Vibration Analysis
What it is ...
Vibration monitoring is the oldest type of machine monitoring technique and is the detection of the oscillation of a surface or structure up to a frequency of approximately 25 kHz. Vibration is detected and measured by using transducers to convert vibration energy into an electrical signal. The parameters measured are displacement, velocity and acceleration. Potentially all reciprocating and rotating machinery with moving parts can generate vibration and hence can benefit from vibration monitoring.Vibration monitoring and analysis generally requires the identification of two quantities:
- The magnitude (overall level) of the vibration
- The frequency content via the frequency spectrum (and/or time waveform)
Vibration analysis, applied in an industrial or maintenance environment, aims to reduce maintenance costs and equipment downtime by detecting equipment faults. Vibration analysis is a key component in most condition monitoring programmes and is most commonly used to detect faults in rotating equipment (for example fans, motors, pumps gearboxes, compressors, generator sets and so on), such as unbalance, misalignment, rolling element bearing faults and resonance conditions.Three important analysis techniques can be performed:
CertificationVibration data is obtained on new or re-built machinery to ensure that it is operating within acceptable tolerances. If excessive vibration is discovered, then the cause can be remedied before the machinery is put into service.
Potential fault analysis
This is also called ‘predictive maintenance’ and is used to determine the health of machine components. A good assessment of machine health allows one to predict which component is likely to fail first and approximately how long the component will last before fault conditions begin to occur.
Diagnostic analysis
Whereas potential fault analysis is proactive, diagnostic analysis is reactive. It is only performed once a problem has occurred. Once the vibration data has been collected a comparison is made between the calculated fault frequencies and their harmonics and the actual frequencies that dominate the vibration signature. The cause of each fault frequency is determined and corrective measures are taken to correct the problem.
External Resources BINDT Corporate Member and condition monitoring ATO RMS Reliability Ltd has produced the following series of videos describing the process of vibration monitoring and analysis.
Attaching monitoring discs
How would you attach monitoring discs to collect vibration data? This video demonstrates how to properly attach monitoring discs to ensure you collect data correctly and how you would use these to create a pre-defined route for efficiently collecting data. To view the video, click here.
Collecting vibration data
How do you use portable equipment to collect vibration data from machinery? This video explains how you would download a pre-defined route ready to use your vibration analysis tools to collect the required data safely, ready for analysis when you have uploaded the route again. To view the video, click here.
Collecting data from a variable speed machine
How can you accurately collect data from a variable speed machine? The following video explains how you can use lasers to accurately detect the speed of a machine and then to collect data from that machine. To view the video, click here.
Recognising bad data collection
How can you recognise bad data collection? This video explains how it may be possible to collect poor data from a machine, how you can avoid this and why you want to collect accurate data. To view the video, click here.
Analysing vibration data
How do you analyse the vibration data you have collected? This video provides a basic overview of how you could analyse the data collected from machines and how to recognise if a machine may need further investigation. To view the video, click here.
Technological developments
How can technology help with diagnosing faults in condition monitoring? This video explains what motion amplification is, how this tool can help diagnosing otherwise undetectable faults and why this exciting new technology will help predictive maintenance repair faults before they even appear. To view the video, click here.
