Mike Cannon DLI Engineering Automated Bearing Wear Detection DLI Engr Corp - 1
DLI Engr Corp - 2 Vibration: an indicator of machine condition
Narrow band Vibration Analysis DLI Engr Corp - 3 Vibration Contents by Frequency FFT Spectral Analysis Identify Peaks & Patterns - Relationship to machinery components Amplitude of peak comparison to baseline Diagnosis and severity of machine problem Repair recommendations Specific to problem Priority and Remaining life
Time Domain & Frequency Domain Vibration Wave Form A complex signal is the sum of several sine waves V i b r a t i o n S p e c t r u m A m p l i t u d e v s. t i m e F r e q u e n c y DLI Engr Corp - 4
Vibration Data Acquisition & Processing Analog Signal is Digitized Vibration Signal DLI Engr Corp - 5
Forcing Frequencies Rotation Rate of Fan Five-Blades on Fan DLI Engr Corp - 6 Fly swatter against the blades
Forcing Frequencies in Spectra IPS 1X RPM Fly Swatter DLI Engr Corp - 7 0 1 2 3 4 5 6 7 8 9 10 10 Orders 18
Results = Problems Identified Detection Diagnosis & Prognosis Motor Gear Cprsr of specific problems Imbalance Out-of-round Journal Misalignment Gear Problems Bearings (BAD /COCKED) Impeller Blade Problems DLI Engr Corp - 8 Bent shaft Looseness Magnetic Noise Electrical Noise
Accurate results from quality data Triaxial Sensor All 3 axes - more complete analysis Improves accuracy of diagnosis Permanently Mounted Stud Excellent frequency response Repeatability = accurate trending Barcoding Faster and more accurate Prevents human error WATCHMAN TEST POINT 100 100 DLI Engr Corp - 9 DO NOT PAINT
Baseline Data to define the healthy machine 800 Alarm Levels DLI Engr Corp - 10
Order Normalization DLI Engr Corp - 11 Amplitude VdB 140 130 120 110-100 90 80 70 60 Conventional Vibration Spectrum 1800 rpm component 0 3 6 9 12 15 18 Frequency 0-18,000 RPM
Order Normalization Order Normalized Vibration Spectrum DLI Engr Corp - 12 Amplitude in VdB 140 130 120 110-100 90 80 70 60 0 1 2 3 4 5 6 7 8 9 10 Frequency in Orders (multiples of rotation rate)
Results from Vibration Analysis Level LevelII Reports Level LevelIIII Trends Trends DLI Engr Corp - 13 Level LevelIII III Signatures
MCA Results - Summary Report 1. MANDATORY Repair Recommendations AIR CONDITIONING SALTWATER CIRCULATING PUMP #3 Mandatory: Overhaul unit. AUXILIARY MACHINERY COOLING WATER PUMP #2B Mandatory: Align Motor and Pump. 2. IMPORTANT Repair Recommendations MAIN CONDENSATE PUMP (MD) #1A Important: Replace motor bearings. Desirable: Monitor pump bearings for increased vibration. LUBE OIL SERVICE PUMP (ATTACHED) #1C Important: Inspect bevel gears for proper meshing; if satisfactory, check intermediate shaft bearings for looseness. DLI Engr Corp - 14 TURBO-GENERATOR (60HZ) #8 Important: Inspect accessory drive shaft for proper bearing fit and clearances.
Trend Reports Replaced Bearing Increased Frequency of Data Collection DLI Engr Corp - 15 Greased Bearing
Automated Diagnostic Systems Input Internal Functions Output DLI Engr Corp - 16 Vibration sensors Accelerometers & prox probes Process and performance data Portable or Online systems OSI Pi Database FFT spectrum, cepstrum & demod Triaxial, order-normalized data Machine specific, statistical baselines Feature extraction & exceedance tables 4700 fault templates Score & trend specific fault severities Specific faults & severity Repair recommendations Email & pager ALERTs Network replication OPC & XML connectivity Web Connect browser access
Automated Diagnostic System Flow Chart Incoming Spectra Complete sets of high resolution vibe data for FFT, cepstrum & demod What machine is this & what are its vibration sources? Machine configuration data, (VTAGs) coupled with component specific fault templates How does this spectra compare to that of a healthy machine? Feature extraction and exceedance table What, if anything, is wrong with this machine and how bad is it? Detection diagnosis & prognosis DLI Engr Corp - 17 Machinery Fault Report Actionable Information
Component Codes NOTE: This illustrated set is not complete 1 Motor Driven Close Coupled Pumps/Fans 2 Turbines 3 3 Motors Motors 4 Gearboxes 5 Linked Drives (Belt/chain) 6 Pumps Pumps Centrifugal Centrifugal 7 Rotary Thread Pumps 8 Sliding Vane Pumps 9 Axial Piston Pumps 10 Fans DLI Engr Corp - 18 11 Centrifugal Compressors 12 Piston Compressors 13 Generators 14 Centrifugal Purifiers 15 15 Couplings Couplings
Features from comparison to baseline DLI Engr Corp - 19 AVERAGE AVERAGE AVERAGE AVERAGE + + 1 1 SIGMA SIGMA AVERAGE AVERAGE + + 2 2 SIGMAS SIGMAS
DLI Engr Corp - 20 Extracted Forcing Frequencies
DLI Engr Corp - 21 Extracted Bearing Tones (3.1x)
Fault Template Diagnosis Rules Misalignment (Parallel) 1. 2X Radial or Tangential > 95VdB & > 2 VdB above Baseline on both sides of the coupling 2. 2X Radial > 1X Radial or 2x Tangential > 1X Tangential for one side of the coupling DLI Engr Corp - 22 3. The Maximum 2X > 101VdB or The sum of 2X exceedances > 18 VdB for at least one side of the coupling.
Fault Models / Diagnostic Flow COMPONENT CODES MOTOR FAULT TEMPLATES CSDM SCREENING OUTPUT TABLE MACHINE DATA CSDM COUPLING CENTRIFUGAL PUMP CSDM DLI Engr Corp - 23 (CSDM = Component Specific Data Matrix)
Results from Automated Diagnostics Provides the most efficient machinery fault detection, diagnosis & prognosis to insure: Immediate local fault detection & actionable information Optimal asset reliability and machine life extension through prognosis of how & when machine should be repaired DLI Engr Corp - 24
Rolling Element Bearing Detection Fault Indicators in Vibration Spectra Bearing Tones Sidebands Non-integer peaks and harmonics relative to component rotation rate Noise floor elevation DLI Engr Corp - 25 High frequency indicators Impact and Ringing Modulation
Rolling Element Bearing Geometry Snap ring groove Seal/shield groove & notch Ball Inner ring Outside diameter Bore Inner race Cage DLI Engr Corp - 26 Inner ring face Outer ring face Outer race Outer ring
Bearing Tones Ball Diameter (BD) DLI Engr Corp - 27 Pitch Diameter (PD) Ball Pass Frequency Inner Race BPFI Ball Pass Frequency Outer Race BPFO Ball Spin Frequency BSF Bearing Train Frequency FTF
DLI Engr Corp - 28 Rolling Element Bearings
Bearing Tones DLI Engr Corp - 29 Pitch Diameter (PD) n B BPFI 2 1 P BPFO n B 2 1 P P B Bd 2 P d cos RPM cos RPM d d Ball Diameter (BD) BSF 1 cos FTF 1 Bd 2 1 P d d d d d 2 cos RPM 2 RPM
Simplified Bearing Tones Non-Synchronous Components BPFO = Rollers x rpm x 0.4 BPFI = Rollers x rpm x 0.6 FTF = rpm x 0.4 Sidebands Usually 1X Around BPFI May be FTF Around Bearing Tones DLI Engr Corp - 30
Rolling Element Bearings For each shaft revolution: 4.6 balls will pass an outer race defect The ball will make 2.02 revolutions 7.4 balls will pass an inner race defect DLI Engr Corp - 31 The cage will make 0.38 revolutions
Calculated Bearing Tones Bearing tones do not always appear at the expected, calculated frequencies User does not always have correct bearing information Diagnostic System designed to work independently of calculated bearing frequencies User may overlay calculated frequencies on graph if desired DLI Engr Corp - 32
Non-Synchronous Tones DLI Engr Corp - 33 Synchronous Components are integer multiples of shaft rotation rate 140 Bearing tones are non-integer multiples of shaft rate Shaft Rotation Shaft Rate Harmonics Bearing Tone 4.6 x Sidebands 2.6x, 3.6x, 5.6x 130 120 110 100 90 80 70 60 VdB 0 1 2 3 4 5 6 Orders Bearing Tone -- 4.6X
Automated Spectral Peak Extraction Identify Shaft Rate Peak(s) Identify Harmonics of Shaft Rate(s) Identify Forcing Frequencies Identify External Vibration Extract non-defined, non-synchronous peaks as possible bearing tone candidates. DLI Engr Corp - 34
Summary of Analysis Techniques Data Normalization Automated Spectral Peak Extraction Cepstrum Analysis Noise Floor Calculation Rule-Based Diagnostics Demodulation DLI Engr Corp - 35
Cepstrum Analysis The Spectrum of the Spectrum 140 VdB 130 120 110 100 140 CdB 90 130 80 120 70 60 0 10 20 30 40 CPM (x 1000) 110 100 90 Bearing Tones 1X Harmonics 80 70 DLI Engr Corp - 36 60.006.003.002.0015 Time, Seconds
The Cepstrum Extracts Periodicities From the Spectrum Separates Different Harmonic Series Separates Sideband Families Is Useful in Automating Bearing Wear Detection Bearing Model Is Not Required!!! Is this bearing tone candidate part of a family of peaks? # = Yes DLI Engr Corp - 37
DLI Engr Corp - 38 Spectral Data: Bearing Tone at 3.1x
Put it all together (Cont d) 3.1X 6.2X 24.8X 9.3X 12.5X 15.5X 52.7X DLI Engr Corp - 39
DLI Engr Corp - 40 Extracted Bearing Tones (3.1x)
Summary of Analysis Techniques Data Normalization Automated Spectral Peak Extraction Cepstrum Analysis Noise Floor Calculation Rule-Based Diagnostics Demodulation DLI Engr Corp - 41
High Noise Floor 120 VdB 110 100 90 80 70 60 0 2 4 6 8 10 12 DLI Engr Corp - 42 CPM ( X 1000 )
Summary of Analysis Techniques Data Normalization Automated Spectral Peak Extraction Cepstrum Analysis Noise Floor Calculation Rule-Based Diagnostics Demodulation DLI Engr Corp - 43
DLI Engr Corp - 44 Amplitude Modulated Wave Form and its Spectrum
Bearing Impact Faults High-Frequency Damped Oscillation Spall Acceleration Wave Form DLI Engr Corp - 45 Demodulaterd Waveform
DLI Engr Corp - 46 Demodulation Bearing Analysis
Bearing Faults DLI Engr Corp - 47 BPFO Frequency
DLI Engr Corp - 48 Demodulation Data: Bearing Tone at 3.1x
Amplitude Demodulation Early Warning of Bearing Wear Confirmation of Bearing Wear Better Information on Which Bearing is Defective DLI Engr Corp - 49
DLI Engr Corp - 50 Bearing Faults Typical Ranges
Diagnostic Report DLI Engr Corp - 51 FIRE PUMP #2 Acquired: 8/19/03 10:35:38 AM 1xM = 1191 RPM Averages: 3 RECOMMENDATIONS: MANDATORY: REPLACE MOTOR BEARINGS DIAGNOSES: EXTREME MOTOR BEARING WEAR 0.056 (+0.042) in/s at 3.11xM on 2A in low range 0.028 (+0.025) in/s at 6.22xM on 2A in low range 0.039 (+0.030) in/s at 9.33xM on 2R in low range 0.079 (+0.077) in/s at 9.33xM on 2T in low range 0.001 (+0.000) in/s at 24.8xM on 2A in high range 0.088 (+0.084) in/s at 3.11xM on 2R in low range 0.022 (+0.021) in/s at 15.5xM on 2R in high range 0.022 (+0.011) in/s at 12.5xM on 2R in high range 0.039 (+0.036) in/s at 3.11xM on 2T in low range 0.001 (+0.001) in/s noise floor 0.002 (+0.001) in/s noise floor 0.001 (+0.001) in/s noise floor MOTOR BALL BEARING DEMOD Bearing tone harmonics in demod spectrum with direct match between regular and demod spectrum in 2R 21 db peak at 9.33x on 2R
DLI Engr Corp - 52 Put it all together
Bearing The Movie DLI Engr Corp - 53 The life and times of a troubled bearing
Progression of Bearing Faults VdB Machine without Bearing Problems 120 1X 1 110 100 2X 90 3X 80 4X 70 60 DLI Engr Corp - 54 0 1 2 3 ORDERS 4 5 6
Progression of Bearing Faults VdB Slight Bearing Tones at 3.1X 120 1X 110 100 2X 90 3X 80 4X 70 60 DLI Engr Corp - 55 0 1 2 3 ORDERS 4 5 6
Progression of Bearing Faults VdB As defect worsens - 2nd harmonic rises 120 1X 110 100 2X 90 3X 80 4X 70 60 DLI Engr Corp - 56 0 1 2 3 ORDERS 4 5 6
Progression of Bearing Faults Increased machine looseness - 1X harmonics increase VdB 120 1X 110 2X 100 3X 4X 90 80 70 60 DLI Engr Corp - 57 0 1 2 3 ORDERS 4 10 12
Progression of Bearing Faults VdB 1X Sidebands around the Bearing Tone 120 1X 110 2X 100 3X 4X 90 80 70 60 DLI Engr Corp - 58 0 2 4 6 ORDERS 8 10 12
Progression of Bearing Faults VdB Haystack in Noise Floor appears as Wear Progresses 120 1X 110 2X 100 3X 4X 90 80 70 60 DLI Engr Corp - 59 0 2 4 6 ORDERS 8 10 12
Bearing Tone Sidebands Bearing Tone VdB 140 130 Sidebands spaced at FTF 120 110 100 90 80 70 DLI Engr Corp - 60 60 0 1 2 3 ORDERS 4 5 6
Progression of Bearing Faults VdB Entire Noise Floor rises in advanced stages 120 1X 110 2X 100 3X 4X 90 80 70 60 DLI Engr Corp - 61 0 2 4 6 ORDERS 8 10 12
Progression of Bearing Faults VdB Machine Failure 120 110 100 90 80 70 DLI Engr Corp - 62 60 0 2 4 6 ORDERS 8 10 12
DLI Engr Corp - 63 Summary of Analysis Techniques Data Normalization Automated Spectral Peak Extraction Cepstrum Analysis Noise Floor Calculation Rule-Based Diagnostics Demodulation
Key elements in a successful MCA Information, not Data Measurement Methodology Triaxial Data Collection with mounting pad (Complete data set & improved high frequency signal: Portable/Walk-around approach) Superior Data Screening (Statistic baseline in hi/low freq range & automated, narrow band data comparison) Analysis / Diagnostics / Prognosis Automated Diagnostic Report with severity, fault and prioritized repair recommendation (information NOT just data) Information Everywhere Distribution of Information DLI Engr Corp - 64 Simple, machine condition report/fault notification available via: Internet or automated pager, email, text message Delivering Machine Intelligence
Delivering Machine Intelligence DLI Engr Corp - 65 Visit our web site at: www.dliengineering.com