| Symptom (Dominant Peak) | Likely Fault | Action | | :--- | :--- | :--- | | (exact) | Unbalance | Balance rotor or check for mass loss (e.g., broken fan blade). | | 1× RPM (axial direction high) | Bent shaft | Straighten or replace shaft. | | 2× RPM (radial) | Angular misalignment | Align coupling using laser alignment tool. | | 2× RPM + 180° phase shift | Parallel misalignment | Shim motor base. | | High 1×, 2×, 3×... 10× | Mechanical looseness | Tighten foundation bolts, check bearing fit. | | Non-synchronous peaks (e.g., 0.45× RPM) | Oil whirl / Bearing instability | Check oil viscosity, bearing clearance. | | High frequency "haystack" (noise floor rise) | Bearing fatigue / Lubrication failure | Perform Shock Pulse or Enveloping analysis. Replace bearing. |
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This content serves as a complete, practical, and actionable primer on vibration analysis. The Practical Vibration Primer Pdf
Vibration analysis is the cornerstone of modern predictive maintenance. This primer provides a practical, non-theoretical introduction to industrial vibration measurement. It covers the physics of vibration (displacement, velocity, acceleration), sensor selection (accelerometers, proximity probes), basic signal processing (FFT, time waveform), and common fault diagnosis (imbalance, misalignment, looseness, bearing failures). The goal is to equip field technicians and junior engineers with actionable knowledge to reduce machine downtime.
But the technician had read . They remembered the rule: "Never trust a single overall number; look at the FFT." | Symptom (Dominant Peak) | Likely Fault |
Understanding displacement, velocity, and acceleration—the three primary measurement variables.
When they pulled up the spectrum, they saw a very small peak at 1X RPM, but a massive "haystack" of high-frequency energy between 30,000 and 50,000 CPM. The Primer taught them that this "energy hump" is the resonant frequency of the accelerometer being excited by failing bearing lubrication. | | 2× RPM + 180° phase shift
In the world of industrial maintenance, reliability engineering, and mechanical diagnostics, data is worthless unless it is actionable. For decades, beginners and seasoned technicians alike have struggled to bridge the gap between complex vibration theory (filled with calculus and differential equations) and the real-world task of fixing a rotating machine.