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Inspecting Chains with Ultrasound

August 2, 2010
(Ultrasonics)

Very few people with chain drives have any predictive or even non-intrusive inspection programmes for chains. This is a shame since it is so easy to inspect a chain using ultrasound. As a chain link moves over a sprocket two things happen. Firstly, the chain link bends and secondly a tooth of the sprocket must slip though the link and make contact with the pin. This is all going to introduce friction and therefore ultrasound which will show impulses corresponding to each of these movements, with a degree of periodicity as the chain repeats its circuits:

Fig 1

 

Tip provided by Tom Murphy and Allan Rienstra, Authors of Hear More A Guide to Using Ultrasound for Leak Detection and Condition Monitoring.

Get your copy of Hear More A Guide to Using Ultrasound for Leak Detection and Condition Monitoring

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Comments (4)

  • So chain manufacturers support this predictive tool? Can they provide advice on what a new chain ultrasound should look like or do I need to establish a benchmark when I install a new chain in a particular application? I can see this being useful if you have a history of ultrasounds from new chain installation thru to failure but getting that information could be time consuming.

    1) Posted 10:41 am, 05 August 2010 by Jack Edwards

  • this is the first time i heard that chains can be inspected by ultrasound. i am interesting to know

    2) Posted 9:21 pm, 05 August 2010 by nerelito cauntic

  • I cannot confirm or deny if chain manufacturers support ultrasound as a predictive tool for CBM of chains. The time signal above, which appears with the full story in "Hear More" was captured while doing a walkabout in a plant using an airborne flexible sensor, which is primarily used for leak detection and inspecting electrical cabinets. The dry chain gave such a unique sound that it just had to be shared. Let's face facts. Metal to metal contact can occur in any rotating, or non-rotating installation... it doesn't have to be a bearing, so why not a chain? For that matter, friction need not be created by metal to metal, so why not a flexible coupling? Why not rubber drive belts?
    Do we need to establish baselines from new chain installations? Perhaps, but I agree with Mr. Edwards that this would be time consuming. However we didn't need a baseline to realize that this chain was not right. A baseline wasn't necessary to make the vigilant ultrasound inspector makes notes and file a work order to have the drive visually inspected.
    Future work? We need to gather a series of dynamic measurements from a collection of chains, good and bad, and overlay the time signals to see how far this application can be developed.
    Perhaps this can be a subject reported on at the May 2011 CBM conference in Fort Myers?

    3) Posted 12:23 pm, 06 August 2010 by Allan Rienstra

  • Everybody that I share this information with makes a comment similar to yours, Nerelito.
    Jack, I do not think that a cradle to grave history is necessary - ultrasound allows you to identify a problem, in this case one which could be just as likely to be present on a new chain as on a five-year old one.
    Having a history, allowing you to make comparisons is always a powerful tool in the world of PdM. Comparisons with peers is, I would argue, even more powerful. So, if I have 10 chains and two are quiet (or two are noisy) this should be enough of a stimulus for me to look further.
    Drive chains play a major role in so many industries. I would agree with Allan that scalable, quantifiable time signals gathered from a large number of chain installations would make very interesting material for a future conference.

    4) Posted 2:45 pm, 06 August 2010 by Tom Murphy

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