Greetings Mr. AYMAN GAMAL,

If you have taken on Motor DE/NDE bearings and Axial vibration high, you can expect rotor Shaft bend. Normally in over hung fans and blowers, Horizontal motors when bearings overheated shaft bend occurs and Axial vibration will be more than radial vibration.

Please send the spectrum with motor 1x identified to see the pattern.

regards

chary

 

The truth is high axial vibration on electric motor is really not common;

In this case based on the data u have provided, the high axial vibration is both on the drive end and non drive end; it certainly means the problem maybe inherent in the motor or maybe caused by high axial load from the screen...What I would advice you to do is run the motor on solo first, to eliminate any axial load condition from screen, if it persists on solo run, den you have to check the run out of the shaft, basically you should have a maximum of 1 thou, although u can check run-out tolerance on the service manual, if it's above the tolerance it's obvious the shaft is bent...but if it's okay, you will be left with checking the condition of the thrust bearings, or even the bearings if they are cocked, motors used for screens are fitted with bearings with high axial capacity...

On the other case if the axial vibration vanish on solo run, then you will have to inspect the condition of the coupling, screen structure and load condition...least I forgot, how about the amperage on the motor is it normal?

I have seen a lot of similar cases in our steel industry.

High 1x or 2x axial vibrations can have many reasons. Follow the following steps 1 by 1.

1. Run motor in solo condition. If high axial vibration is still there, bearing should be out of clearance that makes it slide axially.

2. If on solo, axial vibration is dropped, there is a strong indication of axial misalignment.

(in solo condition, for perfect machine your vibration readings at all locations should be closed to 0).

3. If all two above steps are done and high axial vibration is still there, go for phase analysis and confirm bent shaft.

 

 

Thank you.

 

 

Dear Ayman, 

check vibration behavior at sereval representative points of structure, and you can see the biggest vibration point in axial direcction, because you are taking reading in axial point of motor, but remenber that the motor is held down to the structure and if the structure move.

best regards

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