Srs. Forum:
Good afternoon, in the company in which I work failed the two bearings of the electric motor for lack of grease; attached acceleration and acceleration envelope spectra taken on various dates; as reported by the monitoring staff indicate that there is no bearing anomaly in the spectra; however I am observing that these spectra are indicating that there are lubrication problems in the bearings.

I will appreciate your technical comments on this.

Regards

Attachments

Original Post

Dear Marco, 

The word failure in Ball bearings depends of severity (amplitude)  and kind or frequencies appeared in spectrum, the spectrum attached by you still no show frequency con dangerous amplitude to say ¨Failure¨, but 3rd stage of bearing failure is in process. 

Look the next severity chart of IRD Mechanalysis (pag. 5) and select the frequency of bearing appear in spectrum after you can determine the severity of damage. 

the OverAll vibration depends of Fmax that you are selected for take data, also default  bandwidth  of you data collector take filtered data for bearing condition (HFD, PeakView, Demodulation) 

I hope I help you.. 

 

 

Attachments

Mr. Ramón:

Good morning, thanks for your reply; What I have tried to say, is that the bearings failed because they had no grease (attached photographs of the two bearings of the electric motor) and one of the bearings came out with the cage broken and the other bearing came out hardened (could not be rotated manually ), my query went in the following direction:

Do the spectra displayed both acceleration and acceleration envelope indicate lubrication problems ?.

I will appreciate your technical comments.

Best regards.

Attachments

Mr. Marco

Im looking with more details the vibration reading date.. can you say us the failure date. 

In september 2018 spectrum , we can observe random peaks (like noise)   from 1.5kHz to 5 KHz, likely due to lubrication problems. 

the last reading was september 2018. 

ramonruiz posted:

Mr. Marco

Im looking with more details the vibration reading date.. can you say us the failure date. 

In september 2018 spectrum , we can observe random peaks (like noise)   from 1.5kHz to 5 KHz, likely due to lubrication problems. 

the last reading was september 2018. 

Mr. Ramón:

The bearings failed the 24/01/19 and the last vibration data was the 26/12/18. 

Attached file with the different vibration monitoring of different dates.

Attachments

HI Marco, 

we need more to do more deep analysis. 

1.- please more details of motor.

2.- type of load , is it constant or variable?, belt t  or coupling transmission, for example.  

3.- velocity spectrum and waveform the last reading

4.- accelerometer data sheet

5.- if it is possible, photo of motor

6.- Environmental condition (temperature, dust, etc).

7.- The relubrication is possible?

8.- Historical temperature of bearings (trend).

ramonruiz posted:

HI Marco, 

we need more to do more deep analysis. 

1.- please more details of motor.

2.- type of load , is it constant or variable?, belt t  or coupling transmission, for example.  

3.- velocity spectrum and waveform the last reading

4.- accelerometer data sheet

5.- if it is possible, photo of motor

6.- Environmental condition (temperature, dust, etc).

7.- The relubrication is possible?

8.- Historical temperature of bearings (trend).

Mr. Ramon:

Attached as requested.

Regards

Attachments

Dear Marco

as we can see, acceleration spectrum and envelope spectrum not represent real condition of bearing, also it means and I can suppose the radial direction load is very low with respect to axial load.

please can you send Velocity spectrum and waveform..

also, please can you send axial vibration reading.

is the axial load very high with respect to radial load in bearing?

kind of coupling?

the load is constant?

can you send more detail of the equipment coupled (driven).

best regards.

 

 

 

 

ramonruiz posted:

Dear Marco

as we can see, acceleration spectrum and envelope spectrum not represent real condition of bearing, also it means and I can suppose the radial direction load is very low with respect to axial load.

please can you send Velocity spectrum and waveform..

also, please can you send axial vibration reading.

is the axial load very high with respect to radial load in bearing?

kind of coupling?

the load is constant?

can you send more detail of the equipment coupled (driven).

best regards.

 

 

 

 

Mr. Ramón:

Attached Waveform Time and Spectrum Speed.

Best regards.

Attachments

Dear Marco,
As we can see, vibration analysis didn't show enough evidence of the state of deterioration of the bearings to anticipate the failure, therefore, I propose the next step, make an analysis of bearing failure, then rule out manufacturing defects, load evaluation axial since this type of bearings do not support large axial loads, only a percentage of the radial load, also, investigate why not was lubricated at first time, etc.
Prior conclusions to failure analysis and questions:
bearing 1:
the bearing side 1 failed due to lack of lubrication.
the acceleration, waveform and  spectrum not showed indications of this lack of lubrication (all amplitude  readings below acceptable levels and no dangerous levels using ISO 10816)
Lack of lubrication caused the cage to fail in bearing 1.
The radial load in bearing 1 is low, so there is no evidence of large impacts in acceleration or in the spectrum, only the waveform represents low amplitude of looseness  and impacts.
evaluate type of assembly and brand of bearing.
create system of re-lubrication.

bearing 2:
I recommend opening the bearing, to evaluate the internal damages.
Bearing brand?
create system of re-lubrication.

best regards.

RRR

gE should be measured in Peak for starters in the spectra shown its displayed in RMS....the setup shown is wrong!!!! you always measure gE in Peak or peak to peak with the average set to 1.

You have a telltale haystack in the acceleration at the 'golden' 180,000 cpm area of the spectrum( for 50 Hz electrical supply machinery) which points to a bearing issue, most likely electrical related shaft current( In my experience with SKF microlog) Lubrication issue would show raised even noise floor in gE but with the RMS setup, this is hard to make out. Go back and set your instrument up correctly (gE in Peak) Have you had them examine the bearings for signs of wash boarding pattern, discoloured thickened grease? frosting on the rolling elements?

 

 

 

 

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