Vibration / Noise Monitoring System

[OnOff]

An odd one but here goes..............I have a piece of equipment on site that is in effect a scissor lift, so a collection of metal box sections with pivot points where they join. It goes up/down via 4 hydraulic rams. There are some 30 pivot points on the system. These are a a mix of phosphor bronze buses and plain spherical self aligning bearings. Now then, I think that one or more pivot point is noisy but for the life of me can't find which one. I've employed a hydraulic specialist and engaged a bearing company plus other people have observed it. Some have said don't worry about it, others that it's "probably" ok to use.

I've been over it with a stethoscope - no joy. I've even thought about building an electronic one that uses a piezo sensor as a "mic". The noise it makes is intermittent too and echoes around all the hollow box sections. A mate reckons that a monitoring system exits but doesn't know where he saw it / if he dreamt it. IF such a system exits I would like:

- Magnetic (as in to attach it to the steel structure) microphones that can be placed at each pivot - wireless sensors would be good.

- Results displayed on a laptop

- Multi channel on screen display

- Recording in real time 

I'd like to be able to then run the machine and look at any noise "peaks" picked up by that particular sensor attached to that particular joint.

Any pointers would be appreciated of who does such kit. As a youngster I used to build simple op-amp mixing decks with 4-channels (along with drum synths etc). I wonder if that type of thing is now available in some readily available form on a laptop. Then it's these stick on mics I need!

Cheers

 

[Technician]

Only a suggestion;  if you call in a conditioning

monitoring specialist and he can put a sensor

on the suspect bearing and measure the noise

by reading the peak velocity of the bearing as

it lifts. 

I have done some work with these in the past and

peak velocity reads (usually) indicated bearings 

that were noisy/worn/possibly about to fail.

I know there may be a cost but I think he could

find it in a moment.  From my memory of these,

there are a lot of bearings on them. A dozen

plus?

Yes, I was doing something like you when I was

a lad.  Taking valves down the road to be put

on test.

 

[OnOff]

Only a suggestion;  if you call in a conditioning

monitoring specialist and he can put a sensor

on the suspect bearing and measure the noise

by reading the peak velocity of the bearing as

it lifts. 

I have done some work with these in the past and

peak velocity reads (usually) indicated bearings 

that were noisy/worn/possibly about to fail.

I know there may be a cost but I think he could

find it in a moment.  From my memory of these,

there are a lot of bearings on them. A dozen

plus?

Yes, I was doing something like you when I was

a lad.  Taking valves down the road to be put

on test.

Cheers. Any companies that you can suggest for this?

 

[OnOff]

Where abouts are you in the country ?

Job's in London, next to a tube station handily. I'm speaking to the Oceaneering's inspection division and the bearing company Shaeffler at the moment on this.

 

[OnOff]

Check your PM's - choice of 2 that will do on site condition/vibration analysis

Cheers. Yep, used them in the past but not for this. Will give them a ring.

EDIT: Scoobed!

 

[Technician]

Onoff; post a bit of feedback after he has done the

business;  would like to read what he said.

 

[OnOff]

Onoff; post a bit of feedback after he has done the

business;  would like to read what he said.

Will do though though it is commercially sensitive so will have to pick my words!

 

[Sidewinder]

I'm guessing the bearings are low speed rotation?

If so you will struggle with traditional VA, in velocity & acceleration, you really need to be looking at displacement analysis.

Would be very interested to know as much as possible on this as I was responsible for VA at a previous employer.

Not when I was at Schaeffler though!

Canoe,

Be interested to know who you suggested, I may know the guys!

 

[Sidewinder]

Don't know the guys in London, only Camp Hill & a few of the Directors...

Now they have closed Bridgend branch.

 

[OnOff]

Spoke to Dowding's this morning the guy I spoke to reckoned what they could offer WOULDN'T suit my requirements - seems he used to work for a subbie to Maclaren doing multi point analysis on racing engines so seems pretty clued up. Reckons my idea of the multi channel acoustic thing was the way to go. Yes, VERY, VERY slow speed - never measured but way less than even 1RPM! The whole machine weighs 56 tonnes in total and raises through about 15m.

Shaeffler came back with a name of a company too (escapes me for the moment unless I log onto work's server).

Pretty sure after more work today that I have a phosphor bronze bush that has seized / picked up on a large diameter shaft (180mm). The bush, 200mm dia / 10mm thick is rotating in it's supposed interference fit machined bore. Having some special grub screws made up to try and "lock" the bush in place.

Will advise how I get on.

 

[OnOff]

Talking to this chap:

http://www.iantaylorpcm.com/

Who consults for both Shaeffler and Mistras:

http://www.mistrasgroup.com/services/advancedndt/acousticemission/

Been given a budget price of £2.5K for a day's investigation / report by Mistras

Seems my mythical, multi acoustic, magnetic sensor system is bog standard kit to them!

 

[Sidewinder]

TBH, I'd be going for eddy current or displacement with the shaft velocities you have if I understand correctly.

I can put you in touch with someone, but they will be circa £2 - £3k per day and they are based in the North of England.

I do know someone nearer, but they are sensor specialists, they turn over multi £M per annum I I know the MD, last time I was in his neck of the woods he bought me dinner & beer!.  So they are hardware rather than measurement guys, but, they may have guys that they sub out to.

Please PM if you are interested.

I don't know the VA guys as Schaeffler as the department was started up after I left.

 

[OnOff]

A little update on this. Tomorrow I have Mistras coming to site (£2.5K for the day)..................to do Acoustic Emission testing. 

 

[Sidewinder]

Sorry mate not convinced AE is the way forward for you.

I had one of the industry leaders in AE into our place several years ago,  to do some stuff in the workshop as an exploratory visit to see if his kit was any good to us, and it diagnosed faulty motor bearings when the motor was stationary and just holding position under command!