The Predictive Advantage

By the time an operator can hear a bearing grinding or feel a motor vibrating excessively, the component is already in the final stages of failure. Vibration analysis allows maintenance teams to detect microscopic wear months before catastrophic failure occurs.

Key Measurement Parameters

• Displacement (mils): Measures total movement. Used primarily for low-frequency (< 10 Hz) issues like unbalance in massive, slow-moving rotors.
• Velocity (in/sec): The most common metric for general machine health. Indicates the fatigue-inducing energy. Best for mid-frequency issues (10 - 1000 Hz) like misalignment, looseness, and unbalance.
• Acceleration (g): Measures the rate of change of velocity. Highly sensitive to high-frequency impacts (> 1000 Hz), making it the primary metric for early-stage bearing defect detection and gear mesh issues.

The Frequency Spectrum (FFT)

Overall vibration tells you that a machine is sick; the Fast Fourier Transform (FFT) spectrum tells you why. By breaking down the complex vibration waveform into individual frequencies, analysts can pinpoint specific faults.

For example, if a motor runs at 1800 RPM (30 Hz), a high peak at exactly 30 Hz (1X running speed) strongly suggests unbalance. A high peak at 60 Hz (2X running speed) usually points to misalignment.