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Vibration Condition Monitoring

Vibration Condition Monitoring. Overview of Methods. Maintenance Methods. Method Relative Cost Fix when fail 100% Preventive Maintenance PM 60% Condition Based CM 50% CM + Failure analysis & redesign 30%. CM Methods .

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Vibration Condition Monitoring

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  1. Vibration Condition Monitoring Overview of Methods

  2. Maintenance Methods Method Relative Cost • Fix when fail 100% • Preventive Maintenance PM 60% • Condition Based CM 50% • CM + Failure analysis & redesign 30%

  3. CM Methods Method On load Off load • Visual, Hearing, Touching And Smell X X • Crack Detection X • Leak Detection X • Corrosion X X • Performance Evaluation X • Wear Particle Analysis X • Noise X • Acoustic Emission X • Electric Motor Testing X X • Lubrication X X • Thermal X • Vibration Condition Monitoring (VCM) X

  4. Which machine? • Financial Analysis • Small power tools not cost effective • Major plant permanent monitoring? • Other machines regular screening?

  5. Instrumentation • Transducer • Eddy Current (displacement) • Piezoelectric Accelerometer • Special: SEE, SPM • Conditioning Amplifier • to suit transducer • built in to instrument • Readout/Analyser • Readout, band limited, FFT?

  6. Accelerometer Mounting

  7. Mounting Point

  8. Measurement Location • Measure each vertical position for Trend Analysis • Measure all positions for full analysis, including Tacho / Phase • Convention: number starting at driver 4V 3V 2V 4A 1V 3A 4H 2A 1A 3H 2H 1H Tacho & Phase

  9. Machine Operation • Consistent operating conditions • Loaded, speed • How to detect loading?

  10. OH&S Operator Safety • Location of transducers • Environment while measuring • Safety moving between machines • Emergency procedures • Personal safety equipment

  11. Monitoring • Vertical vibration at each bearing • RMS vibration only • Use trend analysis • Full measurement at each bearing on fault

  12. Trend Analysis Vibration Level V RMS Shutdown level Full Measurement, Analysis & Diagnosis 6 x base level Alarm level Repair 2 x base level Time

  13. Data, Route, Database • Record all data for all points • Regular logical route through plant • Data storage for maintenance intelligence • Data feeds back to monitoring/redesign

  14. Vibration Level Assessment

  15. Action at Alarm Level • CM measurement exceeds criterion • Fault diagnosis • Maintenance Plan • Spares Requisition

  16. Rolling Bearings - Geometry

  17. Bearing Defect Frequencies

  18. Characteristic Spectrum

  19. Plain Bearings

  20. Characteristic Spectrum

  21. Gear Faults

  22. Characteristic Spectrum - Looseness

  23. Characteristic Spectrum - Flow

  24. Resonance • Input vibration that is at or near the natural frequency causes excessive vibration. • About 20% of machines show resonance • May occur with other faults • Can cause excessive energy use • Can cause serious damage

  25. Diagnostic Case Studies

  26. Case Study 1

  27. Instrumentation

  28. Rotor Details

  29. Phase / Amplitude Data

  30. Base Spectrum

  31. Current Spectrum

  32. Case Study 1 • Data analysis confirms likely static unbalance • Consider the type of rotor to further examine the fault • Static unbalance is rare - fault means similar loss of mass at each end (eg complete blade from a rotary planer)

  33. Case Study 2

  34. Machine Layout

  35. Base Spectrum (3V)

  36. Current Spectrum (3v)

  37. Current Spectrum – Better Resolution

  38. Probable Fault • New spectrum bandwidth 5 Hz per line • Large vibration increase at TMF • Gear problem - perhaps excessive wear on one or both gears, failure of tooth hard facing etc. • Check 3H, 3A, 4V, 4H, 4A, 5V, 5H, 5A, 6V, 6H, 6A to confirm.

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