Vibration For Non-Vibration Engineers.pdf
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This document discusses vibration monitoring techniques for non-vibration engineers. It describes different maintenance strategies like run-to-failure, preventive maintenance, predictive maintenance, and proactive maintenance. Predictive maintenance uses vibration monitoring to detect abnormal operation and reduce unplanned downtime. Various vibration monitoring methods are outlined, including route-based methods like vibration analysis. Time and frequency domains are discussed, as are displacement, velocity, and acceleration amplitude measurements. Key vibration terms and the importance of choosing the right transducer for the application are also summarized.
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Vibration For Non-Vibration Engineers.pdf
- 1. VIBRATION FOR NON VIBRATION FOR NON VIBRATION ENGINEERS VIBRATION ENGINEERS
- 2. ©2005, Emerson Process Management. Types of Maintenance Strategies Types of Maintenance Strategies Run to failure Preventive maintenance Predictive maintenance Proactive Maintenance
- 3. ©2005, Emerson Process Management. Run to Failure Run to Failure Results in: – Catastrophic machine damage – Unscheduled maintenance – Lost production revenue
- 4. ©2005, Emerson Process Management. Preventive Maintenance Preventive Maintenance Better than “Run to failure” Results in: – Excessive scheduled downtime – Unnecessary maintenance – Failures due to improper maintenance
- 5. ©2005, Emerson Process Management. Predictive Maintenance Predictive Maintenance Maximizes motor life through abnormal operation and fault detection. Reduces unscheduled downtime by alerting users of degrading mechanical/electrical conditions. Optimizes motor utilization.
- 6. ©2005, Emerson Process Management. Predictive Maintenance Methods Predictive Maintenance Methods Route based methods – Vibration – Tribology – Shaft Current/Voltage – Electric Current Analysis – Temperature – Flux – Ultrasonics – Infrared Thermography – Wireless
- 7. ©2005, Emerson Process Management. Predictive Maintenance Methods Predictive Maintenance Methods Continuous (on-line) monitoring Off-line testing – Motor circuit parameter testing – Surge testing
- 8. ©2005, Emerson Process Management. Proactive Maintenance Proactive Maintenance Identify repeat failures Determine root causes for these failures Correct root cause to eliminate future failures for the same reason
- 9. ©2005, Emerson Process Management. Introduction to Vibration Objectives Introduction to Vibration Objectives Introduction to Vibration Objectives Define Vibration – What is it, where does it come from? Describe measurement methods Discuss time and frequency – Relationships between the two Examine amplitude measurements – Differences between the three Choose proper transducer – Right probe for the application
- 10. ©2005, Emerson Process Management. Introduction to Vibration Introduction to Vibration Introduction to Vibration Vibration : – Movement of a body about a reference. • Response to some form of excitation • Forcing function
- 11. ©2005, Emerson Process Management. Amplitude Amplitude Amplitude 3 ways to display – All three show severity – Some better than others Displacement – Distance a body moves – Point “A” to point “B” Velocity – Measures the speed – Time from point “A” to point “B” – rate of displacement Acceleration – Total force acting – Change of direction
- 12. ©2005, Emerson Process Management. Sources of Vibration Sources of Vibration Sources of Vibration Imbalance Misalignment Belts Gears Bearings – Rolling Element – Sleeve Looseness Electrical Anomalies Oil Instability Resonance
- 13. ©2005, Emerson Process Management. Choose units for optimum data display Choose units for optimum data display Choose units for optimum data display (D) isplacement Mils Peak-to-Peak (V) elocity In/Sec Peak (A) cceleration G’s RMS D V A
- 14. ©2005, Emerson Process Management. Vibration Terms Vibration Terms Vibration Terms Phase – relationship between two events relative to a reference Amplitude – measurement of energy of a vibrating object Displacement – distance a body travels – units of mils (pk. to pk.) Velocity – rate at which displacement occurs – units of inches per second in/sec (pk.) or mm/sec RMS Acceleration – rate of change of velocity – units of G’s (RMS)
- 15. ©2005, Emerson Process Management. Vibration Terms, cont’d Vibration Terms, cont Vibration Terms, cont’ ’d d Frequency – how often an event occurs per unit time Units – CPS • cycles per second ( Hz) – CPM • cycles per minute – RPM • revolutions per minute – Orders • multiples of Turning Speed
- 16. ©2005, Emerson Process Management. Measurement Parameters Measurement Parameters Measurement Parameters 2 Domains : TIME and FREQUENCY FFT FFT
- 17. ©2005, Emerson Process Management. Time domain data Time domain data Time domain data Helpful : – Calculating frequencies – Detect faults not frequency domain – Confirm / deny suspected anomalies
- 18. ©2005, Emerson Process Management. Vibration – Overall Trend Vibration Vibration – – Overall Trend Overall Trend
- 19. ©2005, Emerson Process Management. JUL AUG SEP OCT Vibration – 1 x RPM Vibration Vibration – – 1 x RPM 1 x RPM
- 20. ©2005, Emerson Process Management. Vibration – High Frequency Vibration Vibration – – High High Frequency Frequency
- 21. ©2005, Emerson Process Management. Vibration – Bearing Frequencies Vibration Vibration – – Bearing Frequencies Bearing Frequencies High frequency peaks – Usually non-synchronous peaks (with sidebands)
- 22. ©2005, Emerson Process Management. Vibration – Time Waveform Vibration Vibration – – Time Waveform Time Waveform Waveform useful for diagnosing bearing faults – Impacts show as spikes
- 23. ©2005, Emerson Process Management. Vibration – Bearing in FFT Vibration Vibration – – Bearing in FFT Bearing in FFT Bearing faults generate peaks at specific frequencies
- 24. ©2005, Emerson Process Management. An effective program... An effective program... An effective program... Choosing the transducer – the right one for the best data Signal processing – time waveform or spectrum Problem detection – examine both sets of data – is there a problem? Diagnosis – what is the source ? – Root Cause
- 25. ©2005, Emerson Process Management. Transducers Transducers Transducers Function – Convert mechanical signal to electrical Three basic types – Displacement transducer – Velocity transducer – Accelerometer
- 26. ©2005, Emerson Process Management. Displacement Transducers Displacement Transducers Displacement Transducers Advantages + – Measures relative movement – good for sleeve brg. machines – very good for heavy machines Disadvantages - – permanently installed – frequency response : DC to 1KHz – power required
- 27. Displacement probes act much like a transformer.
- 28. ©2005, Emerson Process Management. Velocity Transducer Velocity Transducer Velocity Transducer Connection Case Conductor Coil Spring Magnet Damper
- 29. ©2005, Emerson Process Management. Velocity Transducer Velocity Transducer Velocity Transducer Advantages + – best signal to severity ratio – good signal to noise ratio – no power required – single dif. / int. needed – usually pretty hardy Disadvantages - – usually big – heavy – freq. 10 to 2Kz – temperature sensitive – comparatively expensive – magnetic field sensitive – orientation sensitive – wear and temp. changes calibration
- 30. ©2005, Emerson Process Management. Accelerometers Accelerometers Accelerometers
- 31. ©2005, Emerson Process Management. Accelerometers Accelerometers Accelerometers Advantages – broad frequency range – small, light, rugged – ICP needs no signal conditioning – easy to mount Disadvantages – poor as a hand held – limited signal to noise ratio – reads acceleration – power required – double integration needed
- 32. ©2005, Emerson Process Management. Frequency Signature Frequency Signature Frequency Signature Frequency signal is an X,Y plot. X represents the frequency, Y represents the amplitude or magnitude of the signal. The data is divided into 3 categories : Synchronous – NxRPM where N is an integer (phase locked) Subsynchronous – <1 x RPM Non-synchronous – F x RPM where F is >1x RPM but not integer
- 33. ©2005, Emerson Process Management. Causes - Subsynchronous Causes Causes - - Subsynchronous Subsynchronous Another component in the machine Another machine Belt drives Hydraulic instability – Oil whirl, oil whip Rubs – rotor, shaft, wheel Cage – fundamental train - rolling element brgs.
- 34. ©2005, Emerson Process Management. Causes - Synchronous Causes Causes - - Synchronous Synchronous Imbalance Pitch line run-out Misalignment Bent shaft Looseness Blade / vane pass Reciprocals Gears Slot / Rotor Bar pass
- 35. ©2005, Emerson Process Management. Causes - Nonsynchronous Causes Causes - - Nonsynchronous Nonsynchronous Another machine Belt multiples Bearings Resonances Electrical Chains Compressor surge Detonation Sliding surfaces Lube pumps Centrifugal clutches U-joints