Vibration analysis has an unhelpful reputation for being impenetrable. It isn't. Strip away the terminology and it's a straightforward idea: every rotating machine has a normal signature, and faults change that signature in predictable ways.
What we are actually measuring
An accelerometer placed on a bearing housing measures how the machine moves — how far, how fast and how violently. We record that as overall vibration level plus a spectrum showing how much vibration occurs at each frequency.
Frequency is the key. Because we know the shaft speed, the number of gear teeth, the number of vanes and the geometry of the bearing, we can predict exactly which frequency a given fault will appear at.
Why faults are so identifiable
A handful of patterns cover most of what we find on an SME plant floor:
- Imbalance — a large peak at exactly one times shaft speed, usually radial.
- Misalignment — energy at two times shaft speed, often with high axial vibration.
- Looseness — a run of harmonics at multiples of shaft speed.
- Bearing wear — high-frequency defect frequencies that don't line up with shaft speed, growing over time.
- Lubrication problems — raised high-frequency noise long before any classic defect frequency appears.
One reading tells you little; a trend tells you everything
A single measurement gives a snapshot with no context — a 4 mm/s reading might be perfectly normal for that machine or a serious change. What matters is the direction of travel. Six monthly readings showing a steady climb in bearing defect energy is an actionable finding; one reading is an opinion.
This is why monthly routes work so well. Consistency of technique, position and operating condition matters more than the sophistication of the instrument.
What good reporting looks like
You should get a plain diagnosis, a severity, a recommended action and a timescale. Not a 200-page spectrum dump. If you cannot hand the report to a production manager and have them understand what will stop and when, it isn't finished.