Presentation at Niagara Falls Vibration Institute Chapter January 20, 2005

Monitoring Gear Boxes with PeakVue Presentation at Niagara Falls Vibration Institute Chapter January 20, 2005 1

WHAT IS A STRESS WAVE? 2

Hertz Theory Prediction for Various Size Metal Balls 3

Frequencies Excited by 0.5, 1.0. And 1.5 D Balls Impacting CENT - OFF ROUTE EQUIPMENT OFF ROUTE - (25-Feb-99) Max Amp.84 Plot Scale 0.9 1.5" D Ball 25-Feb-99 14:54:52 RMS Acceleration in G-s 1.0" D Ball 25-Feb-99 14:54:02 0 0.5" D Ball 25-Feb-99 14:52:13 0 10 20 30 40 50 60 70 80 Frequency in khz 4

Impacting and Friction: 1.0 + D 0.024 0.020 Roller CENT - OFF ROUTE EQUIPMENT OFF ROUTE - Analyze Spectrum 28-Feb-01 15:07:31 RMS =.0892 LOAD = 100.0 RPM = 696. (11.60 Hz) RMS Acceleration in G-s 0.016 0.012 0.008 0.004 0 0 10000 20000 30000 40000 Frequency in Hz Label: OFFROUTE-A-1 / 5

Analysis of Stress Waves Capture with accelerometer High-pass filter Capture time block of data (peak values) a) Spectral Analysis b) Autocorrelation analysis 6

Example Time Waveform Select F max Delta t = 1/(2.56 F max ) Sequentially insert in each Delta t the Peak Value observed over that time increment 7

PeakVue Waveform Indicates Defective Rolling Elements (Rollers pass in and out of load zone at rate of Cage Freq.) 8

PeakVue Spectrum Derived from PeakVue Waveform (Cage Freq. = 3.43 Hz; BSF = 40.6 Hz) 9

Autocorrelation Coefficient Function Identifies Dominant Impact Sources in PeakVue Data 10

11 ( ) ( ) ( ) ( ) 2 1, ; 1, ; 0 1 2 / 1 N j t j N i t i t t x t x A A j i N i j i i j = = = = + = = τ τ τ Computation of Autocorrelation

Measurement Setup Parameters F HP F max Select F max Based on Fault Frequencies Bearings: F max > 4 BPFI Gearing: F max > 2 GMF Select Resolution (# Lines) Based on Lowest Fault Frequency Bearings: Cage Gearing: Slowest shaft for gear pair in Mesh 12

Measurement Setup Parameters (cont.) Cage - requires 12+ shaft revs # Revs = F m # lines in orders Shaft - Requires 5+ shaft revs F HP (High-Pass Filter) Same (highest) over a machine (structure with continuous housing). F HP greatest for bearings or gears on machine F max can be varied, but same F HP must be used on all points on component (i.e., throughout Gearbox) 13

Guidelines for setting Pk-Pk PeakVue Time Waveform Alert Alarm Levels for an inner race fault (Set Fault Alarm = 2 X Alert 4.743 Alarm) 3.000 3.000 Acceleration in g's (p-p) 10.000 Recommended P-P Time Waveform Alert Limits 1.000 0.577 0.100 0.103 1 10 100 1000 10000 Speed (RPM) RPM 0.75 g's = 900 3 for RPM < 900 g s = 3, for 900 < RPM 4000, RPM 0.5 g's = 4000 3 for 4000 < RPM 10000, g s = 5, for RPM > 10000, 14

Gear Box Case Study # 1 A) Cracked Tooth on post rebuild gear box B) Cracked Tooth on Precision Tension Bridle 15

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Fault under Meas Point G5 17

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Cracked Tooth Highlighted 19

Cracked Teeth in Precision Tension Bridle GearBox - Based on Pk-Pk Level of 41 g s in TWF - Pronounced Impact Pulses in TWF (2/Rev) - No Real Indication of Problem in Vibration Data 20

Plan view of precision tension bridle gearbox (single speed reduction with two output shafts) 21

Velocity spectral and acceleration waveform data (Fmax=2000 Hz) from the bearing on the input shaft of the precision tension bridle SM - Precision Tension Bridle PT BRIDLE -GV3 0.04 GM 1 gearbox PK Velocity in In/Sec 0.03 0.02 0.01 GM 2 201.59 350.68 ROUTE SPECTRUM 14-Apr-97 07:59:17 OVERALL=.0812 V-DG PK =.0808 LOAD = 100.0 RPM = 526. RPS = 8.77 Acceleration in G-s 0 2.0 1.5 1.0 0.5 0-0.5-1.0-1.5-2.0-2.5 0 500 1000 1500 2000 Frequency in Hz 0 50 100 150 200 Time in msecs WAVEFORM DISPLAY 14-Apr-97 07:59:17 RMS =.3687 PK(+) = 1.59 PK(-) = 1.86 CRESTF= 5.06 Freq: Ordr: Spec: 351.25 40.07.02589 22

SM - Precision Tension Bridle PT BRIDLE -GV3 5 ANALYZE SPECTRUM 14-Apr-97 08:28:16 shaft 4 of the precision tension bridle PeakVue gearbox (Filtr- HP 500 Hz) RMS = 6.50 LOAD = 100.0 3 RPM = 216. RPS = 3.60 RMS Acceleration in G-s PeakVue spectral and waveform data (F max =200 Hz) from the bearing on the input 2 1 Acceleration in G-s 0 0 50 100 150 200 Frequency in Hz 40 30 20 10 0 WAVEFORM DISPLAY 14-Apr-97 08:28:16 RMS = 7.16 PK(+) = 36.54 PK(-) = 4.82 CRESTF= 5.10-10 0 0.5 1.0 1.5 2.0 Time in Seconds Freq: Ordr: Spec: 3.625 1.008 3.288 23

PeakVue spectral and (Fmax=100 Hz but with a 5000 Hz HP filter) from the bearing on the input shaft of the precision tension bridle gearbox GM 2 24

Case Study # 2 Gearbox Eccentric gear on post rebuild gear box 25

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Defective Gear Placed in Separate Gear Box 28

Gear Box Case study #3 Worn spline on post rebuild gear box 29

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Bearing-Outer Race Case Study #4 BPFO in Pinion Stand Gearbox Speed of shaft=360 RPM Peak g-level=37 g s Fault=6.3 g s 33

Velocity spectral and acceleration waveform data (Fmax=800 Hz) from the bearing on the input shaft of the gearbox (Sept 15) 1X GMF Velocity BPFO 2X GMF 4.13 g s 34

Peakvue spectral and waveform data (Fmax=1000 Hz) from the bearing on the input shaft of the gearbox (Sept 15) BPFO = 64.38 Hz = 10.75 X RPM PeakVue 1/BPFO 36.96 g 35

Peakvue spectral and waveform data (Fmax=1000 Hz) from the bearing on the input shaft of the gearbox before and after bearing replacement BPFO PeakVue Before Bearing Replacement PeakVue After Bearing Replacement 36

Closeup picture of the outer race of the defective bearing showing significant spalling over an area of 5 in. x 5 in. 37

Bearing Outer Race Case Study #5 BPFO Early stage fatiguing Shaft speed=650 RPM Alert=4.7 g s 38

A l e r t = 4. 7 RMS Acceleration in G-s g s Acceleration in G-s Alert=4.7 g s 0.07 0.06 0.05 0.04 0.03 0.02 0.01 0 1.4 1.2 1.0 0.8 0.6 0.4 0.2 WDT - GBOX GBOX -P4 Measurement Pt4 C C C C C C C C 0 10 20 30 40 50 Frequency in Orders Routine Spectrum 03-Feb-03 09:04:17 (PkVue-HP 2000 Hz) RMS =.1353 LOAD = 100.0 RPM = 538. (8.97 Hz) >skf nj2332ec C=BPFO Routine Waveform 03-Feb-03 09:04:17 (PkVue-HP 2000 Hz) RMS =.2671 PK(+) = 1.15 CRESTF= 4.32 0 0 3 6 9 12 15 18 Revolution Number Ordr: Freq: Spec: 5.253 47.12.06017 39

Impacting Sporadic WDT - GBOX GBOX -P4 Measurement Pt4.33.0963 02-Feb-03 18:30 Acceleration in G-s.92.0899.93.0959 02-Feb-03 16:22 02-Feb-03 15:17 1.15.0892 03-Feb-03 09:04 0 3 6 9 12 15 18 Revolution Number 40

Bearing (Inner Race) Case Study #6 BPFI on bearing on output shaft Severity ascertained from trending 41

Trend (2 years) of the maximum peak amplitude (g s) from the Peakvue waveform and a Peakvue spectrum on May 25 BPFI with 1X RPM sidebands 1X RPM 2X BPFI 42

Trend (2 years) of the bearing frequency band from the velocity spectrum and a Velocity spectrum on May 25 2X GMF Velocity GMF No indication of a bearing fault 43

Picture of the defective bearing with a significant inner race defect identified by Peakvue trends 44

PeakVue Trend Before & After Bearing was Replaced (Trend of Digital Overall) RMS Acceleration in G-s 0.6 0.5 0.4 0.3 0.2 RFPD - HOT MILL-F5 PINION STAND 200 HMF5PINSTD-P4H BOT BRG OUTPUT SIDE HORIZ.PK-VUE 10/19/99 02/01/00 05/18/00 06/28/00 Trend Display of OVERALL VALUE -- Baseline -- Value:.04003 Date: 01/07/99 0.1 11/06/98 03/25/99 08/17/00 0 0 100 200 300 400 500 600 700 800 Days: 07/31/98 To 08/17/00 Label: Trend After Bearing Replaced Date: Time: Ampl: 08/17/00 13:03:27.01550 45

Bearing Inner Race Case Study # 7 BPFI (mechanical plus lubrication) 46

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Data acquired outer bearing re input RMS Acceleration in G-s 0.18 0.15 0.12 0.09 0.06 0.03 14.87 IGB - Roller Mill Peak Vue RM-PV -G2 Gearbox Point 2 129.49 BPFI 258.98 388.47 Route Spectrum 09-Jan-02 12:43:10 (PkVue-HP 1000 Hz) OVERALL=.4408 A-DG RMS =.4387 LOAD = 100.0 RPM = 892. (14.87 Hz) 0 Acceleration in G-s 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 50 100 150 200 250 300 350 400 Frequency in Hz Route Waveform 09-Jan-02 12:43:10 (PkVue-HP 1000 Hz) RMS =.8999 PK(+) = 3.58 CRESTF= 3.94 0 0 200 400 600 800 1000 Time in msecs Freq: Ordr: Spec: Dfrq: 114.63 7.709.09612 14.86 48

Typical BPFI pattern in Autocorrelation 1.0 0.5 IGB - Roller Mill Peak Vue RM-PV -G2 Gearbox Point 2 Route ACorr(Wf) 09-Jan-02 12:43:10 (PkVue-HP 1000 Hz) RMS =.0860 LOAD = 100.0 RPM = 892. (14.87 Hz) PK(+) =.4534 PK(-) =.1173 CRESTF= 5.27 Correlation Factor 0-0.5-1.0 0 100 200 300 400 500 600 Time in msecs 49

Trended Peak g-level from G2 Peak g Trend Data For Measurement Point G2 90 80 70 g's Peak 60 50 40 Peak G's Alert Fault 30 20 10 0 0 50 100 150 200 250 300 350 Days 50

51 g s on Point G2 on February 6, 2002 RMS Acceleration in G-s 7 6 5 4 3 2 1 14.89 IGB - Roller Mill Peak Vue RM-PV -G2 Gearbox Point 2 129.67 BPFI 259.35 389.02 Route Spectrum 06-Feb-02 12:43:59 (PkVue-HP 1000 Hz) OVERALL= 8.28 A-DG RMS = 8.28 LOAD = 100.0 RPM = 893. (14.89 Hz) 0 Acceleration in G-s 60 50 40 30 20 10 0 50 100 150 200 250 300 350 400 Frequency in Hz Route Waveform 06-Feb-02 12:43:59 (PkVue-HP 1000 Hz) RMS = 12.87 PK(+) = 51.09 CRESTF= 3.92 0 0 200 400 600 800 1000 Time in msecs Freq: Ordr: Spec: Dfrq: 114.78 7.709 1.034 14.89 51

25 g s on Point G1 on February 6, 2002. RMS Acceleration in G-s 3.2 2.8 2.4 2.0 1.6 1.2 0.8 0.4 14.89 IGB - Roller Mill Peak Vue RM-PV -G1 Gearbox Point 1 129.68 259.36 389.05 Route Spectrum 06-Feb-02 12:43:19 (PkVue-HP 1000 Hz) OVERALL= 3.76 A-DG RMS = 3.74 LOAD = 100.0 RPM = 893. (14.89 Hz) 0 Acceleration in G-s 24 20 16 12 8 4 0 50 100 150 200 250 300 350 400 Frequency in Hz Route Waveform 06-Feb-02 12:43:19 (PkVue-HP 1000 Hz) RMS = 6.71 PK(+) = 24.21 CRESTF= 3.62 0 0 200 400 600 800 1000 Time in msecs Freq: Ordr: Spec: Dfrq: 114.80 7.709.475 14.88 52

Note metal removal on inner race downstream of fault 53

Gear Fault in Planetary Gear Planetary Gearbox Carrier turning at approximately 20 RPM 54

Dominant activity at 3x: 0.34 g s on October 23, 2002 RMS Acceleration in G-s 0.020 0.015 0.010 0.005 GBOX WDT - GBOX -P2A Measurement Pt2A Routine Spectrum 23-Oct-02 13:16:58 (PkVue-HP 2000 Hz) RMS =.0401 LOAD = 100.0 RPM = 20. (.33 Hz) 0 Acceleration in G-s 0.40 0.32 0.24 0.16 0.08 0 10 20 30 40 50 Frequency in Hz Routine Waveform 23-Oct-02 13:16:58 (PkVue-HP 2000 Hz) RMS =.1352 PK(+) =.3424 CRESTF= 2.53 DCoff =.2176 0 0 4 8 12 16 20 24 28 32 Time in Seconds Freq: 1.000 Ordr: 3.006 Spec:.01473 55

Autocorrelation on October 23, 2002 1.0 GBOX WDT - GBOX -P2A Measurement Pt2A Routine ACorr(Wf) 23-Oct-02 13:16:58 (PkVue-HP 2000 Hz) 0.5 RMS =.1256 LOAD = 100.0 RPM = 20. (.33 Hz) Correlation Factor 0 PK(+) =.5790 PK(-) =.2883 CRESTF= 4.61-0.5-1.0 0 4 8 12 16 Time in Seconds 56

Dominate activity at 1x: 2.1 g s on December 30, 2002 RMS Acceleration in G-s 0.07 0.06 0.05 0.04 0.03 0.02 0.01 GBOX WDT - GBOX -P2A Measurement Pt2A Routine Spectrum 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS =.1177 LOAD = 100.0 RPM = 20. (.33 Hz) 0 Acceleration in G-s 2.4 2.0 1.6 1.2 0.8 0.4 0 4 8 12 16 Frequency in Orders Routine Waveform 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS =.2261 PK(+) = 2.10 CRESTF= 9.27 DCoff =.2427 0 0 10 20 30 40 50 60 70 80 Time in Seconds Ordr: 1.010 Freq:.338 Spec:.04590 57

Autocorrelation on December 30, 2002 1.0 0.5 Dominate activity at 2.47 orders WDT - GBOX GBOX -P2A Measurement Pt2A Dela orders=2.472 Routine ACorr(Wf) 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS =.1682 LOAD = 100.0 RPM = 20. (.33 Hz) Correlation Factor 0 PK(+) =.8097 PK(-) =.2306 CRESTF= 4.81-0.5-1.0 0 5 10 15 20 25 30 35 40 Time in Seconds Time: Ampl: Dtim: Freq: 16.94.220 1.209.827 58

Activity Highlighted at 2.47 Orders RMS Acceleration in G-s 0.07 0.06 0.05 0.04 0.03 0.02 0.01 WDT - GBOX GBOX -P2A Measurement Pt2A 89/36=2.472 Routine Spectrum 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS =.1177 LOAD = 100.0 RPM = 20. (.33 Hz) 0 Acceleration in G-s 2.4 2.0 1.6 1.2 0.8 0.4 0 4 8 12 16 Frequency in Orders Routine Waveform 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS =.2261 PK(+) = 2.10 CRESTF= 9.27 DCoff =.2427 0 0 10 20 30 40 50 60 70 80 Time in Seconds Ordr: 2.472 Freq:.826 Spec:.04985 59

2.47 activity gone on February Dominate activity at 3x: 0.75 g s 3, 2003 RMS Acceleration in G-s 0.016 0.012 0.008 0.004 2.47 3.00 6.00 9.00 GBOX 12.00 WDT - GBOX -P2A Measurement Pt2A 15.00 18.00 21.00 24.00 27.00 Routine Spectrum 02-Feb-03 15:16:20 (PkVue-HP 2000 Hz) RMS =.0312 LOAD = 100.0 RPM = 20. (.33 Hz) Acceleration in G-s 0 0.8 0.7 0.6 0.5 0.4 0.3 0 5 10 15 20 25 30 Frequency in Orders Routine Waveform 02-Feb-03 15:16:20 (PkVue-HP 2000 Hz) RMS =.3252 PK(+) =.7509 CRESTF= 2.31 0.2 0 3 6 9 12 15 18 21 24 27 Revolution Number Ordr: Freq: Spec: 2.471.825.00484 60