Vibration Condition Monitoring

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
OHS

• 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

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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

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Instrumentation
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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
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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.