Hi,
For some years now I have calculated the vibration index (average vibration in velocity) the whole mill site. It is good to see this trending down over time as our tradesmen get alignments and balance etc better. I have heard various speakers at conferences refer this measure and have heard of a couple of different numbers as what is "world class". Eg 1.5 mm/sec (0.06 IPS) (RMS).

Is there anyone out there measureing this index and what level is it?
What type of plant is it?

Thanks,
Murray

I had to begin generating this number for our papermill vibration databases and report to management each month.

CSI software makes this easy as your able to generate the report off a database group. By grouping all our databases into one group I can then run the report for a certain time span. Generally I run the report once per month.

Our numbers have consistantly ran at .065-.070 in/sec.

It is my thought when you run a number such as this you will see high numbers if you have alot of equipment with imbalance and aignment problems.
Because our maintenance dept has done a great job over the years in both imbalance and alignment issues I do not expect to see our numbers vary.

Mike

Thanks Mike,
I am in a pulp mill. Our index is about 1.40 mm/sec rms. ie 0.055 IPS.

Murray

HI fellows,
I have been generated those number for a little while now. I use the same method as Mike. I build a request on Access that is run by a macro in Excel. The request extracts the data from the RBMware’s database through CSI’s ODBC. I trend the machine’s averages on a graph and compare it to similar machines. The good thing about it is that I do not have anything to do but the push of a button to generate the entire up-dated graph. Manager loves it and its very little work for me. Helps a lot the managers and planner to realise which machine need works and which runs fine without having to be a vibration wizard! If you guys are interested we could arrange something just send me an E-mail. I’ll be out of the office until end of July but I’ll take care of business as soon as I get back.

Best regard, Marcel

broyeur.pdf (1,395 Kb, 150 downloads)

Marcel and others, where are you getting the data? VibTendData? Are you averaging just the velocity points? I forget now how CSI calculates the index--guess I could search the help files.

Marcel,
I downloaded your pdf file and was most impressed.

One of the key things we need to continue to do is keep our managment informed as to how important or work is. They tend to think we are just some techos who absorb a lot of money for little results. It is up to us to let them know what a great job we are doing and how they can not manage with out us. . . which of course is the truth!

The query I had was related a mill (plant) wide index or average. Each month I crunch this number useing export in the CSI software and plot it in Excel. This is the number I am keen to hear from others so that I can get an idea if our's OK or not.

I was most impressed with your report, and will spend some time looking at that on Monday when I am back at work.

Thanks Marcel.

Hi guys,
I have CSI RBMware and i could find an option in the Exception Reports to create Vibration Index..Is it the one you are talking about?But it is giving a big report for each equipment status in a period. How did u get a single index for a datbase(i mean a particular area of the plant)?

About your report Marcel, it seems very nice but unfortunatley i dont know your language . I like to know more about how you are doing it.. Can you please send me some information in my xcm811799@hadeed.com.sa since you didnt mention your e-mail add!!

Have a nice day!!

Hi Jenish,
The way I get the vibration index, is by using
EXPORT - Program Management - Vibration Index report.

Select the options in there that you want. I choose just one month and all alarms.

I have noticed a problem in that it only looks at those in alarm.
You can also extract the data using Export- Data Summaries. From here cut and paste into Excel and do the number crunching. It is more work but comes up with all the relevant data.

Any way guys - can anyone tell me what you believe is a good "standard" or "World Class" vib index?

Murray

It would vary by industry, but when I was in paper, we were shooting for less than 0.07 ips-RMS for the mill overall. That's what our corporate guys were calling world class.

Hi Murray,

I made a vibration index report as you mentioned. It is for 1 month and for a particular route. I'm attaching it. can u tell me whatz the vibration index for mine?

Have a nice day!!

Vibration_Index_Report.doc (50 Kb, 57 downloads) Vibration Index

Hi Jenish,

You seemed to have got it wrong some where.

Attached is Word Doc in which I have placed some screen dumps etc.

I trust this will be of help.

Murray

Vib_Index.doc (168 Kb, 62 downloads) Vib Index.doc

Hello vib folks,
Sorry I had been so long, I just came back from vacation… Kind of hard to get back at it. I forgot the E-mail address; I thought it was on my profile… Oups! First I would like to say that the index found in CSI reporting wasn’t usable for untrained people; so I ask management and planner what they were expecting from a predictive report. Well, they answer we want to know what vibrate and what doesn’t! It could be nice to also have the work order #… I thought at first that it was a dump answer but I decided to go through anyway. The be frank with you, I am the dummy now that uses it the most! When you visualize vibration overall averages from identical machine trended over time, an untrained eyes can quickly spot problem machine from normal machine and newly rebuild! Management and planner can do the same just as easy and the little program makes it even easier to produce from the click of a mouse. If any of you are interested just send me E-mail and I’ll see what can be done and don’t worry the language can be easily changed.

Best regard, Marcel

mbelanger@cci-wabush .com

Broyeurs.pdf (222 Kb, 47 downloads)

Hi vib folks,
I attached the program with the set up instruction for those that uses CSI and are interested. It is easier to set up that it look.

Best regard, Marcel

Predicitve_report.zip (814 Kb, 43 downloads)

quote:

Originally posted by lawrencep:
... we were shooting for less than 0.07 ips-RMS for the mill overall. That's what our corporate guys were calling world class.

Having an overall vibration index for the whole plant as a measure of equipment health does not make any sense, IMHO.

Why? Because it is same as making an assessment about hospital patients health by calculating average temperature hospitalwide. Somebody runs 101F, somebody 96F, but on average temperature is normal... If I add to this picture couple of patients with heart conditions, which do not develop any excessive temperature, you'll get my point.

In the vibration world certain faults (such as bearing defects) do not contribute much to the overall but obviously are very problematic.

"Corporate guys" may like overall numbers but mostly having little understanding of vibration technology they do not realize how little a plantwide index represents.

In my view giving to a manager concrete information and a suggestion generated by a vibration analyst in regards to a problem machine and breaking it down to several severity categories if needed is much more useful.

David

Some find trending of Vibration Index useful. Here is a little comment on that.

Trending in general is a good tool if the parameter being trended is representative. It is well known that vibration overall for an individual machine may show very little variability while a serious problem may exist. So, even for an individual machine the overall vibration is not representative of machine condition, therefore, six or more frequency bands trending is being used by many.

If band trending approach is also applied for a plant wide trending it may become a better plant wide indicator. But even in this case it is more for the reporting purpose to the corporate guys rather then a guide for concrete actions. Unless this is the goal, it does not appear that Vibration Index has significant benefits. Again, individual asset condition evaluation is needed in day-to-day life in a plant.

David

In response to David's comment's,

I tend to agree with what you are saying, and that one needs to trend specific bands on each machine point to be precise.
However, over the years we have also trended the over all Mill vibration index in Velocity.
As we have put pressure on to see better alignments and and balancing etc we have seen this number drift down.

Remember Velocity is a measure of fatigue, so by trying to get an overall reduction we are increasing the life of our machines. We get this reduction by fixing one machine at a time.

Sure the Mill Vib index is "crude" as far as the anaylist is concerned but it does give a general indication of how the whole maintenance dept is doing. I certainly would be worried if the number was drifting up.

Murray

quote:

Remember Velocity is a measure of fatigue

I didn't know this. So, if the velocity reading increases the fatique has increased - what does this mean?

HI vibe folks,
I think we could be arguing for a long time over the implication of the index… Personally it is a mean of explaining in vibration to non-trained people. Yes we do need to analyse data and I always take time to look at each point’s FFT. But we have to consider that at approximately 90% time the index will rise to any defect, it maybe too late by then but it will still serve its purpose of educating untrained people. Further more to some managers take pride to see the number goes down in their department! Still serve its purpose! It is more than enough for me, as long as it helps me increase machineries reliability.

Best regard, Marcel

Hi William,

Generally if a machine is vibrating its life is going to be shortened. If the velocity is high then the load is increased on the bearings etc so the "fatigue" is increased.
There are a number of papers on the net that refer to this.
eg.
www.wyko.co.uk/conditionmonitoring/pdf/VAI.pdf

Bearing manufacturers calculate the life of a bearing by using the following formula:
L10 LIFE (HOURS) = (16,666/RPM) X (RATE/LOAD)3
where: RPM = Machine rotating speed in Revolutions Per Minute
RATE = The rated load capacity of the bearing (lbs.)
LOAD = The actual load on the bearing. This includes not only the static load due to the weight of the rotor, but the dynamic load due to forces of unbalance, misalignment, etc., FORCES THAT CAUSE VIBRATION.

So the the greater the dynamic load the greater the fatigue = shorter life.

Hope this helps a little
Murray

I think this is rather simplistic. It depends upon what is causing the velocity and the nature of the vibration.