How to Measure Frequency of Vibration
Learn how to measure vibration frequency with precision. Explore FFT, vibration meters, and tools to detect faults early and improve maintenance.
Understanding how to measure the frequency of vibration is essential for diagnosing machinery faults, performing condition monitoring, and preventing costly breakdowns. Whether you're a maintenance technician, reliability engineer, or plant manager, accurate vibration frequency analysis helps you detect problems before they escalate.
What Is Vibration Frequency?
Vibration frequency refers to the number of vibration cycles per second, typically expressed in Hertz (Hz). Each machine component generates its own vibration signature. By analyzing the frequency, you can identify the type and location of a fault, such as imbalance, misalignment, or bearing damage.
Methods to Measure Vibration Frequency
1. Using a Vibration Analyzer with FFT
The most accurate method to measure vibration frequency is by using a vibration analyzer equipped with FFT (Fast Fourier Transform) capability.
How it works:
- An accelerometer is placed on the machine
- The sensor detects the raw vibration
- The vibration analyzer converts the time-domain signal into the frequency domain using
- You see a frequency spectrum showing dominant
Example: A peak at 60 Hz might indicate motor imbalance if the motor runs at 3600 RPM.
The number of 60 vibration cycles per second is equivalent to 3,600 per minute (60 x 60 = 3,600), which corresponds to 3,600 RPM.
Using a Handheld Vibration Meter
For quick checks, a vibration meter can display frequency, usually alongside amplitude (velocity or acceleration). Some meters offer limited FFT capability or show dominant frequency components.
2. Mobile Apps and Low-Cost Sensors (For Basic Use)
There are smartphone-based vibration apps, but they lack the precision required for industrial use. They're suitable only for basic comparative checks, not reliable diagnostics.
Key Parameters to Watch
- Dominant frequency (Hz): Helps identify the root cause of vibration.
- Amplitude at specific frequencies: Indicates the severity of the fault.
- Frequency multiples (harmonics): Often signal looseness or resonance issues.
- Sidebands around peaks: Can indicate gear wear or bearing defects.
