1
Monitoring Gear Boxes with PeakVue
Presentation at Niagara Falls Vibration Institute Chapter
January 20, 2005
2
WHAT IS A STRESS WAVE?WHAT IS A STRESS WAVE?
3
HertzHertz TheoryTheory Prediction for Various Size Prediction for Various Size Metal BallsMetal Balls
4
Frequencies Excited by 0.5”, 1.0”. And 1.5” D Balls Impacting
RM
S A
ccel
erat
ion
in G
-s
Frequency in kHz
CENT - OFF ROUTE EQUIPMENTOFF ROUTE - (25-Feb-99)
0 10 20 30 40 50 60 70 80
Max Amp .84
Plot Scale
0
0.9
14:52:1325-Feb-99
14:54:0225-Feb-99
14:54:5225-Feb-99
1.5" D Ball
1.0" D Ball
0.5" D Ball
5
Impacting and Friction: 1.0 +” D Roller
CENT - OFF ROUTE EQUIPMENTOFF ROUTE -
Label: OFFROUTE-A-1 /
Analyze Spectrum 28-Feb-01 15:07:31
RMS = .0892 LOAD = 100.0 RPM = 696. (11.60 Hz)
0 10000 20000 30000 40000
0
0.004
0.008
0.012
0.016
0.020
0.024
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
6
• Capture with accelerometer• High-pass filter• Capture time block of data
(peak values)a) Spectral Analysisb) Autocorrelation analysis
Analysis of Stress WavesAnalysis of Stress Waves
7
Example Time Waveform
Select Fmax
Delta t = 1/(2.56 × Fmax)
Sequentially insert in each Delta t the Peak Value observed over that time increment
8
PeakVue Waveform Indicates Defective Rolling ElementsPeakVue Waveform Indicates Defective Rolling Elements(Rollers pass in and out of load zone at rate of Cage Freq.)(Rollers pass in and out of load zone at rate of Cage Freq.)
9
PeakVue Spectrum Derived from PeakVue Waveform PeakVue Spectrum Derived from PeakVue Waveform (Cage Freq. = 3.43 Hz; BSF = 40.6 Hz)(Cage Freq. = 3.43 Hz; BSF = 40.6 Hz)
10
Autocorrelation Coefficient Function Identifies Autocorrelation Coefficient Function Identifies Dominant Impact Sources in PeakVue DataDominant Impact Sources in PeakVue Data
11
( ) ( ) ( ) ( )
2,1;
,1;
01 2/
1
Njtj
Nitit
txtxA
A
j
i
N
ijiij
=∆=
=∆=
∑ +==
τ
ττ
Computation of Autocorrelation
12
FHP ≥ Fmax
• Select Fmax Based on Fault FrequenciesBearings: Fmax > 4 × BPFIGearing: Fmax > 2 × GMF
• Select Resolution (# Lines) Based on Lowest Fault FrequencyBearings: CageGearing: Slowest shaft for gear pair in Mesh
Measurement Setup Parameters
Measurement Setup Parameters
13
• Cage - requires 12+ shaft revs
Measurement Setup Parameters (cont.)
Measurement Setup Parameters (cont.)
ordersinline#
Revs#mF
s=
• Shaft - Requires 5+ shaft revs• FHP (High-Pass Filter)
– Same (highest) over a machine (structure with continuous housing).
– FHP greatest for bearings or gears on machine– Fmax can be varied, but same FHP must be used
on all points on component (i.e., throughout Gearbox)
14
Guidelines for setting Pk-Pk PeakVue Time Waveform
Alert Alarm Levels for an inner race fault
(Set Fault Alarm = 2 X Alert Alarm)
Guidelines for setting Pk-Pk PeakVue Time Waveform
Alert Alarm Levels for an inner race fault
(Set Fault Alarm = 2 X Alert Alarm)
3 900
RPM 0.75
×
=g's for RPM < 900
g’s = 3 , for 900 < RPM ≤ 4000 ,
3 4000RPM 0.5
×
=g's for 4000 < RPM ≤ 10000 ,
g’s = 5 , for RPM > 10000 ,
Recom m ended P-P Tim e Waveform Aler t Lim its
0.577
4.743
3.000 3.000
0.1030.100
1.000
10.000
1 10 100 1000 10000
Speed (RPM)
Acc
eler
atio
n in
g's
(p-p
)
15
Gear Box
• Case Study # 1– A) Cracked Tooth on post rebuild gear
box– B) Cracked Tooth on Precision Tension
Bridle
16
17
Fault under Meas Point G5
18
19
Cracked Tooth Highlighted
20
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
21
Plan view of precision tension bridle gearbox (single speed reduction with
two output shafts)
22
WAVEFORM DISPLAY 14-Apr-97 07:59:17 RMS = .3687 PK(+) = 1.59 PK(-) = 1.86 CRESTF= 5.06
0 50 100 150 200-2.5
-2.0
-1.5
-1.0
-0.5
0
0.5
1.0
1.52.0
Time in mSecs
Acc
eler
atio
n in
G-s
SM - Precision Tension BridlePT BRIDLE -GV3
ROUTE SPECTRUM 14-Apr-97 07:59:17 OVERALL= .0812 V-DG PK = .0808 LOAD = 100.0 RPM = 526. RPS = 8.77
0 500 1000 1500 20000
0.01
0.02
0.03
0.04
Frequency in Hz
PK
Vel
ocity
in In
/Sec
201.
59
350.
68
Freq: Ordr: Spec:
351.25 40.07 .02589
GM 2
GM 1
Velocity spectral and acceleration waveform data (Fmax=2000 Hz) from the bearing on the
input shaft of the precision tension bridle gearbox
23
WAVEFORM DISPLAY 14-Apr-97 08:28:16 RMS = 7.16 PK(+) = 36.54 PK(-) = 4.82 CRESTF= 5.10
0 0.5 1.0 1.5 2.0-10
0
10
20
30
40
Time in Seconds
Acc
eler
atio
n in
G-s
SM - Precision Tension BridlePT BRIDLE -GV3
ANALYZE SPECTRUM 14-Apr-97 08:28:16 (Filtr- HP 500 Hz) RMS = 6.50 LOAD = 100.0 RPM = 216. RPS = 3.60
0 50 100 150 2000
1
2
3
4
5
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
Freq: Ordr: Spec:
3.625 1.008 3.288
PeakVue
PeakVue spectral and waveform data (Fmax=200 Hz) from the bearing on the input shaft of the precision tension bridle gearbox
24
GM2
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
25
Gearbox• Case Study # 2
– Eccentric gear on post rebuild gear box
26
27
28
Defective Gear Placed in Separate Gear Box
29
Gear Box
• Case study #3– Worn spline on post rebuild gear box
30
31
32
33
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
34
4.13 g’s
1X GMF
2X GMF
Velocity
BPFO
Velocity spectral and acceleration waveform data (Fmax=800 Hz) from the bearing on the input shaft of the
gearbox (Sept 15)
35
BPFO = 64.38 Hz = 10.75 X RPM
1/BPFO
36.96 g
PeakVue
Peakvue spectral and waveform data (Fmax=1000 Hz) from the bearing on the
input shaft of the gearbox (Sept 15)
36
PeakVue Before Bearing Replacement
PeakVue After Bearing Replacement
BPFO
Peakvue spectral and waveform data (Fmax=1000 Hz) from the bearing on the input shaft of the gearbox before and after
bearing replacement
37
Closeup picture of the outer race of the defective bearing showing significant spalling over an area of 5 in. x 5 in.
38
Bearing Outer Race
• Case Study #5 BPFO– Early stage fatiguing – Shaft speed=650 RPM– Alert=4.7 g’s
39
Routine Waveform 03-Feb-03 09:04:17 (PkVue-HP 2000 Hz) RMS = .2671 PK(+) = 1.15 CRESTF= 4.32
0 3 6 9 12 15 18
0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Revolution Number
Acc
eler
atio
n in
G-s
WDT - GBOXGBOX -P4 Measurement Pt4
Routine Spectrum 03-Feb-03 09:04:17 (PkVue-HP 2000 Hz) RMS = .1353 LOAD = 100.0 RPM = 538. (8.97 Hz)
0 10 20 30 40 50
0
0.01
0.02
0.03
0.04
0.05
0.06
0.07
Frequency in Orders
RM
S A
ccel
erat
ion
in G
-s
Ordr: Freq: Spec:
5.253 47.12 .06017
>skf nj2332EC C=BPFO
C C C C C C C C
Alert=4.7
g’s
Alert=4.7 g’s
40
WDT - GBOXGBOX -P4 Measurement Pt4
Revolution Number
Acc
eler
atio
n in
G-s
0 3 6 9 12 15 18
1.15 .0892 03-Feb-03 09:04
.93 .0959 02-Feb-03 15:17
.92 .0899 02-Feb-03 16:22
.33 .0963 02-Feb-03 18:30
Impacting Sporadic
41
Bearing (Inner Race)
• Case Study #6– BPFI on bearing on output shaft– Severity ascertained from trending
42
BPFI with 1X RPM sidebands
2X BPFI1X RPM
Trend (2 years) of the maximum peak amplitude (g’s) from the Peakvue
waveform and a Peakvue spectrum on May 25
43
No indication of a bearing fault
2X GMFVelocity
GMF
Trend (2 years) of the bearing frequency band from the velocity spectrum and a
Velocity spectrum on May 25
44
Picture of the defective bearing with a significant inner race defect identified by
Peakvue trends
45
RFPD - HOT MILL-F5 PINION STAND 200HMF5PINSTD-P4H BOT BRG OUTPUT SIDE HORIZ.PK-VUE
Label: Trend After Bearing Replaced
Trend Display of OVERALL VALUE
-- Baseline -- Value: .04003 Date: 01/07/99
0 100 200 300 400 500 600 700 800
0
0.1
0.2
0.3
0.4
0.5
0.6
Days: 07/31/98 To 08/17/00
RM
S A
ccel
erat
ion
in G
-s
11/0
6/98
03/2
5/99
10/1
9/99
02/0
1/00
05/1
8/00
08/1
7/00
06/2
8/00
Date: Time: Ampl:
08/17/00 13:03:27 .01550
PeakVue Trend Before & After Bearing was ReplacedPeakVue Trend Before & After Bearing was Replaced(Trend of Digital Overall)(Trend of Digital Overall)
46
Bearing Inner Race• Case Study # 7
– BPFI (mechanical plus lubrication)
47
48
Route Waveform 09-Jan-02 12:43:10 (PkVue-HP 1000 Hz) RMS = .8999 PK(+) = 3.58 CRESTF= 3.94
0 200 400 600 800 1000
0
0.5
1.0
1.5
2.0
2.5
3.0
3.54.0
Time in mSecs
Acc
eler
atio
n in
G-s
IGB - Roller Mill Peak VueRM-PV -G2 Gearbox Point 2
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 50 100 150 200 250 300 350 400
0
0.03
0.06
0.09
0.12
0.15
0.18
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
14.8
7
129.
49
258.
98
388.
47
Freq: Ordr: Spec: Dfrq:
114.63 7.709 .09612 14.86
BPFI
Data acquired outer bearing re input
49
IGB - Roller Mill Peak VueRM-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
0 100 200 300 400 500 600
-1.0
-0.5
0
0.5
1.0
Time in mSecs
Cor
rela
tion
Fact
or
Typical BPFI pattern in Autocorrelation
50
Trended Peak g-level from G2Peak g Trend Data For Measurement Point G2
0
10
20
30
40
50
60
70
80
90
0 50 100 150 200 250 300 350
Days
g's
Pea
k
Peak G's
Alert
Fault
51
Route Waveform 06-Feb-02 12:43:59 (PkVue-HP 1000 Hz) RMS = 12.87 PK(+) = 51.09 CRESTF= 3.92
0 200 400 600 800 1000
0
10
20
30
40
50
60
Time in mSecs
Acc
eler
atio
n in
G-s
IGB - Roller Mill Peak VueRM-PV -G2 Gearbox Point 2
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 50 100 150 200 250 300 350 400
0
1
2
3
4
5
6
7
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
14.8
9
129.
67
259.
35
389.
02
Freq: Ordr: Spec: Dfrq:
114.78 7.709 1.034 14.89
BPFI
51 g’s on Point G2 on February 6, 2002
52
Route Waveform 06-Feb-02 12:43:19 (PkVue-HP 1000 Hz) RMS = 6.71 PK(+) = 24.21 CRESTF= 3.62
0 200 400 600 800 1000
0
4
8
12
16
20
24
Time in mSecs
Acc
eler
atio
n in
G-s
IGB - Roller Mill Peak VueRM-PV -G1 Gearbox Point 1
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 50 100 150 200 250 300 350 400
0
0.4
0.8
1.2
1.6
2.0
2.4
2.83.2
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
14.8
9
129.
68
259.
36
389.
05
Freq: Ordr: Spec: Dfrq:
114.80 7.709 .475 14.88
25 g’s on Point G1 on February 6, 2002.
53
Note metal removal on inner race downstream of fault
54
Gear Fault in Planetary Gear
• Planetary Gearbox
• Carrier turning at approximately 20 RPM
55
Routine Waveform 23-Oct-02 13:16:58 (PkVue-HP 2000 Hz) RMS = .1352 PK(+) = .3424 CRESTF= 2.53 DCoff = .2176
0 4 8 12 16 20 24 28 32
0
0.08
0.16
0.24
0.32
0.40
Time in Seconds
Acc
eler
atio
n in
G-s
WDT - GBOXGBOX -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 10 20 30 40 50
0
0.005
0.010
0.015
0.020
Frequency in Hz
RM
S A
ccel
erat
ion
in G
-s
Freq: Ordr: Spec:
1.000 3.006 .01473
Dominant activity at 3x: 0.34 g’s on Dominant activity at 3x: 0.34 g’s on October 23, 2002October 23, 2002
56
WDT - GBOXGBOX -P2A Measurement Pt2A
Routine ACorr(Wf) 23-Oct-02 13:16:58 (PkVue-HP 2000 Hz)
RMS = .1256 LOAD = 100.0 RPM = 20. (.33 Hz)
PK(+) = .5790 PK(-) = .2883 CRESTF= 4.61
0 4 8 12 16
-1.0
-0.5
0
0.5
1.0
Time in Seconds
Cor
rela
tion
Fact
orAutocorrelation on October 23, 2002
57
Routine Waveform 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS = .2261 PK(+) = 2.10 CRESTF= 9.27 DCoff = .2427
0 10 20 30 40 50 60 70 80
0
0.4
0.8
1.2
1.6
2.0
2.4
Time in Seconds
Acc
eler
atio
n in
G-s
WDT - GBOXGBOX -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 4 8 12 16
0
0.01
0.02
0.03
0.04
0.05
0.060.07
Frequency in Orders
RM
S A
ccel
erat
ion
in G
-s
Ordr: Freq: Spec:
1.010 .338 .04590
Dominate activity at 1x: 2.1 g’s on December 30, 2002
58
WDT - GBOXGBOX -P2A Measurement Pt2A
Routine ACorr(Wf) 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz)
RMS = .1682 LOAD = 100.0 RPM = 20. (.33 Hz)
PK(+) = .8097 PK(-) = .2306 CRESTF= 4.81
0 5 10 15 20 25 30 35 40
-1.0
-0.5
0
0.5
1.0
Time in Seconds
Cor
rela
tion
Fact
or
Time: Ampl: Dtim: Freq:
16.94 .220 1.209 .827
Dela orders=2.472
Autocorrelation on December 30, 2002
Dominate activity at 2.47 orders
59
Routine Waveform 30-Dec-02 12:46:34 (PkVue-HP 2000 Hz) RMS = .2261 PK(+) = 2.10 CRESTF= 9.27 DCoff = .2427
0 10 20 30 40 50 60 70 80
0
0.4
0.8
1.2
1.6
2.0
2.4
Time in Seconds
Acc
eler
atio
n in
G-s
WDT - GBOXGBOX -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 4 8 12 16
0
0.01
0.02
0.03
0.04
0.05
0.060.07
Frequency in Orders
RM
S A
ccel
erat
ion
in G
-s
Ordr: Freq: Spec:
2.472 .826 .04985
89/36=2.472
Activity Highlighted at 2.47 Orders
60
2.47 activity gone on February 3, 2003
Routine Waveform 02-Feb-03 15:16:20 (PkVue-HP 2000 Hz) RMS = .3252 PK(+) = .7509 CRESTF= 2.31
0 3 6 9 12 15 18 21 24 27
0.2
0.3
0.4
0.5
0.6
0.7
0.8
Revolution Number
Acc
eler
atio
n in
G-s
WDT - GBOXGBOX -P2A Measurement Pt2A
Routine Spectrum 02-Feb-03 15:16:20 (PkVue-HP 2000 Hz) RMS = .0312 LOAD = 100.0 RPM = 20. (.33 Hz)
0 5 10 15 20 25 30
0
0.004
0.008
0.012
0.016
Frequency in Orders
RM
S A
ccel
erat
ion
in G
-s
2.47
3.00
6.00
9.00
12.0
0
15.0
0
18.0
0
21.0
0
24.0
0
27.0
0
Ordr: Freq: Spec:
2.471 .825 .00484
Dominate activity at 3x: 0.75 g’s