Heres a scan I took out of the book...These are the coupling value tolerances, we scroll to the feet values when doing the actual moving of the machine, in mils, once we get to our goal, hopefully 000-.001 the scroll back to the coupling value, this puts the number well below the .5 & 2.0 for a 3600 rpm machine. I have done as well as 0.00 many times

quote:

Originally posted by Sam Pickens:
I think the V-180 is Fixture Laser. Re-painted for SKF and Vibralign or I could be wrong.

quote:

We went out and did a hot alignment. The tolerances for a 3600 rpm machine are .5 angular and 2.0 offset

Rod,

On the angular limits in the recommended tolerance, doesn't the .5/1" mean .0005 for every inch of coupling diameter? Do you have to enter the coupling actual diameter in the meter or do you enter the common "factor" of 10.
You coupling looks like maybe close to 10 inches, so the angular tolerance would be 10 times .0005 = .0015 maximum angular misalignment. Your last alignment was "well below" .0015, which is acceptable, huh?

I looked in the book on that, and could not find an explaination. All it says is tells you is the difference between coupling values and foot values.

I know when we align using this V180 system we normally always get below .002 mils which is good in anyone's book, and it is also the standard throughout the industry. As far as the coupling tolerance value goes, I'm not sure if it means diameter or coupling length. I'll have to look deeper into this.

I've always taken vibration readings right after an installation like this, and have been well down in the green, normally below .15 ips velocity on all points.

But on this motor not so...When I uncoupled it and ran it yesterday morning, I knew right away there was a motor problem, and my phase readings and spectrum support cocked bearings, for whatever reason, worn journals etc. The extra high axial readings was the giveaway for me on this...

We're still waiting on the motor shop to contact us back on this.

quote:

Originally posted by Ralph Stewart:

quote:

We went out and did a hot alignment. The tolerances for a 3600 rpm machine are .5 angular and 2.0 offset

Rod,

On the angular limits in the recommended tolerance, doesn't the .5/1" mean .0005 for every inch of coupling diameter? Do you have to enter the coupling actual diameter in the meter or do you enter the common "factor" of 10.
You coupling looks like maybe close to 10 inches, so the angular tolerance would be 10 times .0005 = .0015 maximum angular misalignment. Your last alignment was "well below" .0015, which is acceptable, huh?

I am in agreement with you on this, if the motor is worse uncoupled than it is coupled, Alignment appears to not be the issue.

Ralph is correct I believe. It is necessary to publish what you really mean; 0.5 of something is 'something' - having to assume is not all that good.

The Fixture laser unit is good and works well by all I know who use it. Unless something has changed it is for horizontal shafts only and limited on distance of span, but a very good unit.

AlignTolChart.doc (176 Kb, 13 downloads) Alignment tolerance chart

I already eliminated softfoot as well. And I did a close up inspection of the foundation, and support structure. Looks good. It was good before we pulled the motor out.

Every one of my velocity readings are like this one. Notice the dominant 2X, and the smaller 1X and 3X

I really don't know what else could cause the same vibration signatures in both radial and axial, but my wall chart shows it to be cocked bearings.

However, I will say something about the tolerance chart you posted; it is not very good or a reference to go by in my opinion and only good if you intend to leave something poor. Especially bad if you have hot data and knowns to work by.

We are driven by economics in a large part and I use tolerances that are close but alignment can be obtained to these tolerances in one-shot often utilizing proper procedures and methods.

Tell me something Sam.

Based on what I have posted here, and given the equipment we use, duly noted that it is probably not the best, and is getting older.

What would you recommend? Keeping in mind we do follow the equipment manufacter set-up and alignment instructions per their manual. I know of no other way to do precision alignments, short of upgrading the equipment. The span distance on this unit is 1 Meter, BTW

Isn't a mil a mil no matter who's equipment you use? Don't quite understand your last post. Or is it the overall tolerance you are questioning?

Just seems like simple math to me. If one gets his machine within .002 or less, it will automatically fall within the specified tolerance range, and be considered precise, not poor.

Thanks

Sorry for the confusion Rod; my fault. The V-180 is a good unit IMHO and should perform satisfactorily. I had just gotten confused from your post on anuglarity of 0.5 something or other as it wasn't defined.

The V-180 is manufactured by Fixture Laser and is very good; however, they do make an excellent unit that works well. They of course aren't the only one. They're a number of units but something to stress here ---- people do alignment. It's the person that performs alignment not the instrument. No one method fits all feet. Utilization of Long Spacer Coupling Method using dial indicators is generally better on long spacers such as cooling towers, etc... than lasers. Many instances dial indicators are better and faster than lasers. They all have their place and perfom satisfactorily in the hands of a qualified tech.

We generally go to various seminars, and classes during the year, and we're able to see new technology from the different vendors when they come.

I'm aware of several different brands, and I will be looking to upgrade here shortly. We saw the new Vibralign system last year at a show, everything works off of colors, red, yellow, green while your doing the alignment, and it even shows a mock up of the movable and stationary machine. It moves as you make the adjustments. Then if and when you do not touch it or make a move, a fingerprint will show up on the screen telling you your next move, and where to touch it. Pretty cool stuff there!

Okay I'm with ya...Getting ready to leave for the weekend. Big game tomorrow here in Baton Rouge. Florida Gators coming to town...

GEAUX TIGERS!

Rod,

Are you using a tach signal when measuring phase? If so check phase in axial around the motor shaft running solo, say every 45 deg. I realize that if phase is unstable it is hard to draw any conclusions, but do it anyway.

Having erratic phase means gross looseness in general. A standing out 2x may indicate a cocked bearing. So it might be a combination of both.

Is erratic phase present only on one end of the motor?

Also, having a ball bearings setup and seeing axial movement is weird. Did you observe axial motion with reference to the end bell or to any other point?

I also recommend taking high resolution data with Fmax=15xRPM

David

Thats the best conclusion I came to was a cocked bearing due to housing wear perhaps. I've posted all my readings and info which points to that. I took my phase readings with a tripod and vibration strobe at 4 locations axially, and 4 radially...

Should get the motor shop out here to look this week.It would be unusual for the motor repair people to not catch something like this, hmmm thats what bugs me.

quote:

Originally posted by David_G:
Rod,

Are you using a tach signal when measuring phase? If so check phase in axial around the motor shaft running solo, say every 45 deg. I realize that if phase is unstable it is hard to draw any conclusions, but do it anyway.

Having erratic phase means gross looseness in general. A standing out 2x may indicate a cocked bearing. So it might be a combination of both.

Is erratic phase present only on one end of the motor?

Also, having a ball bearings setup and seeing axial movement is weird. Did you observe axial motion with reference to the end bell or to any other point?

I also recommend taking high resolution data with Fmax=15xRPM

David

hi rod
so what happened next?
does this motor put back to service?
is the sympton of high axial rdngs and an erratic phase, and 2x in your spectrum does confirm the bearings are cocked? or loose housing.
thanks
ian

ian

Talked to the motor shop this morning. We're sending it back to the shop...I double checked the axial again, and had increased readings from .45 to .98 on both bearings.

I also had my hand on it when we killed the power to it a while ago, and noticed the vibration stopped right away when we killed it.

Could be any number of things.

I'll be anxious to see what they found on this one!

I see your in Manila...My wife is from Cebu City. We were just home last year, went to Boracay, and Bohol.!

Take Care,

quote:

Originally posted by ianski:
hi rod
so what happened next?
does this motor put back to service?
is the sympton of high axial rdngs and an erratic phase, and 2x in your spectrum does confirm the bearings are cocked? or loose housing.
thanks
ian

ian

Now as think of it, with standing out high magnitude 2x and erratic phase it could be a resonance in axial. Amplitude dropped sharply once RPM slowed slightly down. Check for mounted resonance if it is not too late.

David

This blower & motor has a 15 year history of running well in the green range. In fact it was one of my better ones.

The vibration readings on the blower itself after reinstalling the motor was where it was before we pulled the motor. Great shape! It's just the motor. It has no soft foot, I did that check with the laser, and rechecked it with a dial indicator. All ok...

Most of the test we've been running has been with blower uncoupled, so it all seems to be within the motor. Anyway, it's already out and sitting in the shop for pick-up again.

Soon as I get word from the motor shop, I'll pass on the findings to ya'll. I know it has big time axial vibration in all velocity readings, and some as well in ACC.

Has anyone here had a similar experience with an overhauled 350 hp blower motor?

I've just learned that the 350hp blower we had repaired did indeed have bearing problems. This was after it had been overhauled, remember, when I first posted this?

Very unusual but it did happen. So that was a good find on this motor. Once for the original bearing problem, and again after I reinstalled it, after it returned from the motor shop, and noticed the vibrations.

It confirmed all my spectrums, and also those very high axial readings I was getting. Cocked bearings.

Just wanted to pass that on to all who assisted me in this...

Thanks,

Rod,

It is always nice when the poster follows up. Thanks.

A cocked bearing was one of the suspects to begin with but erratic phase was and still is a confusing factor although more details on installation errors if available could shed some light on this as well.

David