Download - VIBRASI LEVEL 2
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 1
GearBlades
Rolling ElementBearings
ShaftRotatingSpeed
2x
3x
JournalBearingsinstability
1 KHz 3KHz 25KHz
FFT - How to select Freq. Ranges, lines, Averages
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 2
Frequency Range
30dB
2Hz
20
10
0
-10
10KHz
Rel
ativ
e Se
nsiti
vity
Consider…Sensor…Instrument…Cables…Sensor Coupling
Useful Frequency Range10% limit -0.3f0 3dB limit -0.5f0
-20
-30
-40
Frequency [xf0]
Frequency Response of Sensor
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 3
Sensitivity vs Frequency Range
Sens
itivi
ty
Frequency
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 4
Vibration Pickups
GearBlades
Rolling ElementBearings
ShaftRotatingSpeed
2x3x
JournalBearingsinstability
1 KHz 3KHz 25KHzNon Contact Displacement
Velocity Probe
Accelerometer
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 5
Threaded & bonded stud
VIB 8.660
VIB 8.680 SET
Threaded & bonded transducer
VIB 6.10X
VIB 8.685 SET
Hand held probe
VIB 8.606
VIB 6.140
Magnetic holdercurved surfaces
VIB 6.140
VIB 8.736
2 20k 36k Hz
v
1510 10k 36k
Hz
v
10 1k 2k 36k Hz
v
22 15k Hz
v
VIB 6.12X
Coupling vs Frequency Range
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 6
Machine Signal Types
Stationary Signals
Non - Stationary Signals
- Vibration from rotating machines
- Vibration from reciprocating machines (short term)
- Vibration from run-ups and coast-down
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 7
Informasi penting tentang mesin
Amplitudovibrasi
frekuensi
Apa saja yang mungkin menyebabkan vibrasi ?
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 8
Analisa Amplitudo, Frekuensi dan Fase - 1
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Kondisi seringditemui
Single reference mark
1 x rpmSebanding dgnketidak balance, dominan pd radial (2x aksial)
1. Unbalance A
f1x
Pengukuran getaran :
Ha = 4
Aa = 3
Va = 4
Hb = 5
Vb = 3 Vc = 4
Ae = 7
Hc = 3Hd = 2 Vd = 4
Ad = 5
Ab = 4 Ac = 5
He = 15
Ve = 13 Vf = 13
Af = 8
Hf = 15
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 9
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 10
Analisa Amplitudo, Frekuensi dan Fase - 2
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pengukuran getaran :
Ha = 5
Aa = 7
Va = 4
Hb = 10
Vb = 10 Vc = 10
Ae = 4
Hc = 10Hd = 5 Vd = 4
Ad = 7
Ab = 15 Ac = 15
He = 4
Ve = 3 Vf = 4
Af = 5
Hf = 3
Ditandai timbulnya vibrasiaksial. Gunakan alat laser-alignment. Apabila mesinbaru dipasang terjadivibrasi, maka kemungkinanbesar karena misalignment.
Singledoubletriple
Sering 1 x & 2 x rpm. Kadang 3 x rpm
Dominan pd aksial, 50% atau lebih dariarah radial
2. Misalignment kopling atauporos bengkok
A
f1x 2x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 11
Analisa Amplitudo, Frekuensi dan Fase - 3
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Vibrasi akan timbulapabila bearing sdhparah. Gunakanvibrotip / shockpulse u deteksi awal
Tdk tentu,Berubah-rubah
Sangat tinggi, beberapa kaliRpm, 1x, 2x, 3x,4x … 10x…..
Tidak stabil, ukur percepatan, gunakanacceleration probe
3. Anti friction bearing buruk
A
f1x 2x 3x 4x
Pengukuran getaran :
Ha = 3
Aa = 4
Va = 2
Hb = 3
Vb = 4 Vc = 5-10
Ae = 4
Hc = 5-10Hd = 4 Vd = 3
Ad = 5
Ab = 3 Ac = 10-15
He = 4
Ve = 5 Vf = 3
Af = 2
Hf = 4
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 12
Analisa Amplitudo, Frekuensi dan Fase - 3
KETERANGANFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Excessive Clearance normally accompanied by FTP modulating other frequencies; can also sifnificantly affect balance sensitivity
Excessive Internal clearances
Sangat tinggi, beberapa kaliRpm, 1x, 2x, 3x,4x,5 x,6x
Tidak stabil, ukur percepatan, gunakanacceleration probe
3. Anti friction bearing buruk
A
f1x 2x 3x 4x
KETERANGANFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Frequency 3X or greater is the predominant multiple
Bearing turning on shaft
Sangat tinggi, beberapa kaliRpm, 3xor greater
Tidak stabil, ukur percepatan, gunakanacceleration probe
3. Anti friction bearing buruk
A
f1x 2x 3x 4x
KETERANGANFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Frequency 3X or greater is the predominant multiple
Bearing turning on shaft
Sangat tinggi, beberapa kaliRpm, 3xor greater
Tidak stabil, ukur percepatan, gunakanacceleration probe
3. Anti friction bearing buruk
A
f1x 2x 3x 4x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 13
Analisa Amplitudo, Frekuensi dan Fase - 7
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Seringbersamaan dgnunbalance / misalignment
2 referensiagak kacau
2 x rpmTinggi padaaksial
7. Mechanical looseness (Housing bearing aus)
A
f2x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 14
• Frequency Defect Remarks• 1-6X Excessive internal
Clearance
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 15
Why shock pulses for rolling bearing noise ?
Machine vibration Shock pulse range rolling bearingMaterial crackplastical / elasticaldeformation
1 000 10 000 100 00036 000 flog / Hz
velocity acceleration shock pulses ultra sound emission
Natural frequencies rolling bearing pieces
l = n ⋅ mf ≈ x ⋅ 1 / 1 mfnat ≈ x ⋅ 30 Hz
Example
d = n ⋅ 1 mmf ≈ x ⋅ 1/1 000 mfnat ≈ x ⋅ 30 000 Hz
a = n ⋅ μmf ≈ x ⋅ 1 / 1 00 000 mfnat ≈ x ⋅ 300 000 Hz
d a
fnat,O fnat, Ι fnat,B
l
fnat =x
cm
( ∼ , , )1m
1l
1d
1a m = Mass
c = stiffness
1
2
1 2
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 16
Pengukuran vibrasi dan jarak frekuensi
Component & Machine Vibration Frictional Vibration (Sliding, Rolling, Shock, Rubbing Vibrations)
Size of machine component Speed /Rolling speed
Acceleration Velocity
ShockPulses
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 17
Analisa Amplitudo, Frekuensi dan Fase - 4
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
pd rodagigi vibrasi segarisdengan pusat kontak. pd motor/gen vibrasi hilangbila mesin dimatikan. pd pompa/blower kemungkinan unbalance
Single1 x rpm, seolah-olah sepertiunbalance
Tidak besar, aksiallebih tinggi
4. Sleeve, metal, Jurnal bearing (friction bearing) / eksentrik
A
f1x
Pengukuran getaran :
Ha = 3
Aa = 7
Va = 4
Hb = 8
Vb = 7 Vc = 3
Ae = 4
Hc = 5Hd = 3 Vd = 5
Ad = 4
Ab = 15 Ac = 4
He = 4
Ve = 4 Vf = 4
Af = 5
Hf = 3
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 18
Alignment pada sleeve bearing
Posisi pada saatpekerjaan alignment
Posisi seharusnyapada saat setelahalignment
Sleeve bearing
Ball bearing
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 19
Analisa Amplitudo, Frekuensi dan Fase - 5
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pengukuran getaran :
Ha = 3
Aa = 3
Va = 4
Hb = 2
Vb = 3 Vc = 7
Ae = 8
Hc = 7Hd = 7 Vd = 7
Ad = 9
Ab = 4 Ac = 8
He = 6
Ve = 7 Vf = 3
Af = 5
Hf = 4
Tdk tentuSangat tinggiJumlah gigi xrpm
Rendah, ukurkecepatan & percepatan, gunakanacceleration
5. Rodagigiburuk ataubersuara
A
f1x 2x 3x 4x
tooth
Awal rusakbersuara, semakinlama keras.Vibrasi biasanyadalam toleransi.
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 20
Analisa Amplitudo, Frekuensi dan Fase - 6
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pengukuran getaran :
Ha = 3
Aa = 3
Va = 4
Hb = 2
Vb = 3 Vc = 7
Ae = 8
Hc = 7Hd = 7 Vd = 7
Ad = 9
Ab = 4 Ac = 8
He = 6
Ve = 7 Vf = 3
Af = 5
Hf = 4
tooth
Sering terjadipada saatpemasangan
Tdk tentuSangat tinggiJumlah gigi xrpm
Rendah, ukurkecepatan &percepatan, gunakan accel.
6. Gear mesh buruk ataubersuara(pada saatstart / stop)
A
f1x 2x 3x 4x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 21
Analisa Amplitudo, Frekuensi dan Fase - 7
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Seringbersamaan dgnunbalance / misalignment
2 referensiagak kacau
2 x rpmTinggi padaaksial
7. Mechanical looseness (Housing bearing aus)
A
f2x
Pengukuran getaran :
Ha = 3
Aa = 3
Va = 4
Hb = 12
Vb = 12 Vc = 5
Ae = 4
Hc = 5Hd = 4 Vd = 5
Ad = 3
Ab = 15 Ac = 5
He = 4
Ve = 3 Vf = 3
Af = 4
Hf = 2
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 22
Analisa Amplitudo, Frekuensi dan Fase - 8
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Kurang dari1 x rpm
Tinggi padavertikal
8. Mechanical Looseness (Pondasikendor – dudukanlemah/karatan –baut kendor)
A
f<1x
Pengukuran getaran :
Ha = 2
Aa = 3
Va = 9
Hb = 4
Vb = 10 Vc = 5
Ae = 4
Hc = 2Hd = 4 Vd = 3
Ad = 2
Ab = 4 Ac = 2
He = 3
Ve = 3 Vf = 2
Af = 3
Hf = 4
Tdk tentu Kencangkan bautUntuk memastikan
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 23
Analisa Amplitudo, Frekuensi dan Fase - 9
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Seringbersamaan dgnunbalance / misalignment
2 referensiagak kacau
2 x rpmTinggi padavertikal, horizontal & aksial
9. Mechanical looseness (Pondasimelengkung)
A
f2x
Pengukuran getaran :
Ha = 13
Aa = 7
Va = 9
Hb = 14
Vb = 12 Vc = 5
Ae = 4
Hc = 5Hd = 4 Vd = 5
Ad = 3
Ab = 6 Ac = 5
He = 4
Ve = 3 Vf = 3
Af = 4
Hf = 2
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 24
Analisa Amplitudo, Frekuensi dan Fase - 10
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
1 atau 2 tergantungfrekuensi, tdk tetap
1,2,3 atau 4 x rpm belt
Tdktentu/berpulsa
10. Drive belt buruk
A
f1x 2x 3x 4x
Pengukuran getaran :
Ha = 2
Aa = 2
Va = 3
Hb = 4
Vb = 2 Vc = 10
Ae = 8
Hc = 10Hd = 8 Vd = 10
Ad = 10
Ab = 3 Ac = 10
He = 7
Ve = 8 Vf = 4
Af = 3
Hf = 2
Belt
Biasanya terjadikarena belt tdk beradapada tempatnya secarasempurna.
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 25
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 26
Analisa Amplitudo, Frekuensi dan Fase - 11
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pengukuran getaran :
Ha = 8
Aa = 6
Va = 7
Hb = 8
Vb = 6 Vc = 4
Ae = 3
Hc = 5Hd = 3 Vd = 3
Ad = 5
Ab = 7 Ac = 5
He = 3
Ve = 3 Vf = 2
Af = 3
Hf = 1
Vibrasi & suarahilang bilamesin dimatikan
Single/rotate double mark
2 x rpm lebihtinggi daripd1 x rpm.
Tidak tinggi, adasuaraberdengung, lebih terasa biladimatikan
11. Elektrikal A
f1x 2x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 27
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 28
Analisa Amplitudo, Frekuensi dan Fase - 12
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pengukuran getaran :
Ha = 2
Aa = 1
Va = 1
Hb = 2
Vb = 2 Vc = 4
Ae = 7
Hc = 3Hd = 4 Vd = 4
Ad = 3
Ab = 3 Ac = 5
He = 13
Ve = 14 Vf = 13
Af = 7
Hf = 14
Lebih terasa bilabeban tidakstabil.
1 x rpm ataujumlah suduatau fan atauimpeler x rpm
Tinggi padavertikal atauhorizontal
12. Gayaaerodinamik / hidrolik
A
f1x Jml x
Tdk tentu
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 29
Analisa Amplitudo, Frekuensi dan Fase - 13
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Pada mesinreciprocating bisa gantidesain/isolasi
1 x,2 x rpm atau lebih
13. Gayareciprocating
A
f1x 2x
Pengukuran getaran :
Ha = 8
Aa = 6
Va = 7
Hb = 7
Vb = 8 Vc = 3
Ae = 3
Hc = 2Hd = 4 Vd = 3
Ad = 4
Ab = 7 Ac = 4
He = 4
Ve = 2 Vf = 2
Af = 3
Hf = 2
Dominan aksial Single,double,triple
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 30
Ringkasan Analisa Amplitudo, Frekuensi dan Fase
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Kondisi seringditemui
Single reference mark
1 x rpmSebanding dgnketidak balance, dominan pd radial (2x aksial)
1. Unbalance A
f1x
Ditandai timbulnya vibrasiaksial. Gunakan alat laser-alignment. Apabila mesinbaru dipasang terjadivibrasi, maka kemungkinanbesar karena misalignment.
Singledoubletriple
Sering 1 x & 2 x rpm. Kadang 3 x rpm
Dominan pd aksial, 50% atau lebih dariarah radial
2. Misalignment kopling atauporos bengkok
A
f1x 2x
Vibrasi akan timbulapabila bearing sdhparah. Gunakanenveloping & shockpulse
Tdk tentu,Berubah-rubah
Sangat tinggi, beberapa kaliRpm, 1x, 2x, 3x,4x … 10x… x
Tidak stabil, ukur acceleration untuk freq. tinggi
3. Anti friction bearing buruk
A
f1x 2x 3x 4x
pd rodagigi vibrasi segarisdengan pusat kontak. pd motor/gen vibrasi hilangbila mesin dimatikan. pd pompa/blower kemungkinan unbalance
Single1 x rpm, seolah-olah sepertiunbalance
Tidak besar, aksiallebih tinggi
4. Sleeve, metal, Jurnal bearing (friction bearing)
A
f1x
Tdk tentuSangat tinggiJumlah gigi xrpm
Rendah, ukurkecepatan & percepatan, gunakan accel.
5. Rodagigiburuk ataubersuara
A
f1x 2x 3x 4x
Awal rusak bersuara, semakin lama keras.Vibrasi biasanyadalam toleransi.
tooth
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 31
Analisa Amplitudo, Frekuensi dan Fase - 2
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Sering terjadipada saatpemasangan
Tdktentu
Sangat tinggiJumlah gigi xrpm
Rendah, ukurkecepatan &percepatan, gunakan accel.
6. Gear mesh buruk ataubersuara padasaat start/stop
A
1xf
2x 3x 4x
Seringbersamaan dgnunbalance / misalignment
2 referensiagak kacau
2 x rpmTinggi padaaksial
7. Mechanical looseness (Housing bearing aus)
A
f2x
Kurang dari1 x rpm
Tinggi padavertikal
8. Mechanical Looseness (Pondasikendor – dudukanlemah/karatan –baut kendor)
A
f<1x
Tdk tentu Kencangkan bautUntuk memastikan
Seringbersamaan dgnunbalance / misalignment
2 referensiagak kacau
2 x rpmTinggi padavertikal, horizontal & aksial
9. Mechanical looseness (Pondasimelengkung)
A
f2x
1 atau 2 tergantungfrekuensi, tdk tetap
1,2,3 atau 4 x rpm belt
Tdktentu/berpulsa
10. Drive belt buruk
A
f1x 2x 3x 4x
Biasanya terjadikarena belt tdk beradapada tempatnya secarasempurna.
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 32
Analisa Amplitudo, Frekuensi dan Fase - 3
KETERANGANFASEFREKUENSIAMPLITUDOPENYEBAB GAMBAR SPECTRUM
Vibrasi & suarahilang bilamesin dimatikan
Single/rotate double mark
2 x rpm lebihtinggi daripd1 x rpm.
Tidak tinggi, adasuara dengung, lbh terasa biladimatikan
11. Elektrikal A
f1x
Lebih terasa bilabeban tidakstabil.
1 x rpm / jmlsudu / fan atau impelerx rpm
Tinggi padavertikal atauhorizontal
12. Gayaaerodinamik / hidrolik
A
f1x Jml x
Pada mesinreciprocating bisa gantidesain/isolasi
1 x,2 x rpm atau lebih
13. Gayareciprocating
A
f1x 2x
Tdk tentu
Single,double,triple
Dominan aksial
2x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 33
Latihan - 1
PICKUP LOCATION Peak (mm/s)
FREQ(cpm)
Peak(mm/s)
FREQ(cpm)
Peak(mm/s)
FREQ(cpm)
Peak(mm/s)
FREQ(cpm)
0.080.07
-
-0.4
0.45
0.250.300.42
Variable 37500Variable 37500
-
-14001400
140014001400
600060006000
600060006000
75007500
-
75007500
-
0.050.050.01
0.050.050.01
0.050.4-
0.40.05
-
300030003000
300030003000
30003000
-
30003000
-
0.30.5
0.09
0.40.7
0.15
0.20.15
-
0.20.09
-
150015001500
150015001500
150015001500
150015001500
1.72.41.2
2.1
3.21.9
1.11.31.2
1.31.11.5
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
A
B
C
D
Single phasemotor
Coupling
5 bladeimpeller
Sleevebearing
Rollerbearing
A B C D
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 34
PERTANYAAN : LATIHAN-1
(a) Kemungkinan penyebab apa yang mengakibatkan terjadinyavibrasi 1500 cpm pada bearing A dan B ?
(b) Bila kemungkinan penyebabnya lebih dari satu, bagaimana caraAnda untuk menemukan penyebab yang sesungguhnya ?
(c) Apa penyebab terjadinya vibrasi 3000 cpm pd bearing A,B,C & D ?
(d) Apa penyebab terjadinya vibrasi 6000 cpm pd bearing A dan B ?
(e) Apa penyebab terjadinya vibrasi 37500 cpm pd bearing B ?
(f) Apa penyebab terjadinya vibrasi 7500 cpm pd bearing C dan D ?
(g) Apa penyebab terjadinya vibrasi 1400 cpm pd bearing C dan D ?
(h) Bagaimana Anda menentukan apakah penyebab vibrasi tersebutharus ditanggulangi ?
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 35
Latihan - 2
PICKUP LOCATION DISP FREQ DISP FREQ DISP FREQ DISP FREQ
1.21.3
4000040000
450045004500
450045004500
13001300
130013001300
1.31.10.9
1.21.21.0
2.02.1
2.12.22.0
300030003000
300030003000
1800018000
-
1800018000
-
1.21.21.3
1.21.40.9
0.91.1-
1.31.2-
150015001500
150015001500
150015001500
150015001500
2.72.81.3
1.81.91.2
1.21.11.1
1.21.31.1
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
VertikalHorizontal
Aksial
A
B
C
D
Water turbine12 blades
CouplingGenerator
Rollerbearing
Sleevebearing
A B C D
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 36
PERTANYAAN : LATIHAN-2
aa) Kemungkinan penyebab apa yang mengakibatkan terjadinya vibrasi 1500 cpm padabearing A dan B ?
b) Bila kemungkinan penyebabnya lebih dari satu, bagaimana cara Anda untuk menemukanpenyebab yang sesungguhnya ?
(c) Apa penyebab terjadinya vibrasi 3000 cpm pada bearing A dan B ?(d) Apa penyebab terjadinya vibrasi 40000 cpm pada bearing A ?(e) Apa penyebab terjadinya vibrasi 4500 cpm pada bearing A dan B ?(f) Apa penyebab terjadinya vibrasi 18000 cpm pada bearing C dan D ?(g) Apa penyebab terjadinya vibrasi 1300 cpm pada bearing C dan D ?h) Bagaimana Anda menentukan apakah penyebab vibrasi tersebut harus ditanggulangi ?
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 37
Latihan - 3
5 blade impeller
Sleevebearing
C DSingle phase motor
Rollerbearing
A B1500 rpm
3000 rpm
PICKUP LOCATION AMPL FREQ AMPL FREQ AMPL FREQ AMPL FREQ
1.21.3
4000040000
450045004500450045004500130013001300130013001300
1.31.10.91.21.21.01.92.02.12.12.22.0
300030003000300030003000
360003600036000360003600036000
1.21.21.31.21.40.90.91.11.11.31.21.1
150015001500150015001500300030003000300030003000
2.82.92.44.04.14.94.54.44.83.83.93.3
VertikalHorizontal
AksialVertikal
HorizontalAksial
VertikalHorizontal
AksialVertikal
HorizontalAksial
A
B
C
D
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 38
Latihan - 4
PICKUP LOCATION AMPL FREQ AMPL FREQ AMPL FREQ AMPL FREQ
1.21.3
1.41.21.31.21.11.1
4000040000
240002400024000240002400024000
450045004500450045004500130013001300130013001300
1.31.10.91.21.21.01.92.02.12.12.22.0
300030003000300030003000
360003600036000360003600036000
1.21.21.31.21.40.90.91.11.11.31.21.1
150015001500150015001500300030003000300030003000
2.82.92.44.04.14.94.54.44.83.83.93.3
VertikalHorizontal
AksialVertikal
HorizontalAksial
VertikalHorizontal
AksialVertikal
HorizontalAksial
A
B
C
D
compressor
Sleevebearing
C DSingle phase motor
Rollerbearing
A B1500 rpm
3000 rpm
gearbox
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 39
Machine Signal Types
Pulsed• RE Bearing Wear• Rubs• Blade Damage, fouling• Surge, Cavitation, • Local Tooth Defects
Random•Lubrication Problems• Rolling Element (RE)Bearing Mounting defect• Flow Exited
Semi Static• Shaft Position
Modulated• Torsional Load• Tooth Fatigue• Eccentricity
1X 2X 200Hz
1X 5 kHz
1X 10 kHz
1X 10 kHz
Harmonic•Imbalance•Misalignment
Time Frequency
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 40
Penyebab vibrasi dan frekuensi karakteristiknyaPossible Dominant Direction Comments
cause FrequencyUnbalance 1x rotation frequency Radial for dyna- Amplitude proportional to unbalance and RPM;
mic imbalance, caused by displacement of rotation axis from masspossibly axial center of gravity
Misalignment; 1x rotation frequency Radial and Severe axial vibration and 2nd harmonic; bestbent shaft often 2x and higher axial realigned with ROTALIGN©, OPTALIGN© V or SYSTEM
multiples 2 TURBALIGN©
Bearing High frequency vibration, Radial and May be diagnosed from vibration only throughdamage Shock pulse vibration axial use of diagnostic functions, shock pulse analysis
or envelope curve analysis.Sleeve Subharmonic, exactly Radial Usually dependent upon RPM and operatingbearing play 1/2 or 1/3 of rotation temperature.
frequencyOil film whirl 40% - 50% of rotation Radial Occurs with high-speed machines; phaseor whip (sleeve frequency fluctuates.bearings)Hysteresis Critical shaft rotation Radial Vibrations are excited as machine climbs throughwhirl frequency critical RPM and remain at higher speeds. Remedy :
Rotor must be reworked (mounting improved).Gear tooth Tooth mesh frequency Radial and Sidebands occur from modulation of tooth meshdamage and multiples thereof axial vibration at rotation frequency; may be isolated using
with sidebands located envelope analysis.at multiples of rotationfrequency
Belt drive Rotation frequency and Radial Additionally recommended : combined RPM and beltdamage multiples thereof speed measurements to check for belt slippage.Turbulence; Blade/vane passing Radial and Additionaly recommended for pumps : shock pulsecavitation frequency axial measurement at the pump housing.Electrically Rotation frequency, Radial and Sidebands may also occur located at multiplesinduced 2x line frequency axial of the rotation frequency; vibration ceases when powervibration is cut off.Frequency Multiples of motor line Radial Disappears in direct line operation; proportionalalternator frequency to motor line frequency.signal
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 41
Contoh lapangan : Sifter
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 42
Spectra frekuensi dari Sifter
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Contoh no. 2 : Turbocompressor
Tidak lama sebelumperbaikan total
Tidak lama setelahperbaikan total
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 44
Contoh no. 3 : Foundry Fan
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 45
Contoh no. 4 : Tunnel Furnace Fan
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 46
Contoh : Pompa centrifugal
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 47
• Evaluation criteria:ISO 10816-3
Symptom : High Amplitude at fn
Unbalance
Machine spectrum:
v [mm/s]
fn f [Hz]
• Fundamental Freq. Fn = RPM [Rev/min]60
fn f n
Misalignment
Machine spectrum:v
[mm/s]
fn 2xfn f [Hz]
Symptom : Increased amplitude visible at fn and/ or 2x
• First and Second order of rotor frequency
Radial : parallel misalignmentaxial : angular misalignment
•
Machine Vibration Example 1
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 48
Gear mesh faults
2xfz 3xfz 4xfz
Symptom : Harmonics of fzvisible
fn1
fn2
z1
z2
fz f (Hz)
Machine Spectrum:a
mm/s²
• Gear mesh frequency fz = fn1. Z1= fn2. Z2
• fn1 : rotational frequency driven shaft
•
Z, Z2 : number of gear teeth
Cracked / Broken Tooth
fn1fn2
z1 z2
fz 2xfz 3xfz f (Hz)
Machine Spectrum:amm/s²
Symptom : Side bands with fn• Side band distance fn is the fundamental frequency
of the defective gear (broken tooth)• many side bands around fz gear mesh with slowly
decreased amplitudes
Machine Vibration Example 2
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 49
Machine Vibration Example 3
Bad foundation
fn
nf f (Hz)
Machine spectrum:v mm/s
2xfn 3xfn 4xfn
Symptom : Harmonics of fn are visible
• Root Cause: Resonance or Instability
fundamental freq. fn =•RPM[Rev/min]
60
Turbulencess=9
fn
x=3(e.g. fixture for bearing)
f (Hz)
Machine spectrum:
fn fBPF x ∗ fBPF
v mm/s
Symptom : Blade pass frequency fBPF
• Blade pass frequency fBPF = fn . s•• s: number of blades• x: number of disturbance locations
Higher orders x*fBPF = fn . s . x
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 50
Machine Vibration Example 4
Resonance
a) Machine spectrumVmm/s
fn f (Hz)
c) Waterfall diagram velocityspectra in coast down
Resonance step-up
vmm/s
n (Rev/min)Natural frequency f (Hz)
nf 2xfn 3xfn
fn
2xfn 3xfn 4xfn 5xfn
Symptom : Harmonics of fn visiblepreferably uneven multiples
fundamental freq. fn =•RPM[Rev/min]
60
b) Bode diagram in coast down
ϕ(°)
Phase shift of 180°
nRes. n in Rev/min
vmm/s
nRes.
Resonance step-up
n in Rev/min
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 51
Productive Maintenance Technology
BEARING CONDITIONMEASUREMENT
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 52
Types of Bearings
Journal Bearings• Stationary Signals• Relative Low Frequency• Displacement transducer
Journal Bearings• Stationary Signals• Relative Low Frequency• Displacement transducer
Rolling Element Bearings• Modulated Random Noise• Pulsating signals• High Frequency• Accelerometers
Rolling Element Bearings• Modulated Random Noise• Pulsating signals• High Frequency• Accelerometers
Use Proximity probes
Use Accelerometers
Monitoring Techniques
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 53
VIR > VRE > VOR > VRC
fIR > fRE > fOR > fRC
bearing clearance
contact no air gap
breaking impulseroller enters load zone
load zone = measuring zone
v(fn)
V c
V b
Fcentrifugal, rolling element
Fdyn., rotor
Fstat, rotor
acceleration impulseroller leaves load zone
vibration
shaft
housing
Example:
bearing type 62222C3 = 0.05 mm
gap
C3
Hertzsurface pressure
Forces and Motions in Rolling Bearings
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 54
A Typical Bearing Life Cycle
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Types of Rolling Bearing Damages (1)
Damages types/ Causes
- lifetime expired- overloading- assembly /
- greasing deficiencymanufacturing error
shock pulses
wear
wear
1 Wear
2 Damage torolling track
- lifetime expired- bearing overloaded- bearing under-loaded- greasing deficiency
damage
envelope
shock pulses
3 Contaminated lubricant
- Damaged rolling track- damaged sealing- contaminated
lubricant
high variation in shock pulse levels
and defect frequencies
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 56
Types of Rolling Bearing Damages (2)
Damages types/ Causes
4 Greasing deficiency
- greasing deficiencyUnder-loading-
temperature rises very late
5 Unround deformation of bearing race
- assembly error- manufacturing defect
in shaft or bearing housing
damagefrequenciesin envelope
shock pulsesair gap
dirt
6 Jammed loose bearing
- in bearing housing(sliding fit)
- mis-calculation of housing design
high vibrationincreasing bearing
temperature
fixed bearing loose bearing
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 57
Types of Rolling Bearing Damages (3)
Damages types/ Causes
7 ExcessiveGreasing
- maintenance error (quantity, interval)
- defective grease grease drain
Large temperature-Increase after greasing
8 Installed at anangle
- assembly errorWhistling
Bearing noise
clearance too small9 Rolling bearing
- assembly error at
-inner race diameter
- got hot by friction after greasing deficiency
bearing with taper sleeveshaft diameter to large to
Large temperatureincrease after greasing
deficiency
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 58
Types of Rolling Bearing Measurement Methods
k (t) Method Spike Energy ValueBCU Value Kurtosis FactorgSE - Factor
SEE Factor Acceleration Crest Factor
Shock pulse measurement
?
?
•••
NormalisingAlarm Levels Gradient of trend development is necessary for evaluation of rollingbearing condition
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 59
i
ideal measurement
dB
dB = normalised shock pulse value
dBi = initial value• Basic normalised shock pulse value• function of RPM and shaft diameter
n
dBi = (f(φ, rpm)
dBn = dBsv – dBi
-9
0
90dBsv
dBsv= absolute shock pulse value
dBia = (f(φ, rpm)
dBn = dBsv – dBia
dBia = dBi + dBa
Where dBa(dB) is the adjusting value
measurement location with signal damping
dBsv
0
90
-9
dBia
dBm
dBc
dBm
dBc
dBn
dBia = adjusted initial value• Actual measurement location
(not at load zone)• influencing factors like load condition
lubrication and bearing type
Normalising of Shock Values
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 60
Normalising of Shock Pulse Measurements
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 61
d
n - number of rolling elements in contact with damage
ba - extent of damage torolling bearing component
0 good
ac
at
1 very small- small material defects- several pitting- defect frequencies are visible
in envelope spectrum
2 small - slight material splintering- Max values of shock pulses begin to rise
when rolling element passes over defect
Extent of rolling bearing surface damage
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 62
3 medium - one roller drops into slight depression caused by damage to rolling track
- maximum values rise perceptibly
- one or more rollers drop into large depression by damage to rolling track
- maximum values rise dramaticallycarpet values rise continuously
4 large
- carpet values rise substantially- bearing approaching crash- componentsmay break- increasing machine vibrations- rotor drops into very large depression- several rollers drop into severe
5 very large
Extent of rolling bearing surface damage
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 63
Productive Maintenance Technology
ENVELOPE ANALYSIS
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 64
Envelope Analysis – Rolling Bearings Fault Detection
No rolling track defect:
Time signal:a
m/s2
t (s)
am/s2
t (s)
Rectification
Envelope
am/s2
t (s)
Enveloping
f (Hz)
am/s2
Envelope spectrum:
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 65
Rolling track defect:
Time signal:a
m/s2
t (s)
am/s2
t (s)
Rectification
am/s2
Envelope
t (s)
Enveloping Envelope spectrum:a
m/s2
fRPOF
2• 3• 4• f (Hz)
Defect frequency
fRPOF
fRPOF
fRPOF
(Hz)• fRPOF=
1TRPOF
Envelope Analysis – Rolling Bearings Fault Detection
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 66
Roller Bearing Race Track DefectsOuter Race Defect:
2fRPOF3fRPOF4fRPOF5fRPOF
Envelope Spectrum:a
m/s²
f (Hz)fRPOF
Rolling element pass outer race fRPOF and harmonics clearly visible• if only fRPOF appears, then it can also be an unround
deformation of the outer race track
• In the case of very big unbalance, side bands with interval
(in the load zone modulation with fn as the unbalance runsfn appear because of periodic load changes
periodically through the load zone)
Inner Race Defect:
f 2xfRPIFRPIF
Envelope Spectrum:a
m/s²
f (Hz)
Rolling element pass inner race frequency fRPIFand many side bands with interval fn
• Modulated with the fundamental frequency fn as the innerrace defect runs periodically through the load zone with fn
• Fundamental modulation frequency fn and harmonics are visible
Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 67
Roller Bearing Defects – Part 3 Rolling element defect:
Rolling element pass frequency fRPFwith harmonicsAnd side bands with interval fCRF• fRPFcan be also visible because of too small bearing clearance
or insufficient lubrication• Modulation with cage rotational speed fCRF , as the rolling
element runs periodically through the load zone with fCRF• Sub-harmonics of fRPF exist always with the harmonics, because the
pulse on outer race gives a higher level as pulses on the inner race • Fundamental modulation frequency fCRFand harmonics are visible
Cage Defect:
2 fCRF CRF3 f 4 fCRF
Cage rotational frequency fCRF and harmonics
• fCRFcage rotational frequency is cage defect frequency
• coming out of the load zone: the rolling element is accelerated and slides on the cage defect
• or coming into the load zone: the rolling element is braked and slideson the cage defect
visible
f0.5 RPF RPF•f 1.5•fRPF RPF2•fRPF RPF3•f
Envelope Spectrum:a
m/s²
f (Hz)2.5 f•
Envelope Spectrum:a
m/s²
f (Hz)CRFf