Does anyone know where I can find (and buy) the publication describing the method of 2-plane balancing without phase (an extension of the 4-run balancing method)?

Thank you all in advance

IFToMM September 2006 proceedings paper 182 has the multi-plane solution. If you want to buy a copy of the Proceedings (each CD-ROM EUR 40,- excluding shipping costs) please contact

Renate Mühlberger, Tel: +43-1-58801-30301,
E-mail: renate.muehlberger@tuwien.ac.at.
Retrieved from "http://iftomm-rotordynamics2006.mdmt.tuwien.ac.at/index.php/Conference_Proceedings"

This message has been edited. Last edited by: William_C._Foiles,

Someone a while back posted a website www.vibronurse.com and I got their no-phase program from the site.

The vibronurse program looks like a single plane program, and it seems to require weights exactly at the 120 degree points.

Basically a compass and paper will do. Scribe a circle equal to a preset scale (1" = 1 mil, etc.). Scribe the original run and break the circle into 120 degree segments and then attach your 100 gram wgt at 0 and scribe your results from that point. Remove the wgt and place @120 degrees and scribe that magnitude fro the 120 axis. Likewise @240 degrees and where the circles meet will show phase angle and amplitude. Or someone can correct me!

Bill,

The vibronurse program take care of real positions of the weights put on the rotor in the calculations to find the right resolution weight and angle.

If you write "12" for example for the number of blades, of course the positions of the weights will be at 0, 120 and 240 degrees but if the number of blades is "7", you have to put the weights at 0, 102.8 and 257.1 degrees or blade number 1, 3 and 6 as shown on the graph.

I use this program from time to time and it works!

Interesting, but this still seems to require the weights to have a spacing set to an integral number of blades.

It still looks like the program chooses the angles for you, instead of letting you choose the locations. Plain graph paper doesn't limit you.

That doesn't disturb me at all that a program chooses for me. The advantage of using it is to save time. I know the basic method to do it anyway.

Thank you all for your replies.
I am looking for the multi-plane version of the 4-run method. The latter (4-run) is a 1-plane method and I agree that you can do it by scribing the circles on a piece of paper, even though it is included in some commercial vib analysis softw packages (e.g. MasterTrend). Of course you can do 1-plane at a time, but I don't think that it is the same...
In the book of V. Wowk on balancing, there is a reference on a paper by prof. L. J. Everett of Texas A&M Univ. which extends the 4-run method to 2-planes (requires 7 runs), but it is a paper of 1987 and hard to find. I think the paper by Bill Foiles is the answer.
Bill, I suppose that your method extends to a number of planes >= 2, correct?

Regards to all

There were two papers, as I recall, in the 87 (or there abouts [It has been too long.] Could be a journal paper too?) ASME Conference on this - one wasn't presented as I remember. That conference also had a paper on balancing without amplitude, using phase only (Also, a journal paper in 88).

For n plane exact point balance it takes 3n+1 runs. 4 runs for 1 plane, 7 runs for 2 planes, 10 runs for 3 planes, etc.

My method extends it to areas where no man will go, even to least squares type solutions.

The numerical method is fairly simple with programs like Matlab and Scilab (Mathcad, too if you like it - don't forget Maple. works easier with programs like Scilab and Matlab and only involves a psuedo-inverse, pinv() in these programs, other approaches solve it also).

There are other open source, free alternatives to Matlab besides Scilab. Try googling "open source matlab".

No offense to the OP, but is it just me or is there a lot of recent interest in balancing without the use of phase analysis?

Granted that there may be certain situations where it is warranted, but I'm not a big fan of placing random trial weights on the machinery that I monitor. I'm not saying that I've never put a trial weight in the "wrong" spot, but this approach seems inherently risky, especially if you are starting with "large" amplitudes. Just my two cents!

Not to be misunderstood, I agree with Steve. One does not want to overuse this method. I find very little need for it.

My main interest has been to understand balancing better. This is not very efficient for most situations.

I use the classical 1 and 2-plane vector methods. However, I am looking for this method as an alternative for use in cases of machines which work very close to a critical speed or near resonance...

Why?

I would maintain that phase is even more necessary on machines that run close to a critical or near resonance, and in that case I would be gathering transient amplitude and phase as well (amplitude and phase vs rpm during a startup or shutdown).

I disagree with the statement which suggests No Phase Balancing is of academic interest only. In practice the 4 Run No Phase Balance as shown at VibroNurse produces superior results particularly on fans as this method negates any effects of variable stiffness between planes. The downside of increased vibration during the trial runs is not a problem provided the machine has rolling element bearings and is not running above 5000RPM it's only for a short run. In our company we use both VibroNurse Single Plane with phase and the no-phase balance program.

If a machine is running close to resonance, then it is wise to avoid random trial weight placement. I have used convential 1 & 2 plane vector balancing on low speed (2-speed fan) and even with coast-down data (including just bumping the motor) so I can make an educated guess of the heavy spot and make good trial runs. I have the no-phase method available, but I have little use for it. I respect anyone who can quickly and safely balance a machine by Any Method they choose.

Walt

Balancing identical fans (or even the same fan repeatedly) using phase angle allows influence coefficients to be determined so that future balances can usually be achieved with a 'one shot approach'.

There's no doubt that the 4 run, no phase method works but...time is money

quote:

I disagree with the statement which suggests No Phase Balancing is of academic interest only. In practice the 4 Run No Phase Balance as shown at VibroNurse produces superior results particularly on fans as this method negates any effects of variable stiffness between planes.

I assume that I know as much about the theory regarding the 4-run method as anyone, having extended the method in various ways. "Negates any effects of variable stiffness?" Why is this a problem in the first place for any linear method? One might want to use two planes or more, and (full) influence coefficient
methods are superior.

quote:

The downside of increased vibration during the trial runs is not a problem provided the machine has rolling element bearings and is not running above 5000RPM it's only for a short run. In our company we use both VibroNurse Single Plane with phase and the no-phase balance program.

What does operating speed have to do with putting the weight in the wrong location, which is often the result from not using phase? Assuming one is balancing because (duh) the vibration is high, making the vibration higher doesn't sound very good to me.

I stick by my earlier comments regarding limited use.

When balancing, there are sometimes non-linearities which will give less than perfect (repeatable, predictable) phase/amplitude data from run to run. This will give less than perfect solutions when using phase amplitude data, so it can be tedious at times.

However, the same non-linearites are going to exist when using a no-phase method, so the results from that method cannot be more exact than when using phase measurements.

When running near resonance, it is not the phase which changes from run to run (unless the system stiffness is changing), but usually the amplitude which is suspect.