Condition Monitoring Expert Tip #4 by Mobius Institute

This tip is sponsored by IMVAC (International Machine Vibration Analysis Conference)

There is no doubt that technologies such as vibration analysis, oil analysis, ultrasound and infrared are very powerful. They can tell you a great deal about fault conditions in rotating machinery, electrical systems, and more. But if the criticality warrants it, you will be in a much stronger position if you have multiple technologies indicating that a fault condition exists rather than relying on just one.

For example, if vibration analysis indicates there is a problem in a gearbox, oil analysis can confirm the fault with the presence of wear particles. In the case of vibration analysis, you can utilize high frequency analysis, spectrum analysis, time waveform analysis, and phase analysis to enable you to validate your diagnosis.

There can be a great deal at stake when you make a diagnostic call on a piece of equipment. More so if it is critical equipment. At the very least, a false diagnosis may lead to equipment failure (if you miss the fault condition) or it can lead to unnecessary work and downtime. What’s more, your reputation is at stake. Sadly, people often forget when you make the right call, but it can take years for people to forget when you make the wrong call.

Thanks Mobius Institute for sharing such valuable information with us!

by Ana Maria Delgado, CRL

What are some of the most common techniques that should be used every day in a vibration analysis program?

  1. Spectrum Analysis
    Spectrum Analysis is used to help identify the normal operation frequencies of a machine. Additionally,  the defect frequencies and their characteristics can be routinely identified.
  2. Waveform Analysis
    Waveforms are one of the most overlook analysis tools. Waveforms can be used to identify fault patterns of equipment defects and help determine the severity of the defect.
  3. Trend Analysis
    Trend Analysis is a critical part of any vibration analysis or condition monitoring program. Trend analysis will help identify fault trends in equipment that may have gone unnoticed otherwise. Also, trend analysis can be used to help identify the severity and rate of progression of identified fault conditions.
  4. Band Alarming
    Carving up the entire spectral range into significant bands and setting alarms to indicate when a problem might be beginning is a good way to optimize the time of analysts and efficiency of a vibration analysis program. This method can prevent fault conditions from being overlooked.
  5. Shock Pulse
    Shock Pulse is a way of harnessing the resonant properties of sensors to gain valuable defect information. This method can be used for early warning of bearing defects and to identify lubrication related issues.
  6. Envelope Demodulation
    Enveloping is a generally valuable early detection method for anti-friction bearing defects and specifically very valuable for detecting such flaws in low and very low speed equipment.
  7. Phase Analysis
    Phase analysis can be incorporated into everyday route data collection. This data can be used to distinguish between different faults that may have similar characteristics.

by Trent Phillips