AXILINEVibration analysis: measuring and assessing equipment condition
Not every vibration calls for an immediate repair. Sometimes what's needed is different: an accurate measurement, a comparison against criteria, and a document with a clear finding. AXILINE carries out on-site vibration measurement and analysis across Portugal. We only make a correction once the measurements have justified it.
When you need a measurement, not a repair
This service is for situations where the main deliverable isn't removing vibration, it's the numbers and the finding. We come out with the instrument, take readings on the running machine, and write up a report. No need to dismantle the equipment.
- Acceptance after a repair or installation. The reading records the condition the contractor handed the machine over in, while the claims period is still open.
- Pre-season checks. Ventilation, chillers, drying lines: a measurement before peak load is cheaper than a failure at the height of the season.
- Justifying a repair. A level in zone C (under ISO 20816, "unsuitable for continuous operation") convinces management to release a budget better than the words "something's humming".
- A baseline level for a trend. The first reading on a sound machine becomes the reference point that every future measurement is compared against.
- A dispute with a contractor or supplier. An independent measurement stating the points, band and mode is hard to argue with.
What we measure
Overall vibration velocity
The level in mm/s RMS over the 10-1000 Hz band at every point. The primary figure for condition assessment under ISO 20816: it adds up everything the machine vibrates with.
1x running-speed component and phase
The part of vibration right at the rotation frequency. Its share of the overall level shows whether unbalance is to blame. Phase helps tell unbalance apart from other causes at the same frequency.
FFT spectrum
Vibration broken down by frequency. Peaks at 1x, 2x, harmonics, blade-pass and bearing frequencies point to the probable cause. We've covered how to read these peaks in our article on reading a vibration spectrum.
Time waveform
The shape of the oscillation over time. Impacts, rubbing and modulation (a periodic strengthening and weakening of the oscillation) show up more clearly in the waveform than in the spectrum.
Speed and mode
We record the rotation frequency with the laser phase sensor referenced to a marker on the shaft. We log load, temperature and the position of control elements (dampers, valves) in the report: without the mode, the result has nothing to be compared against.
Where and how we fit the sensors
The Balanset-1A measures with two accelerometers at once, so we take pairs of points in a single run. We fit sensors on the bearing housings: the nearest rigid point to the bearing, through which the forces from the rotor pass. Plastic covers, thin lids and guards aren't suitable for measurement.
- Points: every accessible bearing housing on the machine and its drive.
- Three directions at each bearing: vertical, horizontal and axial. Faults show up differently, for instance misalignment is often most visible in the axial direction.
- A rigid sensor mount: a magnet or a stud on a clean, flat spot, free of thick paint and dirt.
- Repeatable conditions: the same points, the same mode and load, the same frequency band on every subsequent measurement. Otherwise there's no trend to build.
We mark the points and record them in the report, so the next measurement, ours or yours, lands on the same grid. We've covered typical measurement mistakes in our article on how to measure vibration correctly.
Sources: Balanset-1A manufacturer specification · Balanset-1A operation manual
How we assess the result: zones A-D
We compare overall vibration velocity against the assessment zones of the applicable part of ISO 20816 (formerly the ISO 10816 series). The zones describe the machine's condition and point to an action.
| Zone | What it means | What to do |
|---|---|---|
| A | The level of a new or just-repaired machine | Operate. Record it as the baseline level |
| B | Acceptable for continuous operation | Operate, monitor the trend |
| C | Unsuitable for continuous operation | Plan a shutdown, find and fix the cause |
| D | Risk of damage to the machine | Take out of service, act immediately |
The zone boundaries depend on the part of the standard, the machine group, the power, and how flexible the supports are. We select the applicable part and edition of ISO 20816 for each specific machine and state it in the report; for small units and special machine types we check applicability separately. See our article on ISO 20816 vibration limits for indicative values.
Sources: ISO 20816-1:2016
Why a trend matters more than a single number
A single absolute number says less than it seems to. A machine in zone B might run stably for years, or it might have reached that zone in a month, coming from zone A. The second case is far more alarming, even though the number on screen is the same.
That's why ISO 20816, alongside the zones, introduces a second criterion: the change in vibration level. A noticeable rise from an established baseline level calls for attention even while the absolute value is still within zone B.
The practical takeaway: the first measurement is worth taking on a sound machine, not once it's already shaking. We've described how to set up regular monitoring with setpoints in our article on vibration monitoring, routes and baseline levels.
Sources: ISO 20816-1:2016 · ISO 13373-3:2015
What you get: the report
The result of the service: a measurement report that lets another specialist repeat the measurement and correctly compare the figures. A table of levels without this data is nearly useless.
- A diagram of the machine marking the measurement points and directions.
- Units and band: mm/s RMS, 10-1000 Hz.
- The operating mode at the time of measurement: speed, load, temperature, position of control elements.
- Overall levels at every point and direction, plus 1x amplitude and phase.
- Spectra and time waveforms at points where there's something worth looking at.
- A zone assessment stating the applied part and edition of ISO 20816.
- A finding: operate, monitor at a stated interval, or fix the cause, and which cause to check first.
Where the method doesn't work: we say so plainly
- A one-off measurement doesn't predict remaining service life. A single point in time can't tell you how much longer the machine will run. Only a trend built from several measurements under matching conditions gives a forecast.
- The 10-1000 Hz band doesn't catch the very earliest rolling-bearing defects. Incipient damage shows up at high frequencies and gets buried in the overall level. We additionally look at the spectrum and time waveform, but an early-stage bearing diagnosis from a single measurement can't be promised. More in our article on diagnosing bearings from vibration.
- A non-steady mode hampers the assessment. When speed and load drift, the levels aren't comparable. We take the measurement at a settled operating mode, and if there isn't one, we state that limitation plainly in the report.
- Very low and very high speeds call for a separate approach. Common zone tables are written for typical ranges; outside them, the figures can't be applied blindly.
- Measurement doesn't replace a repair. If the machine is in zone D, the report only records the fact. What follows needs a correction: balancing, shaft alignment, tightening fastenings, or replacing components.
Sources: ISO 13373-3:2015
Travel terms
AXILINE is based in Vila Nova de Gaia (Porto), and we travel across Portugal. The first 20 km are included, beyond that 0.60 EUR/km round trip. The minimum invoice per visit is 500 EUR, minimum time on site is 4 hours. Payment: 50% upfront. All prices are + VAT (charged at the applicable rate). A written report is included in the vibration diagnostics.
If the measurements show unbalance, balancing can often be done in the same visit with the same instrument. The 300 EUR diagnostics would have balancing from 250 EUR added on top, by rotor size: a small fan up to 15 kW would come to 550 EUR all in.
How to order a measurement
Write to us on WhatsApp or call: +351 931 831 229. Email: axilinegeral@gmail.com, Instagram: @axiline.pt. Attach a photo of the machine and its nameplate, state the power and speed. We'll reply with what and how we'll measure, and what the visit will cost. Measurements are carried out by engineers who design and manufacture Balanset instruments themselves and use them for on-site balancing themselves.
- 01
Describe the machine
Send a photo of the unit and its nameplate data, the power, speed, bearing type, and what's concerning you: rising noise, vibration after a repair, an upcoming acceptance.
- 02
We agree the scope
We'll define the measurement points, modes and the applicable part of ISO 20816, and quote the cost of the visit.
- 03
Measurement on site
We work on the running machine, no disassembly needed. To measure the 1x phase we briefly stop the unit and stick a reflective marker on the shaft.
- 04
Report and finding
You get a report with the points, units, band, mode and a clear finding: operate, monitor, or fix the cause.
Frequently asked questions
How does vibration analysis differ from balancing?
Vibration analysis doesn't touch the machine: you get measurements, a comparison against the ISO 20816 zones, and a finding. Balancing fixes one specific cause, unbalance, by fitting correction weights. Analysis often shows that balancing isn't needed at all, and that the cause of vibration is misalignment, loose fastenings or a bearing.
Do I need to stop the equipment for the measurement?
The main measurements are taken on the running machine in its normal mode. A brief stop is needed once: to stick a reflective marker on the shaft for the laser phase sensor, if measuring the 1x phase is required. No disassembly needed.
Which vibration limit applies to my machine?
There's no universal figure. The boundaries of zones A-D depend on the part of ISO 20816, the machine group, the power, and how flexible the supports are. We select the applicable part and edition for each specific unit and record the choice in the report. We've covered indicative values and the selection logic in our article on ISO 20816 vibration limits.
Can you tell me how much longer the bearing will last?
No one can name an exact date from a single measurement, and we won't try. The working tool for a condition forecast is the trend: repeat measurements at the same points and modes, which show the rate of degradation. The first measurement sets the baseline level, and everything after that is compared against it.
Can I take these measurements myself, in-house?
Yes. We supply the Balanset-1A instrument (1975 EUR + VAT): two accelerometers, a laser phase sensor, a two-channel USB module, and Windows software with vibration velocity measurement, an FFT spectrum and a time waveform. The instrument suits regular monitoring of your own machine fleet, and we provide consultation support on the measurement method.
Related content
Industrial vibration diagnostics
Vibration diagnostics is the search for the cause of vibration through measurements on a running machine. We take vibration readings at every bearing housing in three directions, analyse the spectrum, the time waveform and the phase, and cross-check the data against the operating mode and the unit's history. You get a finding with ranked causes and an action plan. If the cause is unbalance, we balance it in the same visit.
How to find the cause of equipment vibration: a methodology, not a list of causes
The cause is found not from a single spectrum (the breakdown of vibration by frequency) but from the whole set of signs together: context (what changed and when it started), how reliable the reading is, the ratio of vibration across all bearing supports in three directions, how the frequencies relate to running speed, the shape of the time waveform, repeatability, and phase — the angle showing at what point in the turn the vibration reaches its peak. You gather this data first, then formulate a single hypothesis, and test it with one controlled action. The diagnosis is not made by the instrument — it comes from the combination of the signs, the machine's behaviour, and a confirming check.
On-site balancing of electric motor and generator rotors
Yes, we balance electric motor and generator rotors on site, in their own supports, at operating speed. Three conditions apply. First: the vibration has to be dominated by the 1x running-speed component — vibration at the rotor's rotational frequency, the main sign of imbalance — rather than by line frequency and its second harmonic. Second: at least one correction plane needs to be accessible, meaning a spot where a weight can be fitted: usually the cooling fan, the coupling, a balancing ring, or the rotor face. Third: the fits, bearings, and fasteners have to be sound, because weights don't cure play. If the rotor is coming off anyway (rewinding, bearing replacement, restoring the mounting surfaces), it makes more sense to balance it on a machine in the workshop, and we'll say so plainly rather than fit weights through a hatch.
Describe your equipment and the problem
We'll answer your questions, clarify the details, and let you know what's needed for an estimate and a visit.