KCF Technologies Blog

All Vibration Monitors Are Not Alike: Troubleshooting vs. Predictive Maintenance

Ken Piety is the Vice President of Technology at Massachusetts-based Azima DLI, which "delivers machine health reliability solutions with global reach that reduce risk, improve safety, increase production, and optimize efficiency" at pulp and paper plants and other facilities that use rotating machinery.  Piety also narrates a brief but brilliant little video titled "Why Vibration Troubleshooting Instruments are Inadequate for Predictive Maintenance" (PdM) on the Reliable Plant website and on YouTube.

"Sometimes the distinctions can be confusing," Piety says, noting that tools involved in both troubleshooting and PdM, "often do the same tasks.  Both instruments often measure vibration, frequently [taking] detailed measurements like vibration frequency spectra...and both instruments have software associated with them, and may do detailed fault analysis.  However, the fact that there are many similarities does not mean the instruments are capable of accomplishing the same purposes."

"With predictive maintenance...you are able to have a current and up-to-date indication of the health of your machines, and to do that it's important that those machines be screened or scanned on a periodic basis, that their state of health be evaluated....It's extremely important in a predictive maintenance program to capture machines that are beginning to fail at a very early stage.  Often we talk about this as incipient failure detection, and we may be able to capture the fact that the machine is going to fail weeks--perhaps even months--ahead of time."  Accurately anticipating such failures before they happen means parts can be ordered and needed maintenance scheduled when it is most convenient, thus maximizing uptime.

"For a predictive maintenance program, it's common that, perhaps on a monthly basis, a technician will go out and screen these machines with a vibration analyzer, collecting large quantities of data, bring those back, scanning the information, and determining out of the hundreds of machines that you collected data on, which of the few machines may have developed a problem.  [The technician's] task then is to analyze that information, and determine what are the specific faults , and recommend the actions...that need to be taken to correct those faults, and what are the priorities of those actions."

"This is where the overlap begins with a troubleshooting instrument," which is, Piety notes, "capable of collecting and analyzing vibration data, and trying to make a determination of what's wrong with the machine.  However...if you haven't been screening on a periodic basis, how do you know when to do that?"

"Typically, the fault [that the troubleshooting instrument detects] is going to have to be in an advanced enough state that it's been detected by people just from their ears, or their eyes, or the smell of something burning, so it's in a very advanced state.  Even though you may be able to analyze what is wrong with the machine, there's less time to be able to take action and correct that in a way that will not cause the plant to be shut down or to have to reduce production."

"Summarizing," he concludes, "I would say that...vibration analyzers that are used for predictive maintenance programs and those that are used for troubleshooting have many similarities, but the goals and what they can accomplish for you are vastly different.  A troubleshooting instrument is used in an isolated situation to solve a single problem, versus monitoring large numbers of machines in order to optimize the maintenance that is performed in your plant."

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