Stop Guessing, Start Predicting: A Guide to Vibration Analysis
Figure 1: Typical Vibration Spectrum signatures for common machine faults.
Old-school maintenance was "Run to Failure." You waited for the machine to smoke, then fixed it.
Modern maintenance is Predictive. By listening to the "voice" of the machine—its vibration signature—we can predict bearing failures months before they happen.
This guide covers the fundamentals of Vibration Analysis, the ISO 10816 standard, and the tools you need to build a reliability program.
1. The Big Three: What are we looking for?
90% of mechanical vibration comes from three specific faults. If you can identify these, you solve most plant problems.
A. Unbalance (1x RPM)
The Symptom: A heavy spot on a fan or rotor.
The Signature: A high vibration spike at exactly the running speed (1x RPM). It is typically radial (vertical/horizontal).
B. Misalignment (2x RPM)
The Symptom: Motor and pump shafts are not collinear.
The Signature: High vibration at 2x RPM (twice the running speed) and often high Axial vibration.
(See our guide on V-Belt Drive Design & Alignment for more details on this).
C. Bearing Defects (High Frequency)
The Symptom: Pitting on the ball bearings or raceway.
The Signature: These do not show up at running speed. They appear as low-amplitude "noise" in the high-frequency range (2,000 Hz+). This is why you need a Vibration Meter—you cannot feel this with your hand.
2. Is my Vibration "Bad"? (ISO 10816 Standard)
You measured 4.5 mm/s of vibration. Is that acceptable? The ISO 10816 standard gives us the answer based on machine size.
| Zone | Vibration (mm/s RMS) | Condition |
|---|---|---|
| A | < 1.4 | Excellent (New Machine) |
| B | 1.4 - 4.5 | Good (Unlimited Operation) |
| C | 4.5 - 11.0 | Warning (Plan Maintenance) |
| D | > 11.0 | DANGER (Shut Down Immediately) |
3. Essential Tools for the Reliability Engineer
You don't need a $20,000 analyzer to start. Here are the tiered tools for every budget.
Tier 1: The "Vibration Pen" (Screening)
Every operator should carry one. It gives a single number (Overall Vibration) to compare against ISO standards.
Tier 2: The Stroboscope (Visual Inspection)
A Stroboscope flashes light at the exact speed of the machine, "freezing" it visually. This allows you to inspect belts, couplings, and bolts while the machine is running at full speed.
Tier 3: Wireless IoT Sensors (The Future)
Modern plants are moving to IIoT (Industrial Internet of Things). Small wireless pucks are magnetically attached to motors, sending data to the cloud 24/7.
4. Conclusion: Start Small
Don't try to monitor every bearing in the plant. Start with your Critical Assets—the machines that stop production if they fail. Establish a baseline vibration reading today, so you know when things change tomorrow.
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