Time Waveform - Spectrum - Envelope Spectrum
Vibration analysis requires careful consideration of time waveforms and spectra, as misinterpretations can lead to inaccurate diagnoses.
Points to remember while performing vibration analysis
1. Various time waveforms can produce the same spectrum.
2. Same frequencies can be caused by multiple problems. Example - 1x speed component can be caused by - unbalance, misalignment, bent shaft, looseness, soft foot, and resonance.
3. Frequency components indicate sources and amplitudes define severity. BUT, keep in mind, frequencies can be measured incorrectly and misinterpreted. Similarly, amplitudes can also be understated/overstated/misinterpreted.
4. Machines may run at high vibration levels without failing, and may fail at low vibration levels.
5. For accurate diagnosis, time waveform should be studied along with spectra. Only spectrum analysis may result in 20% diagnosis error.