? There is clear evidence that faults are present, but it may have stayed in service longer depending upon shaft speed, load, lubrication or other issues. 

Walt

Walt Strong posted:

From the photo:

NSK 22220CAMKE4G351 1 Japan 1506

Walt

Nothing that I see unusual about that bearing so unless there is significant cage wear or some other form of damage, like Walt says, it is essentially impossible for the roller to come out when the inner and outer race are properly aligned.

The catalog is at https://www.nskamericas.com/co...brochure%20Final.pdf

There is one peculiarity, but likely just a typo from the catalog.  The particular bearing as described in the catalog at the link is not available with a brass cage (see last line in image below) yet the "CAM" designation is for a one piece machined brass cage and this is certainly Capturesupported by the photographs.

Just for FYI, the various designations are decoded as 

NSK 22220CAMKE4G351

Cage options CAM = one piece machined brass cage

Bore Type K = 1:12 tapered bore

Lubrication Features E4 = Groove and holes in outer ring

G351 = unknown

 

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