Poor lubrication

[JeanMicheling]

Hello Folks,

Could someone tell me how to identify a poor lubrication with fft? I've been told that noise in acceleration is a good sign but I have no more details. I'm looking maybe for an articles that develop on this subject. Vibration litterature I have doesn't say nothing about that.

Thanks,

 

[sms]

seach on ultrasonic or acoustic emissions along with lubrication and you should get some hits. Also search on high frequency enveloping or peach vue.

-The future's so bright I gotta wear shades!

 

[GregLocock]

I've never heard of it to be honest, at least on plain bearings. By the time you picked something up the bearing would be damaged and about to fail.

Cheers

Greg Locock

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

 

[rob768]

In roller bearings, you may find an increase in random higher frequencies (noise) due to contat of asperities in the bearing races. In plain bearings, as Greg says, the moment you hear something, it is due to undesired contacts and then you are way too late.

 

[JeanMicheling]

Rob, you said there is an increase in noise with roller bearing, is it the same with ball bearings?

 

[rob768]

to my knowledge, yes, as ball bearing are just a type of roller bearings.

 

[JeanMicheling]

I used to make a vibration reading on each of my spindles after the run-up procedure. I always see noise around 240000 cpm. Could this noise be a cause of concern? If I understand, the only way to catch lubrication issue is to compare results? If the overall demodulation value increases from one spindle to another but with no signs of bearing defect frequencies, can we attribute that to lubrication?