Please enable JavaScript.
Coggle requires JavaScript to display documents.
machinery faults diagnosed by vibration analysis Unbalance // Looseness
…
machinery faults diagnosed by vibration analysis
- Unbalance // Looseness
- Bent shaft // * Shaft cracks
- Eccentricity // Misalignment
- Gear defects // Rotor rubs
- Bearing defects // Oil whip & whirl
- Electrical faults
- Cavitation // Resonance
- Belt drive problems
- Hydraulic and aerodynamic forces.
Unbalance
Measurement:
- rotating centerline<PIA>
- geometric centerline<GCL>
Circumstances:
- Static unbalance (PIA and GCL are parallel)
- Couple unbalance (PIA and GCL intersect in the center)
- Dynamic unbalance (PIA and GCL do not touch or coincide).
Eccentricity
- Eccentric rotor
- Bent shaft
Misalignment
- Parallel misalignment
- Angular misalignment
/ sort of detail /
Mechanical looseness
- Internal assembly looseness
- Looseness at machine to base plate interface
- Structure looseness
Resonance
Rotor response
- Case 1 – Running speed ω is much less than critical speed
- Case 2 – Running speed ω is equal to the critical speed
- Case 3 – running speed ω greater than the critical speed
Rotor rubs
- Orbit representation of a rotor rub
Journal bearings
- High clearance in journal bearings
- Oil whirl
- Dry whirl
- Oil whip
Rolling element bearings
- Stage 1 of bearing defect
- Stage 2 of bearing defect
- Stage 3 of bearing defect
- Stage 4 of bearing defect
Gearing defects
- Gear tooth wear
- Gear tooth load
- Gear eccentricity and backlash
- Gear misalignment
- Gears – cracked or broken tooth
- Gears – hunting tooth problems
Belt defects
- Worn, loose, mismatched belts
- Belt/sheave misalignment
- Eccentric sheaves
- Belt resonance
Electrical problems
- Phasing problem (loose connector)
- Stator defects
- Eccentric rotor
- Synchronous motors (loose stator coils)
- DC motor problems
Scope
• Open or short windings of rotor or stator
• Broken rotor bar
• Unbalanced phases
• Unequal air gaps.
Flow-related vibrations
- Blade pass and vane pass vibrations
- Flow turbulence
- Cavitation
Rotor crack
// symptoms of a shaft crack:
- Unexplained changes in the 1× shaft relative amplitude and phase
- Occurrence of a 2× rpm vibration frequency