Hi Svein,

Looking at the sidebands, I can't confidently say that there's alot of consistent info to provide a clue on the problem.
I tend to believe the 3.1X is a localized excitation...could very well be due to the way the cooling fan is arranged/installed.
Motor NDE Axial....Where did you mount(Magnet or Stud) the sensor? Was it on the Fan Housing/Guard?
Thanks.

Rajan

Its a stud mounting. With quick connects.

Nahh..was just curious about the sideband spacing.Thought it could make some sense.

Hi Svein,

Don't wanna let this fall thru the cracks! Any developments at all thus far with the 3.1XRPM issue??
I remember Electricpete mentioned earlier that this could be bearing fault and I remember reading somewhere that this was the case. Did you get a chance to check on this?

Cheers...Rajan

Situation as of now:

We have 3 motors which have the 3,1x peak, two of them which fall below the limits set in ISO.
The 3'rd one is above 4 mm/s rms, with most of the energy in the 3,1x peak.
We have send a request for removal and dismantlig of this one, so we can try to locate the source of the vibration.
In case of some failure within the motor, we can probably route it to the other ones anyway, and do a desent follow-up on them.
We suspect a bearing damage, but of course cannot be certain.
I cannot see impacts whatsoever in the waveform, so im still not certain about this.
Probably there could be some other forces affecting the bearing house, so that we get a BPFO frequence.Stuck bearing,deformed housing,loose fit...dont know.

Anyway, will give an update as soon as i know anything more.

Just an update:

Got the results some days ago from the workshop that overhauled the motor.
They couldn find any obvious damage to the bearing, altought they did not split the bearing.Bad communication.
We are currently awaiting the motor back to site, and will have it reinstalled and re-run.
Hopefully vibration is gone, but unfortunatly that still leaves us in the blue as the bearing never was splitted and checked inside.

Im still reconsidering the problem. As you can see in another post here.

Svien,

My place of employment is implamenting a new CBM program. I have been collecting Machine data since last April and our CBM staff has just started routes in the last couple of months.
We are all rookies here and new to the vibration game. We are using SKF MA and Aptitude software which helps us alot with making calls on problems.
We are finding that trending is a tool that helps us. We have a lot of rebuilt motors and pumps and they seem to be tricky to diagnose.

Cheers

Well hello there ddane.

Welcome abord the rookie boat then. Still struggling myself, but the trende of knowledge at least have a peak going upwards, which is a good thing.
The past months i have been doing nothing else then measure, trying to analyse and reading my training books and notes.
Still there is a long way to go.
But im getting there...i hope

An update on the issue:

Motor was sent to overhaul.
Bearings changed and returned.

After retesting found no sign of the high 3,1x peak.
Unfortunatly, they put the bearing in the trash, so we never got to see it.
But case closed, and most likely it was the bearing the had a some sort og defect.

Svein
With regards to your question about 3x, Can anyone explain the following: If you take a thin metal plate and drill it with a normal twist drill, invariably you will end up with a triangular hole, is this is a result of excessive looseness or annular rub? Could this be why we see 3x? Any comments?
Havagoodone