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Vibrations analysis

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  • Vibrations analysis

    Anyone here have experience with Vibrations analysis? For bearing failures, blancing, etc


  • #2


    • #3
      yes also trained at Manchester Uni.

      but you would need a fast fornier analysis uint

      best use a screwdriver as a stethoscope HF noise bearing bad quite hiss OK bangs and clicks bad

      used it at work ( to reduce staff levels ) to monitor a large HVAC plant for computer ops for a big bank you need to know the MTBF for the unit and measure at a time interval to suit ,eg we measured at weekly intervals but it still missed the failure

      Last edited by Blackadder; 10-19-2010, 08:01 AM.


      • #4
        Just a side note on stethoscopes --- get a real mechanics one instead of a screwdriver handle - Iv used the latter in a pinch but it always makes me nervous to have something that you are putting one end around rotating objects and not even able to see it when holding it to your ear,
        Much better to have a unit with a flexible hose so that even if it slips and catches a pulley it won't end up inside your brain...

        I think horror freight sells them for something like 5 bucks, your neurons will love you for it.


        • #5
          well i bought a unit

          I bought a unit from Pruftechnik. Got my intor course and i was quickly over my head. Haha. The uint i have also does balancing. I am thinking of selling the vib analysis as a preventive maintenance service. I have a market in mind, i was just wondering who here has used one.


          What was the failure?

          Nothing is fool proof



          • #6
            I have been doing vibration analysis for many years and run the program at my plant. If you are overwhelmed with the intro course, I would not recommend going out on your own until you have more experience. Actual machinery vibrations are quite often more difficult to diagnose then the examples given in the courses, and if you miss something, you will be known as the guy that let a failure happen. You also do not want to be the guy that cries wolf by calling everything that looks like it might be a problem coming.

            You should not even consider balancing someone else's machine until you have training in it and practice, practice practice! You can do a lot of damage to the machine if you do something wrong. I've seen machines with correction weights welded all over the impeller from someone that did not have enough experience to know what to do. Something to keep in mind, in many cases, unbalance is not the problem and trying to balance the machine will just lead to frustration for you and your former customer.

            I don't want to crush your dream, but vibration analysis is not as easy as it initially seems. To help you get the experience, you can read many of the books on the subject, visit the Maintenance Forums if you have not already and make a test unit for practicing finding bearing faults and doing a balance job. For balancing, you will want to try overhung rotors as well as between bearings, the balancing is different.


            Good luck with your analyzer, the Pruftechik units are good and their laser alignment units are top notch.


            • #7
              yup exactly what i thought

              i quickly realised i am no where near offering my services yet. I will have to take the course, $1700.00 ugh. Hopefully there will be one in the spring. Until then it will be learning and testing.

              For Balancing. I figured i could use the face plate of my lathe. Bolt a part on and rotate it. They try to balance it.

              I have a customer i go to every month for a preventive maintenance program. I figured i would start by taking readings off of those motors and see if i could find patterns etc, that match my hands on experience.

              I have about 400 pages of material that was giving to me by one of the salesman, so that should keep me busy this winter!

              I am hoping to be able to offer my services in the spring / early summer.

              I was looking for kindered spirits



              • #8
                Originally posted by spkrman15
                Got my intor course and i was quickly over my head.
                I am hoping to be able to offer my services in the spring

                is this legal?
                in Toronto Ontario - where are you?


                • #9
                  Now don't confuse my lack of knowlege on a subject, for an inability to learn it. I will NOT offer my services unless i am confortable with the equipment and how to interpret the information.

                  I honestly thought the software would compare and analyze the data, but no, that is up to the user. So i will have to take some classes to help me with that aspect. No biggie.

                  I understand your concerns.



                  • #10
                    Sorry if I came across a bit harsh, I have run into many "vibration analysts" that did not have the experience to do the job correctly, I wanted to make sure you did not do the same and jump in before you are ready.

                    Since you are doing PMs at a customer already, that would be a great place to take some readings and practice. The software is much better then it was 10 years ago, but it still takes an analyst to interpret the readings since so many vibration signals look alike until you dig deeper. Just last week I missed a problem due to the levels being low, but the pattern was there. We were replacing the bearings and housings anyways during our outage, but I was surprised at the level of wear with such low level vibration signals.

                    Some things you will want to get experience with is:
                    Unbalance signals of overhung rotors vs between bearings (hint, the axial readings are important here)
                    Understand demodulation and why you may not want to call a bearing fault when you first see it
                    Learn the differences between coupling types and what kinds of vibration signals they generate.
                    Learn all you can about motors, many of the vibration problems you will come across will be in the motors.

                    Since you have a machine shop, you can build something like this to help you learn the different vibration signals and practice.


                    The lathe is a good place to start learning balancing, you can build a disk with tapped holes for balancing weights and make an overhung rotor and then try it also between centers to see the difference. Building something like the simulator above will make it more realistic though.

                    Look into the Vibration Institue, there may be a local chapter near you that offers seminars and training classes, you don't have to use the equipment manufacturer for this. You can also look into Technical Associates of Charlotte, they offer certification classes and exams as well.

                    To answer McGyver's question, in the US it is legal to offer your services without any qualifications, I don't know about Canada. There are no organizations regulating it and it is up to the customer to decide who they want to hire. One way most companies avoid the fly by night operations is requiring a $1 million or more liability insurance before you are allowed to work in their plant.


                    • #11
                      Rob, sorry it wasn't clear; my response was not serious. The typo "inter course" and in over my head struck a funny bone, i wasn't commenting on whether what you intend to do is legal, your learning abiltiy or how you're going about it. just making a crack.
                      in Toronto Ontario - where are you?


                      • #12
                        Mcgyver..holy crap i did not catch that! Too funny.


                        Thanks for the advice. i will most likely start reading some material on the week-end. Be ready for me to ask some questions and for some advice. What machine and software are you using?


                        • #13
                          Feel free to email me any time you have some questions, I would be happy to help.

                          I use a Commtest VB7, not quite as nice as the CSI units, but it did not cost $45,000 like the CSI does. CSI also wanted to charge a yearly maintenance fee of about $8,000 for product support if memory serves me and the Commtest support is free. I used a Commtest at my past job and was happy with it, so far it has done everything I needed.

                          I seemed to have forgotten to put the links for the Vibration Institue and Technical Associates in my past post.


                          TA has a very good wall chart of common vibration problems, not cheap, but nothing in the vibration world is.