Vibration Analysis by SKF Bearings.pdf

15-07-08 ©SKF
SKF Reliability Systems – Indonesia
Jaka Rusdianto
Slide 2
Vibration Analysis
Conducted by:
Anis Lutfi
Condition Monitoring, SKF Reliability
Systems PT. Skefindo Primatama -
INDONESIA

15-07-08 ©SKF Slide 3
SKF Reliability Systems – Asia Pacific
Condition Monitoring Products
1
SKF PLATFORM
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Slide 4
15-07-08 ©SKF
SKF GROUP
FACTORY UNIT
• 80 Factories
• 1 in Indonesia
• 45,000 employees
• ISO 14001
SALES UNIT
SKF SALES ASIA PACIFIC
SKF VIETNAM
SKF THAILAND
SKF TAIWAN
SKF KOREA
SKF PHILIPINA
SKF MALAYSIA
SKF SINGAPORE
SKF INDONESIA (PT.SKEFINDO) etc.
• 130 COUNTRY
• 7,000 DISTRIBUTOR

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Slide 5
15-07-08 ©SKF
SKF Network

15-07-08 ©SKF Slide 6
SKF R
eliability Systems – Indonesia
Jaka Rusdianto
2
MAINTENANCE PILOSOPHY
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Slide 7
15-07-08 ©SKF
The evolution continues…
Not to fix failed machinery, but to prevent machinery failing.
• To maximize productivity.
• To ensure machinery operates satisfactorily and
continuously for its rated life - or longer.
• To provide the highest machine availability, with minimum
downtime due to maintenance and service.
• To continuously improve the production process.
• To optimize machine performance.
• Smoother, efficient running machinery costs less to
operate, and produces a higher quality product.
• To provide a safe environment.
Slide 7

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Slide 8
15-07-08 ©SKF
Cost of Maintenance
$17–18 US
$11–13 US
$7–9 US
Type of Maintenance Program
Run to
Failure
Maintenance
Predictive
Maintenance
Preventive
Maintenance
Cost of
Maintenance
US $/HP/Year
Customer : Cevron Oil USA

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Slide 9
15-07-08 ©SKF
How Do Predictive
Maintenance Programs W
ork?

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Slide 10
15-07-08 ©SKF
The Predictive Maintenance Cycle
Measurement
exceeds
alarm limit
Periodic
Monitoring
Analyze
problem
Repair
Equipment
Schedule
repair(s)
No
Yes
Increase meas. intervals

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Slide 11
15-07-08 ©SKF
W
orkFlow
W
orkFlow
PRISM4
MICROLOG
ROUTE
SCHEDULE
(CMMS)
WORK REQUEST
(CMMS)
C.MONITORING
PLAN
DAILY REPORT
MONTHLY
REPORT
DATA ANALYSIS
RELIABILITY
(Keandalan)
MAINTENANCE
(Perawatan)
PRODUCTION
(Produksi)
Management

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Slide 12
15-07-08 ©SKF
How are Measurements Performed?
Sensors ... Sense and Convert Mechanical Energy Into An
Electrical Signal

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Slide 13
15-07-08 ©SKF
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Slide 14
15-07-08 ©SKF
Predictive Maintenance
Measurements
Vibration
Temperature
Lube Oil
Process
–Pressure
–Flow
–Speed

15-07-08 ©SKF Slide 15
3
Basic Vibration Philosophy
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Slide 16
15-07-08 ©SKF
Measuring Vibration
Vibration is
considered one of
the most effective
measurements for
monitoring the
condition of
rotating machinery

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Slide 17
15-07-08 ©SKF
Measurable Vibration Characteristics
Frequency - W
hat is vibrating?
Amplitude - How much is it
vibrating?
Phase Angle - How is it vibrating?

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Slide 18
15-07-08 ©SKF
Vibration Frequency
Measurements & Units
• RPM(Revolutions PerMinute)
• CPM(Cycles PerMinute)
• CPS/
Hz (Cycles PerSecond/
Hertz)
• Orders of Running Speed (how many
times event occurs pershaft revolution)

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Slide 19
15-07-08 ©SKF
Vibration Amplitude
Measurements & Units
Displacement (Distance)
Mils orMicrons
Velocity (Speed - Rate of change of displcmt)
In./
Sec. ormm/
Sec.
Acceleration (Rate of change of velocity)
G’s - In./
Sec.2
orMeter/
Sec.2

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Slide 20
15-07-08 ©SKF
Amplitude vs. Frequency
W
hen analyzing vibration we lookat two components of
the vibration signal, its amplitude and its frequency.
 Vibration amplitude indicates the severity of the
problem.
 Vibration frequency indicates the source of the
problem.

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Slide 21
15-07-08 ©SKF
Displacement Probe/
Eddy Probe
• Measure Relative
Distance Between
Two (2) Surfaces
• Accurate Low
Frequency
R
esponse
• Limited High Frequency Sensitivity
• R
equire External PowerSource

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Slide 22
15-07-08 ©SKF
Velocity Sensors
• Often Measure Bearing
Housings orMachinery Casing
Vibration
• Effective in Low to Mid
Frequency Range (10 Hz to
around 1,500 Hz)
• Self Generating Devices
• Are Electro-Mechanical Devices
W
ith Moving Parts That Can
StickorFail

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Slide 23
15-07-08 ©SKF
Accelerometers
• R
ugged Devices
• Operate in W
ide Frequency
R
ange (Near0 to above 400 kHz)
• Good High Frequency Response
• Some Models Suitable ForHigh
Temperature
• R
equire Additional Electronics

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Slide 24
15-07-08 ©SKF
SensorRelationships
10 100 1,000 10,000
Frequency (Hz)
10
1.0
0.1
1
0.01
100
Displacement (mils)
Acceleration
(g's)
Velocity (in/sec)
Common Machinery
Operating Range
Amplitude
(mils, in/sec, g’s)

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Slide 25
15-07-08 ©SKF
Same Data in Velocity and
Acceleration
Velocity
Spectrum
Acceleration
Spectrum

15-07-08 ©SKF Slide 26
4
Vibration Analysis
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Slide 27
15-07-08 ©SKF
Detection vs. Analysis
Detection
Alarmlimits are established foreach measurement. W
hen the
measurement’s value exceeds its programmed alarmlimits, the
predictive maintenance software ordata collectornotifies the
analyst of a problem.
Analysis
Once detected, analyzing exceptional measurements provides
insight to the problemitself, and to its root cause.

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Slide 28
15-07-08 ©SKF
Types of Alarms
 Overall Vibration Limits
 Spectral Enveloping
 Spectral Bands
 Phase Alarms

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Slide 29
15-07-08 ©SKF
ISO Standard
Vibration Standard
ISO 2372-1974

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Slide 30
15-07-08 ©SKF
ISO Vibration Severity Chart

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Slide 31
15-07-08 ©SKF
Overall Vib. Alarm
Assessing
Overall
Vibration
Severity

15-07-08 ©SKF Slide 32
5
Vibration Spectrum
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Slide 33
15-07-08 ©SKF
W
hat is Vibration Analysis ?
Vibration Analysis is a measure of the energy being
emitted froma surface due to forced and natural
oscillatory movement. The energy is captured as
vibrations and displayed in two common form:
1. Time vs Magnitude - known as time wafe form
2. Magnitude vs frequency - known as FFT

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Slide 34
15-07-08 ©SKF
Typical Vibration Analysis Display
Formats
Overall Vibration (Trending)
FFT Spectrum(Trending/
Analysis)
Time W
aveform(Trending/
Analysis)
OtherProcessing Methods
– Acceleration Enveloping
– S
E
E

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Slide 35
15-07-08 ©SKF
FFT SpectrumAnalysis
FFT Spectrum
shows component vibration
signals at theirrespective
frequencies
low
freq.
high freq.
frequency
amplitude
frequency

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Slide 36
15-07-08 ©SKF
Spectral Pattern Recognition
(velocity spectrum)
1X
2X 3X
4X
frequency
amplitude
< 1X
low frequency rotational events and harmonics
(i.e. imbalance, misalignment, looseness, etc.)
high frequency events
(i.e. bearing or gear-mesh)
10X

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Slide 37
15-07-08 ©SKF
Spectral Example
1
2
3
baseline spectrum (norm)
higher than normal
1X vibration signal
1X
2X
3X
bearing
freq..
gearmesh
freq.
higher than normal
1X and bearing
vibration signals
Known good measurement collected
when
machine was known to be in good running
order.
1X running speed peak is significantly
higher than normal. Indicates a vibration
signal occurring once per shaft revolution.
Typically caused by misalignment or
imbalance.
Higher than normal 1X running speed
peak and bearing fault frequency peaks
indicate that 1X rotational problem has
caused bearing damage.

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Slide 38
15-07-08 ©SKF
Sources of Vibration
Specific patterns in the spectral signatures are
recognized as being related to specific
machine problems.
• Misalignment 1x or 2x shaft speed
• Imbalance 1x
• Bent shaft 1x or 2x Axial
• Looseness 2x to 10x
• Gearmesh # of teeth x RPM
• Bearing Defects bearing defect frequencies

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Slide 39
15-07-08 ©SKF
Misalignment
Angular
Misalignment
Parallel
Misalignment

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Slide 40
15-07-08 ©SKF
Velocity Measurement Showing
Misalignment

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Slide 41
15-07-08 ©SKF
Imbalance - Diagnosis
static imbalance -
vibration across machine
“in phase”
couple imbalance -
vibration across machine
“180 degrees out of
phase”

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Slide 42
15-07-08 ©SKF
Velocity measurement Showing
Imbalance

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Slide 44
15-07-08 ©SKF
Bent Shaft - Diagnosis
1 - axial measurements across machine
typically 180 degrees out of phase, and ...
2 - radial measurements across machine
are typically in phase

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Slide 45
15-07-08 ©SKF
Velocity measurement Showing Bent
Shaft Problem

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Slide 47
15-07-08 ©SKF
Enveloping measurement showing
Mechanical Looseness Problem
Journal bearing on 600 MWSteamTurbine

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Slide 48
15-07-08 ©SKF
Gear-mesh Frequencies
GMF = # of teeth x RPM

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Slide 49
15-07-08 ©SKF
GearDefects
• The gear mesh frequency is equal to the gear shaft
rotating speed times the number of teeth on that gear.
• The amplitude will vary with the load.
• Two equal gearboxes can have very different
amplitudes under the same loads.
• ALW
AYS collect a time domain spectrum on each gear
shaft bearing.

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Slide 50
15-07-08 ©SKF
Acceleration Measurement Showing
Gear-mesh Frequencies

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Slide 51
15-07-08 ©SKF
Mining Gearbox Time Domain
208 RPM

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Slide 52
15-07-08 ©SKF
W
hy Do Bearings Fail?
inadequate lubrication
- too much
- too little
- contaminated
excessive load caused by:
- misalignment
- imbalance
- bent shaft
- etc.....
improperhandling or
installation
age
flaw on outer race

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Slide 53
15-07-08 ©SKF
Enveloping
Band Pass Filter is specified
according to defect harmonic
frequencies of interest
low frequency events filtered out, high
frequency defect harmonics emphasized
due to low signal to noise ratio, these high
frequency harmonics are then summed and
folded back to the defect’s fundamental frequency
resulting enveloped signal,
measured in gE
defect fundamental
frequency
fundamental
frequency
harmonics

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s
ia
Jaka Rusdianto
Slide 54
15-07-08 ©SKF
Bearing Defect Frequencies
BPFO
Ball Pass Frequency Outer Race
BPFI
Ball Pass Frequency Inner Race
BSF
Ball Spin Frequency
FTF
Cage Frequency or
Fundamental Train Frequency

B
a
s
ic
V
ib
r
a
t
io
nA
n
a
l
y
s
is
– I
n
d
o
n
e
s
ia
Jaka Rusdianto
Slide 55
15-07-08 ©SKF
Acceleration Enveloping on bearing
with Outerrace defect

B
a
s
ic
V
ib
r
a
t
io
nA
n
a
l
y
s
is
– I
n
d
o
n
e
s
ia
Jaka Rusdianto
Slide 58
15-07-08 ©SKF
Enveloping Severity Chart
ISO 10816

Vibration Analysis by SKF Bearings.pdf

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