Vibration Analysis

Vibration Analysis and Monitoring

Vibration analysis measures what a machine is doing and compares it against what it should be doing. Overall vibration levels answer the urgent question of whether a machine is in trouble; spectral analysis answers the more useful question of what exactly is wrong. The two together turn a reading into a diagnosis and a diagnosis into a repair.

The long-term value lies in the trend. A single acceptable reading can hide a slowly developing fault, but the same measurement taken consistently over months will show the change before an alarm ever fires. That is what turns condition monitoring from a report into a maintenance strategy, and it is why measurement points and instrument settings are held consistent so that one survey remains directly comparable with the next.

Vibration analysis detects:

• Unbalance, and how it is changing over time
• Angular and parallel misalignment, confirmed by cross-channel phase
• Mechanical looseness, structural looseness and resonance
• Early-stage rolling-element and gear defects, through envelope and demodulation analysis
• Bearing defect frequencies checked against the machine''s specific geometry
• Bent shafts, coupling problems and gear mesh problems
• Transient events such as starts, stops, load changes and switching

Methods and Applications

Measurements are taken as overall velocity, acceleration and displacement, and as a frequency spectrum extended beyond the standard band where a defect is suspected. Envelope and demodulation analysis is applied where bearing or gear condition is in question, and time waveform and phase measurement, including cross-channel phase, is used to separate faults that produce similar overall levels. Every finding is cross-checked against other indicators such as lubricant condition, temperature and current, and against any recent work carried out on the machine, before a fault is named.

Each survey reports overall levels and spectra for every measurement point, referenced to the machine''s speed and bearing frame since every acceptance limit depends on them, a severity classification against the applicable acceptance criteria, a diagnosis with the specific evidence that supports it, and a prioritised action with a deadline. A repeatable measurement route sheet is issued so future surveys remain directly comparable, and the data is stored for trending with the previous survey included for comparison.