Goodday all,

Can anyone please comment on what could have cause the following damage bearing ? The technician had complaint of abnormal sound while running, thus we took the bearing out for inspection.

We had a doubt whether it was stationary vibration or electrical fluting (initial condition) .?

The bearing designation FAG 22320 E1 C3

This is what we saw ;-

Rgds,
Amberdog82

It sort of looks like electrical fluting, but a very severe case. The "rub board" pattern appears to be stacking on top of each other, sort of like it has been running a fairly long time and building up electrrical "bar marks" over and over.

Does the surface have the rub-board feel when you feel of the surface. Hard to tell for sure from the picture.

From the other post by AMBER this is the 1st stage planet spindle bearing. In a planetary arrangement these bearings are the most difficult to lubricate since the planet carrier rotates about an axis different that the planet spindle.

What type of machine?

John from PA

quote:

Bearings.
150 NU 2230 ECM
151 22326 CC/W33
550 24034 CC/W33
551 24036 CC/C3 W33
255 SL 1818/600
256 SL 1818/670
248 SL183044 C3
348 22326 CC/C3 W33

quote:

The bearing designation FAG 22320 E1 C3

quote:

From the other post by AMBER this is the 1st stage planet spindle bearing. In a planetary arrangement these bearings are the most difficult to lubricate since the planet carrier rotates about an axis different that the planet spindle.

What type of machine?

John from PA

Hmmm! Amberdog82 must have made a typo between the two posts.

Looking at the spald on the right side of the bearing race in the center, it appears to be roller length "bars" along with the 3 individual spalds. Might not mean much. Just a note.

Goodday sir,

The planetary gearbox in one of the twin drives of a Polycom - Polysius Roller Press for clinker pre-grinding in the Cement Milling Process.

First off, I'm no expert.

It's difficult to tell from the pictures, but it looks like the marks are heavier on the left side of each race section?

This might be an indication of excessive side load on the bearing.

The markings do not look like they are electric current EDM. Possible cause is excessive dynamic loading and there may be incorrect or insufficient lubrication contributing to the problem.

Walt

My guess would be axial vibration while stationary (false brinneling).

If it is false brinneling, you should see families of marks that have similar severity spaced apart at the same distance as the rollers. (do you see that?)

In addition to the axial lines, it looks like you have some particle denting or pock marks - particularly along the center of the right race.

What did the outer ring and rollers look like?

Just some thoughts on brinneling... Amber, you can differentiate between true and false brinneling by looking at the surface finish of the mark. A true brinneling "dent" will generally retain the original machining characteristics (grind lines) while a false brinneling mark will not.

In case of electrical ptting, ther will be bright line marks, at a pitch equal to ball/roller centre.

DKSONI
INDIA

quote:

at a pitch equal to ball/roller centre.

I have always associated that type of spacing with false brinneling, not with electrical pitting.

It is really hard to tell for sure from the picture what is going on but there seem to be several roller length marks (some are even longer than others) randomly spaced on the surface. Like maybe it is sitting still and being vibrate while in the static position, as noted by others.

I am in agreement that electrical flutting usually looks differently than this does but if the electrical current has been going on for many days or months could it get to the point of "lapping" over previous marks? Not that I have ever seen this happen, just wondering if the elect marks are always in the same place no matter how long it runs while this is happening?

If it is static marks from vibration while it was down, would the other bearing also have axial slide marks on it also?

I have always seen axial groove marks associated with false brinneling , both in the literature and in our plant (confirmed to be false brinneling based on the spacing and also sometimes by measurements of brg housing vibration with machine secured). I have never seen a circumferential groove from false brinneling. (has anyone?)

I don't know the exact reason why that is.

One possibility: In response to axial vibration, the roller is more likely to slide than to roll. For radial vibration, the roller can roll. This effect is also present when the machine is running, but then there is much better lubrication available when running due to the rolling which is occuring.

The above explanation makes most sense to me for rollers (like spherical roller pictures here... spherical roller is not spherical by the way) since the roller cannot possibly roll axially, but the explanation doesn't make as much sense for ball bearings which can roll axially. Surprisingly, I also see axial marks on ball bearings. So why does it happen on a ball bearing? That I don't know. One difference between axial rolling and circumferential rolling (in a deep groove vall bearing) is that the radius of curvature for rolling in the radial/circumferential direction is much larger than for rolling in the axial direction... don't know if that makes a difference. Perhaps there is something else to do with the fact that the radial vibration has no torsional component?

This message has been edited. Last edited by: electricpete,

Here are a few slides to consider. It looks like electrical discharge (EDM). However, in this type of bearing, it is possible that there is some level of false brinneling if there is a fair amount of local vibration.

With the discussion of a lack of lubrication, I have also included a few slides with faults related to poor lubrication.

Howard

A_few_bearing_issues_from_Lube_Presentation.ppt (256 Kb, 49 downloads)

Electrical discharge and false brinneling can look very similar. It certainly can be either one. In my opinion, we really can't see enough to tell the difference from this one picture (because for one thing we don't know what your rolling element spacing is). But if it is false brinneling, the pattern can be easily seen upon very close examination with the bearings in your hands. Every time the machine is exposed to vibration while shut down, you get a set of marks which are separated by rolling element spacing. If it is shut down for a long period one time and a short period the next, you end up with one set of deep marks and one set of light marks. When you look at the end result (your removed bearing), marks separated by ball spacing should have similar severity. If you see no pattern resembling rolling element spacing, then electrical discharge becomes the prime suspect.

Slide 1 shows a bearing pulled from our plant due to vibration. There is one deep set of marks spaced exactly at ball spacing from each other. Than several other series other lighter set of marks spaced at ball spacing from each other. The balls/cage are held next to the race so you can see what the ball spacing is.

Slide 2 is an excerpt from NTN publication 3017/E dated 03/96 ("Care and Maintenance of Bearings"). Both those photos have an appearance not tremendously different from yours. On the left is a cylindrical roller bearing with one absolutely uniform series of marks (I assume at roller spacing). This would have had to have been caused by a single occurence of vibration while secured (multiple occurrence would cause a more complex pattern). On the right is a deep groove ball bearing with more complex spacing ... presumably would come from many many instances of being exposed to vibration while shut down (with the balls in different positions each time).

NTN_FalseBrinneling.ppt (1,374 Kb, 36 downloads)

It could also be both.

In the enlargement that Ralph posted I see one lighter shaded line that appears to have the "scooped out" look of electrical discharge and others that have the hammered appearance of brinnelling.

quote:

quote:
at a pitch equal to ball/roller centre.

I agree with Pet. In fact I have never seen
it when it was equal.

Barry,

Me, too.

I think you might see roller spacing in electrical pitting if you have a welder connected through a stationary motor, though. I have heard about it, but never seen it, so I'm just guessing about the spacing.

Here is more information on brinneling, fluting...

SKF_Bearing_Analysis_Photos.pdf (450 Kb, 43 downloads)