Free Engineering Tool #033
Vibration Source Identifier
Interactive diagnostic tool — enter vibration frequency as order of running speed to identify likely fault sources for rotating machinery.
Diagnostic Results
Complete Frequency–Fault Reference
Vibration Frequency Analysis
Every mechanical fault produces vibration at characteristic frequencies related to the shaft rotational speed. By identifying the dominant frequency in a vibration spectrum and expressing it as an order (multiple) of the shaft speed, the most probable fault source can be determined.
Order Calculation
Where f_vibration is the measured dominant frequency in Hz and RPM is the shaft rotational speed.
Common Fault Frequencies
| Order | Frequency | Primary Source | Additional Indicators |
|---|---|---|---|
| 1x | Shaft speed | Unbalance | Stable phase, proportional to speed squared |
| 1x | Shaft speed | Bent shaft | High axial vibration, phase stable |
| 2x | 2 x shaft speed | Misalignment | High axial, 180° phase across coupling |
| 3x | 3 x shaft speed | Severe misalignment | Multiple harmonics present |
| 0.42–0.48x | Sub-synchronous | Oil whirl | Journal bearings, speed-dependent |
| 0.5x | Half shaft speed | Looseness / rub | Fractional sub-harmonics |
| Multiple harmonics | 1x, 2x, 3x… | Mechanical looseness | Many harmonics of running speed |
| Non-synchronous | BPFO, BPFI, BSF | Bearing defects | Modulated by running speed |
| Z x RPM | Blade pass | Flow issues | Pulsation, cavitation |
| Z x RPM | Gear mesh | Gear problems | Sidebands indicate which gear |
| 2x line (100/120 Hz) | Fixed frequency | Electrical | Disappears when power removed |
Phase Angle Guide
Phase analysis is critical for distinguishing faults at the same frequency. At 1x: stable phase = unbalance, 180° across coupling = misalignment, unstable phase = looseness. Always use a tachometer reference.
Practical Example
Given: Running speed = 1500 RPM, Dominant frequency = 75 Hz
Running speed frequency = 1500 / 60 = 25 Hz
Order = 75 / 25 = 3.0x
Primary suspect: Severe misalignment or mechanical looseness
Recommended: Check coupling alignment, inspect mounting bolts, verify foundation
⚠️ Note: This tool provides guidance based on common fault-frequency relationships. Definitive diagnosis requires correlation with phase data, time waveform, orbit plots, operating conditions, and machine history. Always verify with additional measurements.
Professional vibration analyzers with spectrum analysis, order tracking, and fault diagnosis. Used in 50+ countries.
Nikolai Shelkovenko
Nikolai Shelkovenko is a vibration analysis engineer and the founder and CEO of Vibromera. For more than 15 years he has balanced rotating equipment in the field rather than on a test bench: mulchers, industrial fans, crushers, centrifuges, shafts and spindles. That work is what the Balanset instruments grew out of — they were designed as a tool a specialist can carry to the machine and use alone, on site, not as laboratory equipment. Vibromera was founded in 2017 and has been based in Porto, Portugal, since 2023. Development, assembly and support of the Balanset line all happen here. The flagship instrument is the Balanset-1A, a portable analyser for single- and two-plane balancing and for vibration diagnostics. Nikolai is personally involved in customer support, in working through difficult balancing cases and in the development of the software. He works with customers worldwide, in any language.
