Vibration Analysis Basics: How Rotating Equipment Tells You It Is About to Fail

Key takeaways

• Vibration analysis = monitoring rotating-equipment vibration signatures to predict failure.
• Many rotating-equipment failures, bearing, unbalance and misalignment problems in particular, change the vibration signature well before breakdown.
• Common signatures: imbalance (1x running speed), misalignment (2x), bearing defects (high frequency).
• Triggers: rising amplitude, characteristic frequency emergence, comparison to historical baseline.
• Worth the investment on critical rotating equipment. Less valuable on stationary or simple assets.

Why vibration carries failure signal

Rotating equipment in good condition vibrates predictably:

• Some vibration at running speed (always present).
• Low amplitude.
• Stable spectrum over time.

Failures change the pattern:

• Imbalance increases vibration at 1x running speed.
• Misalignment generates 2x running speed component.
• Bearing wear generates high-frequency content.
• Looseness produces broadband noise.

The patterns are characteristic; analysis identifies the failure mode before it produces a breakdown.

What is measured

• Amplitude. How much vibration (mm/s, g, or microns).
• Frequency. What frequencies dominate.
• Trend. Change over time.
• Phase. Relative timing (used in balancing).

Most plants start with amplitude and frequency analysis. Phase analysis is for balancing work.

The common signatures

Imbalance: high amplitude at 1x running speed. Cause: unbalanced rotor.

Misalignment: 2x running speed component. Cause: coupling misalignment.

Bent shaft: 1x and 2x with phase characteristics. Cause: bent or warped shaft.

Looseness: broadband content, fractional harmonics. Cause: loose mounting or worn parts.

Bearing defects: high-frequency content (5x running speed and higher). Cause: bearing element damage.

Gear mesh problems: tooth-mesh frequency (gear teeth x running speed). Cause: gear wear.

What triggers action

1. Amplitude above the ISO 20816 evaluation zone limits or your own baseline alarm. ISO 20816-3:2022 replaced the withdrawn ISO 10816-3 for industrial machines above 15 kW.
2. Rising trend. Even within thresholds, persistent rise indicates degradation.
3. New characteristic frequency. A spectrum component that was not there before.
4. Pattern matching a known failure mode. Bearing signature emerging.

Action: investigate, schedule maintenance, plan replacement.

How vibration monitoring is deployed

Walk-around route. Technician with handheld analyzer reads each asset on a route. Common for medium-criticality assets.

Wireless sensors. Battery-powered sensors send periodic readings. Common for hard-to-reach assets.

Online continuous monitoring. Wired sensors stream real-time data. Common for critical assets.

Cost and value scale with deployment method.

What vibration analysis cannot do

• Predict non-vibration failures (electrical, control, software).
• Catch sudden failures (impacts, debris).
• Replace operator inspection (vibration misses many visible issues).
• Work on stationary equipment.

Vibration is one tool, not the whole solution.

What it works well on

• Motors.
• Pumps.
• Compressors.
• Fans.
• Gearboxes.
• Turbines.

Rotating equipment with bearings, gears, or imbalance risk.

Common mistakes

1. Vibration data without analysis. Sensors deployed; nobody interprets. Data piles up; alerts ignored.

2. Threshold-only alerting. Misses trend signals. Use both.

3. No baseline. Without historical comparison, current readings are unanchored.

4. Universal monitoring. Vibration on cheap assets does not pay back.

Integration with CMMS

Vibration alerts should:

• Trigger a follow-up task for review when a threshold is breached.
• Route to reliability engineer.
• Track investigation and resolution.
• Update asset history with findings.

Without CMMS integration, alerts go to email and get lost.

Cost considerations

Walk-around analyzer: a one-off instrument purchase plus technician time for every route.

Wireless sensors: a hardware cost for every measurement point, plus any software fees.

Online continuous: typically the highest cost per point, plus cabling and infrastructure. Prices vary widely by vendor and specification, so get current quotes.

Scale to criticality. Critical assets get continuous; mid get wireless; lower-criticality get walk-around.

How OEE connects

Vibration catches failures before they produce downtime. Plants with mature vibration programs see Availability move up as catches translate to planned vs unplanned response.

How a modern CMMS supports vibration

A modern CMMS integrates with vibration monitoring systems, generates WOs on alerts, tracks the resolution, and updates asset history with findings.

Fabrico connects to PLCs and IoT sensors, so a vibration reading that crosses a limit can trigger a notification and a follow-up task in the CMMS, and the findings are saved to the asset history alongside MTBF and MTTR analytics.

See how Fabrico captures this automatically, explore OEE for manufacturing or book a demo.

Related reading

• Infrared Thermography Basics

Frequently asked questions

How early does vibration catch failure?

Weeks for bearings; days for some imbalance issues. Depends on degradation rate.

Do I need a vibration analyst on staff?

For mature programs yes. For starting, contract analysis is common.

What is ISO 20816 (formerly ISO 10816)?

ISO 20816 is the ISO series for measuring and evaluating machine vibration. It replaced the withdrawn ISO 10816 series: ISO 20816-1:2016 covers the general guidelines and ISO 20816-3:2022 covers industrial machines above 15 kW. It rates vibration severity in evaluation zones A through D. See our ISO 20816 vibration severity zones guide for the limits.

Should I monitor every motor?

Critical and important motors yes. Cheap motors with redundancy may not pay back.

Is AI vibration analysis useful?

Increasingly. Trained models catch patterns that thresholds miss.