Hi all,
two set using to crush bean,one using that vibration value is 2.5mm/s for 6 month ,another rest.
now hammers piece of the using crusher wear,the rotor is unblance.so turn off it.turn on another set.
we collcet the vibration data.the Demo value is 22.464g, vibration value is 6.716mm/s. after 5 days,we turned off to rapair it .
Attachments are picture of the bearing outrace and vibration data.
somebody could explain this.

bearing_outrace.jpg (29 KB, 145 downloads) bearing outrace

just attach the vibration data

Demod_Spec.jpg (136 KB, 91 downloads)

Velocity Spectrum

Vel_Spec_1600_Hz.jpg (208 KB, 77 downloads)

The damage shown in the picture appears to be false brinelling, similar to what is sometimes more commonly called "transportation damage". This is where the rollers vibrate in one spot and brinell the ring surface while the bearing is not rotating. The dark spots in the picture are within the brinell spots and appear to be from fretting, which usually results in the formation of brown oxide.

I know for automotive rings, this type of damage cannot exceed one micron below the raceway surface. I'm not sure what the allowable damage is for this particular bearing.

I'm assuming this appllication is lubed with grease. This brinelling condition can sometimes be alleviated by a different choice of grease - and not necessarily a heavier grease. In fact, a lighter grease is often more desirable in micromotion application, as this grease would be more able to reflow under the roller after it is pushed aside during micromotion.

Kluberplex BEM 34-132 is such a grease made for micromotion applications. Check with your bearing supplier for the best grease to use in your application.

Hi Kestas

quote:

I'm not sure what the allowable damage is for this particular bearing.

you mean,in this case ,although the noise is terrible,the bearing can aslo work.we need to monitor it seriously,then decide when to repair it.

quote:

Kluberplex BEM 34-132

i will check the grease.Is there other methods to avoids false brinelling.
could you give me some paper or reference about "false brinelling".
Thanks.

Unfortunately, my expertise stops after forensic examination. If your bearing is making noise, I believe that is enough to condemn the bearing. I can't comment on measured vibration levels.

I don't have information on false brinelling at my fingertips. I think the concept of false brinelling is rather simple... When components in contact with each other vibrate in the static condition, the material becomes dented. During vibration, the high spots get flattened, there is micro-cold-working at the surface. fine particles of the material are sloughed off, immediately turning into iron oxide, which appears as brown material inside the marks.

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

i see,thank you!

Leisure,
I hope it isn't too late to rescue this problem. The outer race and data do NOT indicate brinneling, but in fact it is EDM or fluting. This is caused by current arcs through the bearing. Is this piece of machiner on a variable frequency drive? Either way, you need to isolate the stray currents that are grounding themselves in this bearing.
Regards,
Ron Brook

Good points.

For me it's tough to tell from the pictures which one: EDM or false brinnelling.

I suggest to compare the rolling element spacing to the pattern. If you have more severe mark recurring at a spacing corresponding to rolling element spacing, then it is false brinneling. If more uniform with no pattern related to rolling element spacing, then possibly fluting.

I've seen this damage before and it is not fluting from electrical damage. This type of damage is typical for an application where the bearing sits stationary for a long while in a vibrating environment. The vibration produces false brinelling and the characteristic dark fretting products on the raceway. Then the motor is used, stopped, and the rollers now vibrate in another random position. After a while, a pattern of overlapping false brinell marks are produced on the surface.

In my personal opinion, you are probably right. But there are other opinions. And none of us holds the bearing in his hand. So once again by checking the spacing of the rolling elements to the marks he will know for sure. And perhaps he will have learned the distinguishing feature for diagnosing false brinneling (spacing of race marks the same as the roller spacinga) so he can diagnose himself next time.

EDM was also my opinion when I first looked at the picture - a typical washboard pattern. Also, false brinelling is normally black due to oxidation, which is mostly not the case here. However little of false brinelling is also present. So, it is rather a combination of two, but EDM is dominant.

quote:

... Also, false brinelling is normally black due to oxidation...

Not always. The damage needs to be advanced.

In addition to having the bearing "in hand" or at least a better picture, SEM examination is an excellent way to referee any electrical damage.

quote:

ue to

guys,

another bearing may be caused by current arcs through it ,see Attach

Electric_damage.jpg (83 KB, 49 downloads)

aslo,see roller of bearing。

can we detect EDM from vibration data? Does the EDM have features that we can distinguish other problem such as bearing porblem、loose etc. we can aviod emergency stop.

Electric_damage-2.jpg (76 KB, 39 downloads)

The damage shown in these two pictures is textbook electrical damage.

Hello Leisure,

To answer your most recent question and not the OP try a search of the forum using the keyword "fluting" rather than EDM

See this link for a recent discussion

http://maintenanceforums.com/e...=887108483#887108483

Zoll,

thanks a lot ,谢谢！

leisure,
You can't predict EDM from vibration readings. Vibration readings can tell you when it's already too late. A Rogowski Coil (air core current sensor) is required to measure the current circulating in the motor bearings. Please check for the ABB tech paper on testing for EDM and you will have all you need to correct this problem.

quote:

ir core current senso

Ron Brook,

Thank you, i will try