VIBRASI LEVEL 2

t o sele s elect ct Freq. Freq. Rang Ranges, es, lines, Averages FFT - How to

Shaft Rotating Speed Journal Bearings instability

Blades 2x

Roll olling ing Eleme lement nt Bearings

Gear 3x

1 K Hz

3KHz

25KHz

Copyright 2004 2004-- PT. PT. Putrana Putranata ta Adi Mandiri Mandiri – sole agent agent Prüftechnik Prüftechnik AG, Germany Germany – PART PART 2

1

Frequency Range ng e

y t i v i t i s n e S e v i t a l e R

30 dB 20

Usefu Usefull Frequ Freque ency nc y Rang Range e 10% limit -0.3f 0 3dB limit -0.5f 0

10 Frequency Response of Sensor

0 -10 -20 -30 -40

2Hz

10KHz Frequency [xf 0]

Consider…Sensor…Instrument…Cables…Sensor Coupling Copyright 2004 2004-- PT. PT. Putrana Putranata ta Adi Mandiri Mandiri – sole agent agent Prüftechnik Prüftechnik AG, Germany Germany – PART PART 2

2

Frequency Range ng e

y t i v i t i s n e S e v i t a l e R

30 dB 20

Usefu Usefull Frequ Freque ency nc y Rang Range e 10% limit -0.3f 0 3dB limit -0.5f 0

10 Frequency Response of Sensor

0 -10 -20 -30 -40

2Hz

10KHz Frequency [xf 0]

Consider…Sensor…Instrument…Cables…Sensor Coupling Copyright 2004 2004-- PT. PT. Putrana Putranata ta Adi Mandiri Mandiri – sole agent agent Prüftechnik Prüftechnik AG, Germany Germany – PART PART 2

2

Sensitivity nsiti vity vs Freque requency ncy Ra Range

y t i v i t i s n e S

Frequency Copyright 2004 2004-- PT. PT. Putrana Putranata ta Adi Mandiri Mandiri – sole agent agent Prüftechnik Prüftechnik AG, Germany Germany – PART PART 2

3

Vibration Pickups

Journal Bearings instability

Shaft Rotating Speed 2x

Rolling Element Bearings Blades Gear 3x

1 KHz

3KHz

25KHz

Non Contact Displacement Velocity Probe Acceler om eter

Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

4

Coupling vs Frequency Range

Threaded & bon ded stud

Threaded & bonded transducer VIB 6.10X

Hand held probe

Magnetic holder curved surfaces

VIB 6.12X

VIB 8.660 VIB 6.140

VIB 6.140 VIB 8.606

VIB 8.680 SET

VIB 8.685 SET

v

VIB 8.736

v

10 5 Hz

10k

36k

v

v

2 1 Hz

20k 36k

10 2

1k

2k

36k

Hz

2


15k Hz

5

Machine Signal Types

Stationary Signals

- Vibration from rotating machines

Non - Stationary Signals - Vibration from reciprocating machines (short term) - Vibration from run-ups and coast-down


6

Infor nf orma masi si pent pentin ing g tent tenta ang mesin mesin

Am A m p l i t udo ud o vibrasi

frekuensi

Ap A p a s aja aj a y ang an g m u n g k i n m eny en y ebab eb abk k an v i b r asi as i ? Copyright 2004 2004-- PT. PT. Putrana Putranata ta Adi Mandiri Mandiri – sole agent agent Prüftechnik Prüftechnik AG, Germany Germany – PART PART 2

7

An A n ali al i s a A m p l i t u d o , Frek Fr eku u ens en s i d an Fase Fas e - 1 PENYEBAB

AMPLITUDO

FREKUENSI

FASE

KETERANGAN

GAMBAR SPECTRUM

1. Unbalance

Seban Sebandin ding g dgn ketidak ketidak balance, balance, domi domina nan n pd radial (2x aksial)

1 x rpm

Single reference mark

Kondis Kondisii sering sering

A

ditemui f 1x

Ve = 13

Vf = 13

Pengukur ngukura an geta getara ran n: A e = 7

A f = 8

Va = 4 Vb = 3

Vc = 4 He = 15

A a = 3

A b = 4

Hf = 15

A c = 5 A d = 5

Ha = 4

Hb = 5 Hc = 3 Hd = 2

Vd = 4


8


9

Analisa Amplitudo, Frekuensi dan Fase - 2 PENYEBAB

AMPLITUDO

FREKUENSI

FASE

KETERANGAN

2. Misalignment kopling atau poros bengkok

Dominan pd aksial, 50% atau lebih dari arah radial

Sering 1 x & 2 x rpm. Kadang 3 x rpm

Single

Ditandai timbulnya vibrasi A aksial. Gunakan alat laseralignment. Apabila mesin baru dipasang terjadi vibrasi, maka kemungkinan besar karena misalignment.

double triple

Ve = 3

GAMBAR SPECTRUM

f 1x

2x

Vf = 4

Pengukuran getaran : A e = 4

A f = 5

Va = 4 Vb = 10

Vc = 10 He = 4

A a = 7

A b = 15

Hf = 3

A c = 15 A d = 7

Ha = 5

Hb = 10 Hc = 10 Hd = 5

Vd = 4


10


AMPLITUDO

3. Anti friction bearing buruk

FREKUENSI

Tidak stabil, ukur percepatan, gunakan acceleration probe

FASE

KETERANGAN

Sangat tinggi, beberapa kali

Tdk tentu,

Rpm, 1x, 2x, 3x,

rubah

Berubah-

GAMBAR SPECTRUM

Vibrasi akan timbul apabila bearing sdh parah. Gunakan vibrotip / shockpulse u deteksi awal

4x … 10x…..

Ve = 5

A

f 1x

2x

3x

4x

Vf = 3


A f = 2

Va = 2 Vb = 4

Vc = 5-10 He = 4

A a = 4

A b = 3

Hf = 4

A c = 10-15 A d = 5

Ha = 3

Hb = 3 Hc = 5-10 Hd = 4

Vd = 3


11



PENYEBAB


PENYEBAB


AMPLITUDO


AMPLITUDO

Tidak stabil, ukur percepatan, gunakan acceleration probe AMPLITUDO


FREKUENSI

Sangat tinggi, beberapa kali Rpm, 1x, 2x, 3x,

KETERANGAN

Excessive Internal clearances

4x,5 x,6x

FREKUENSI

Sangat tinggi, beberapa kali Rpm, 3x

A Excessive Clearance normally accompanied by FTP modulating other frequencies; can also sifnificantly affect balance sensitivity

KETERANGAN

Bearing turning on shaft

GAMBAR SPECTRUM

Frequency 3X or greater is the predominant multiple

Rpm, 3x or greater

4x

f

KETERANGAN

Bearing turning on shaft

3x

A

1x

FREKUENSI

2x

GAMBAR SPECTRUM

or greater

Sangat tinggi, beberapa kali

f 1x

Frequency 3X or greater is the predominant multiple

2x

3x

4x

GAMBAR SPECTRUM

A

f 1x

2x


3x

4x

12


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

7. Mechanical looseness (Housing bearing aus)

Tinggi pada aksial

2 x rpm

2 referensi Sering agak kacau bersamaan dgn unbalance / misalignment

GAMBAR SPECTRUM

A

f 2x


13

• Frequency

Defect

Remarks

• 1-6X Clearance

Excessive internal


14

Why shock pulses for rolli ng bearing no ise ? c

f nat =

(

m

x

1 m

∼

1 l

,

1 d

,

1 a

c = stiffness

) m = Mass

Material crack Shock pulse range rolling bearing

Machine vibration

plastical / elastical deformation

Natural frequencies rolling bearing pieces f nat,O

f nat,B

f nat, 2 1

Example

l

1

d

l = n

⋅

m

f

x

⋅

1/1m

x

⋅

30 Hz

≈

f nat

≈

d = n

⋅

1 mm

f

x

⋅

1/1 000 m

x

⋅

30 000 Hz

≈

f nat

1 000

2

≈

10 000

a

a

36 000

100 000

=n

⋅ μm

f

≈

x

f nat

≈

x 3 00 000 Hz

⋅

1 / 1 00 000 m

⋅

f log / Hz

velocity sound shock pulses Copyright 2004- PT. Putranata Adiacceleration Mandiri – sole agent Prüftechnik AG, Germany –ultra PART 2 emission 15

Pengukuran vibrasi dan jarak frekuensi Component & Machine Vibration

Frictional Vibration (Sliding, Rolling, Shock, Rubbing Vibrations)

Size of machine com ponent

Velocity

Accelerat ion

Speed / Rolling s peed

Shock Pulses


16


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

4. Sleeve, metal, Jurnal bearing (friction bearing) / eksentrik

Tidak besar, aksial

1 x rpm, seolaholah seperti unbalance

Single

pd rodagigi vibrasi segaris dengan pusat kontak. pd motor/gen vibrasi hilang bila mesin dimatikan. pd pompa/blower kemungkinan unbalance

lebih tinggi

Ve = 4

GAMBAR SPECTRUM

A

f 1x

Vf = 4


A f = 5

Va = 4 Vb = 7

Vc = 3 He = 4

A a = 7

A b = 15

Hf = 3

A c = 4 A d = 4

Ha = 3

Hb = 8 Hc = 5 Hd = 3

Vd = 5


17

Alignment pada sleeve bearing Posisi pada saat pekerjaan alignment

Sleeve beari ng

Posisi seharusnya pada saat setelah alignment

Ball bearin g


18


AMPLITUDO

5. Rodagigi buruk atau bersuara

Rendah, ukur kecepatan & percepatan, gunakan acceleration

FREKUENSI

FASE

KETERANGAN

Sangat tinggi

Tdk tentu

GAMBAR SPECTRUM

Awal rusak bersuara, semakin lama keras. Vibrasi biasanya dalam toleransi.

Jumlah gigi x rpm

Ve = 7

A

f 1x

2x

3x

4x

tooth

Vf = 3


A f = 5

Va = 4 Vb = 3

Vc = 7 He = 6

A a = 3

A b = 4

Hf = 4

A c = 8 A d = 9

Ha = 3

Hb = 2 Hc = 7 Hd = 7

Vd = 7


19


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

6. Gear mesh buruk atau bersuara (pada saat start / stop)

Rendah, ukur kecepatan &

Sangat tinggi

Tdk tentu

percepatan, gunakan accel.

rpm

GAMBAR SPECTRUM

Sering terjadi pada saat pemasangan

Jumlah gigi x

A

f 1x

2x

3x

4x

tooth

Ve = 7

Vf = 3


A f = 5

Va = 4 Vb = 3

Vc = 7 He = 6

A a = 3

A b = 4

Hf = 4

A c = 8 A d = 9

Ha = 3

Hb = 2 Hc = 7 Hd = 7

Vd = 7


20


AMPLITUDO

FREKUENSI

FASE

KETERANGAN


Tinggi pada aksial

2 x rpm


Ve = 3

GAMBAR SPECTRUM

A

f 2x

Vf = 3


A f = 4

Va = 4 Vb = 12

Vc = 5 He = 4

A a = 3

A b = 15

Hf = 2

A c = 5 A d = 3

Ha = 3

Hb = 12 Hc = 5 Hd = 4

Vd = 5


21


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

GAMBAR SPECTRUM

8. Mechanical Looseness (Pondasi kendor – dudukan lemah/karatan – baut kendor)

Tinggi pada vertikal

Kurang dari 1 x rpm

Tdk tentu

Kencangkan baut Untuk memastikan

A

f <1x

Ve = 3

Vf = 2


A f = 3

Va = 9 Vb = 10

Vc = 5 He = 3

A a = 3

A b = 4

Hf = 4

A c = 2 A d = 2

Ha = 2

Hb = 4 Hc = 2 Hd = 4

Vd = 3


22


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

9. Mechanical looseness (Pondasi melengkung)

Tinggi pada vertikal, horizontal & aksial

2 x rpm


Ve = 3

GAMBAR SPECTRUM

A

f 2x

Vf = 3


A f = 4

Va = 9 Vb = 12

Vc = 5 He = 4

A a = 7

A b = 6

Hf = 2

A c = 5 A d = 3

Ha = 13

Hb = 14 Hc = 5 Hd = 4

Vd = 5


23


AMPLITUDO

FREKUENSI

FASE

10. Drive belt buruk

Tdk tentu/berpulsa

1,2,3 atau 4 x rpm belt

1 atau 2 tergantung frekuensi, tdk tetap

Belt

KETERANGAN

GAMBAR SPECTRUM

Biasanya terjadi karena belt tdk berada pada tempatnya secara sempurna.

Ve = 8

A

f 1x

2x

3x

4x

Vf = 4


A f = 3

Va = 3 Vb = 2

Vc = 10 He = 7

A a = 2

A b = 3

Hf = 2

A c = 10 A d = 10

Ha = 2

Hb = 4 Hc = 10 Hd = 8

Vd = 10


24


25


AMPLITUDO

11. Elektrikal

Tidak tinggi, ada suara berdengung, lebih terasa bila dimatikan

FREKUENSI

FASE

KETERANGAN

2 x rpm lebih tinggi daripd

Single/

Vibrasi & suara hilang bila mesin dimatikan

rotate double mark

1 x rpm.

GAMBAR SPECTRUM

A

f 1x

Ve = 3

2x

Vf = 2


A f = 3

Va = 7 Vb = 6

Vc = 4 He = 3

A a = 6

A b = 7

Hf = 1

A c = 5 A d = 5

Ha = 8

Hb = 8 Hc = 5 Hd = 3

Vd = 3


26


27


AMPLITUDO

12. Gaya aerodinamik / hidrolik

Tinggi pada vertikal atau horizontal

FREKUENSI

FASE

1 x rpm atau jumlah sudu atau fan atau impeler x rpm

KETERANGAN

Tdk tentu

GAMBAR SPECTRUM

Lebih terasa bila beban tidak stabil.

A

f 1x

Ve = 14

Jml x

Vf = 13


A f = 7

Va = 1 Vb = 2

Vc = 4 He = 13

A a = 1

A b = 3

Hf = 14

A c = 5 A d = 3

Ha = 2

Hb = 2 Hc = 3 Hd = 4

Vd = 4


28


AMPLITUDO

FREKUENSI

FASE

13. Gaya reciprocating

Dominan aksial

1 x,2 x rpm

Single, double, triple

atau lebih

KETERANGAN

GAMBAR SPECTRUM

A

Pada mesin reciprocating bisa ganti desain/isolasi

Ve = 2

f 1x

2x

Vf = 2


A f = 3

Va = 7 Vb = 8

Vc = 3 He = 4

A a = 6

A b = 7

Hf = 2

A c = 4 A d = 4

Ha = 8

Hb = 7 Hc = 2 Hd = 4

Vd = 3


29

Ringkasan Analisa Amplitudo, Frekuensi dan Fase PENYEBAB

AMPLITUDO

FREKUENSI

FASE

KETERANGAN

1. Unbalance

Sebanding dgn ketidak balance, dominan pd radial (2x aksial)

1 x rpm

Single reference mark

Kondisi sering

Dominan pd aksial, 50% atau lebih dari arah radial

Sering 1 x & 2 x rpm. Kadang 3 x rpm

2. Misalignment kopling atau poros bengkok

Single double triple Tdk tentu,

4. Sleeve, metal, Jurnal bearing (friction bearing)

Tidak besar, aksial

Single

5. Rodagigi buruk atau bersuara

Rendah, ukur kecepatan & percepatan, gunakan accel.

lebih tinggi

A

ditemui f 1x

Tidak stabil, Sangat tinggi, ukur acceleration beberapa kali untuk freq. Rpm, 1x, 2x, 3x, tinggi 4x … 10x… x


GAMBAR SPECTRUM

1 x rpm, seolaholah seperti unbalance Sangat tinggi Jumlah gigi x rpm

Berubahrubah

Tdk tentu

Ditandai timbulnya vibrasi A aksial. Gunakan alat laseralignment. Apabila mesin baru dipasang terjadi vibrasi, maka kemungkinan besar karena misalignment.

Vibrasi akan timbul apabila bearing sdh parah. Gunakan enveloping & shockpulse

A

pd rodagigi vibrasi segaris dengan pusat kontak. pd motor/gen vibrasi hilang bila mesin dimatikan. pd pompa/blower kemungkinan unbalance

A

Awal rusak bersuara, semakin lama keras. Vibrasi biasanya dalam toleransi.

A

f 1x

2x

1x

2x

f 3x

4x

f 1x

f 1x

2x

3x

4x

tooth Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

30


AMPLITUDO

FREKUENSI

6. Gear mesh buruk atau bersuara pada saat start/stop

Rendah, ukur kecepatan &

Sangat tinggi

Tdk

Jumlah gigi x

tentu

percepatan, gunakan accel.

rpm


Tinggi pada aksial

2 x rpm

8. Mechanical Looseness (Pondasi kendor – dudukan lemah/karatan – baut kendor)

Tinggi pada vertikal

9. Mechanical looseness (Pondasi melengkung)

Tinggi pada vertikal, horizontal & aksial

2 x rpm

10. Drive belt buruk

Tdk tentu/berpulsa

1,2,3 atau 4 x rpm belt

Kurang dari 1 x rpm

FASE

KETERANGAN

Sering terjadi pada saat pemasangan

GAMBAR SPECTRUM

A

f 1x


A

Tdk tentu

A

Kencangkan baut Untuk memastikan

2x

3x

4x

f 2x

f <1x


A

1 atau 2 tergantung frekuensi, tdk tetap

A

Biasanya terjadi karena belt tdk berada pada tempatnya secara sempurna.

f 2x

f 1x

2x


3x

4x

31


AMPLITUDO

FREKUENSI

FASE

KETERANGAN

11. Elektrikal

Tidak tinggi, ada suara dengung, lbh terasa bila dimatikan

2 x rpm lebih tinggi daripd

Single/

Vibrasi & suara hilang bila mesin dimatikan

Tinggi pada vertikal atau horizontal

1 x rpm / jml sudu / fan atau impeler x rpm

Tdk tentu

1 x,2 x rpm

Single, double, triple

12. Gaya aerodinamik / hidrolik 13. Gaya reciprocating

Dominan aksial

1 x rpm.

atau lebih

rotate double mark

GAMBAR SPECTRUM

A

f 1x

Lebih terasa bila beban tidak stabil.

2x

A

f 1x

Pada mesin reciprocating bisa ganti desain/isolasi

Jml x

A

f 1x

2x


32

Latihan - 1 A

Roller bearing

PICKUP

A

B

D

Sleeve bearing

Single phase motor LOCATION

5 blade impeller

Peak (mm/s)

FREQ

Peak

FREQ

Peak

FREQ

Peak

FREQ

(cpm)

(mm/s)

(cpm)

(mm/s)

(cpm)

(mm/s)

(cpm)

Vertikal

1.7

1500

0.3

3000

0.05

6000

Horizontal

2.4

1500

0.5

3000

0.05

6000

Aksial

1.2

1500

0.09

3000

0.01

6000

Vertikal

2.1

1500

0.4

3000

0.05

6000

0.08

Variable 37500

Horizontal

3.2

1500

0.7

3000

0.05

6000

0.07

Variable 37500

1500

0.15

3000

0.01

6000

-

-

1500

0.2

3000

0.05

7500

-

-

1500

0.15

3000

0.4

7500

0.4

1400

1500

-

-

-

-

0.45

1400

1500

0.2

3000

0.4

7500

0.25

1400

1500

0.09

3000

0.05

7500

0.30

1400

1500

-

-

-

-

0.42

1400

Vertikal Horizontal Aksial Vertikal D

C

Coupling

Aksial

C

B

Horizontal Aksial

1.9 1.1 1.3 1.2 1.3 1.1 1.5


33

PERTANYAAN : LATIHAN-1 (a) Kemungkinan penyebab apa yang mengakibatkan terjadinya vibrasi 1500 cpm pada bearing A dan B ? (b) Bila kemungkinan penyebabnya lebih dari satu, bagaimana cara Anda 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 tersebut harus ditanggulangi ? Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

34

Latihan - 2 Water turbi ne 12 blades

A

B

Sleeve bearing

PICKUP

A

B

C

D

C

D

Roller bearing

Coupling Generator

LOCATION

DISP

FREQ

DISP

FREQ

DISP

FREQ

DISP

FREQ

Vertikal

2.7

1500

1.2

3000

1.3

4500

1.2

40000

Horizontal

2.8

1500

1.2

3000

1.1

4500

1.3

40000

Aksial

1.3

1500

1.3

3000

0.9

4500

Vertikal

1.8

1500

1.2

3000

1.2

4500

Horizontal

1.9

1500

1.4

3000

1.2

4500

Aksial

1.2

1500

0.9

3000

1.0

4500

Vertikal

1.2

1500

0.9

18000

Horizontal

1.1

1500

1.1

18000

2.0

1300

Aksial

1.1

1500

-

-

2.1

1300

Vertikal

1.2

1500

1.3

18000

2.1

1300

Horizontal

1.3

1500

1.2

18000

2.2

1300

Aksial

1.1

1500

-

-

2.0

1300


35

PERTANYAAN : LATIHAN-2 a) Kemungkinan penyebab apa yang mengakibatkan terjadinya vibrasi 1500 cpm pada bearing A dan B ? b) Bila kemungkinan penyebabnya lebih dari satu, bagaimana cara Anda untuk menemukan penyebab 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 ?


36

Latihan - 3 A

B

1500 rpm Roller bearing

Single phase moto r C

D 3000 rpm

5 blade impeller PICKUP

A

B

C

D

Sleeve bearing

LOCATION

AMPL

FREQ

AMPL

FREQ

AMPL

FREQ

AMPL

FREQ

Vertikal

2.8

1500

1.2

3000

1.3

4500

1.2

40000

Horizontal

2.9

1500

1.2

3000

1.1

4500

1.3

40000

Aksial

2.4

1500

1.3

3000

0.9

4500

Vertikal

4.0

1500

1.2

3000

1.2

4500

Horizontal

4.1

1500

1.4

3000

1.2

4500

Aksial

4.9

1500

0.9

3000

1.0

4500

Vertikal

4.5

3000

0.9

36000

1.9

1300

Horizontal

4.4

3000

1.1

36000

2.0

1300

Aksial

4.8

3000

1.1

36000

2.1

1300

Vertikal

3.8

3000

1.3

36000

2.1

1300

Horizontal

3.9

3000

1.2

36000

2.2

1300

Aksial

3.3

3000

1.1

36000

2.0

1300


37

Latihan - 4 A

B

gearbox

1500 rpm Roller bearing

C

Single phase moto r

D 3000 rpm

compressor

PICKUP

A

B

C

D

Sleeve bearing

LOCATION

AMPL

FREQ

AMPL

FREQ

AMPL

FREQ

AMPL

FREQ

Vertikal

2.8

1500

1.2

3000

1.3

4500

1.2

40000

Horizontal

2.9

1500

1.2

3000

1.1

4500

1.3

40000

Aksial

2.4

1500

1.3

3000

0.9

4500

Vertikal

4.0

1500

1.2

3000

1.2

4500

1.4

24000

Horizontal

4.1

1500

1.4

3000

1.2

4500

1.2

24000

Aksial

4.9

1500

0.9

3000

1.0

4500

1.3

24000

Vertikal

4.5

3000

0.9

36000

1.9

1300

1.2

24000

Horizontal

4.4

3000

1.1

36000

2.0

1300

1.1

24000

Aksial

4.8

3000

1.1

36000

2.1

1300

1.1

24000

Vertikal

3.8

3000

1.3

36000

2.1

1300

Horizontal

3.9

3000

1.2

36000

2.2

1300

Aksial

3.3

3000

1.1

36000

2.0

1300


38

Machine Signal Types Semi Static • Shaft Position

Harmonic

•Imbalance •Misalignment

Modulated • Torsional Load • Tooth Fatigue • Eccentricity

1X

2X

200Hz

1X

5 kHz

1X

10 kHz

1X

10 kHz

Random

•Lubrication Problems • Rolling Element (RE) Bearing Mounting defect • Flow Exited

Pulsed

Time

• RE Bearing Wear • Rubs • Blade Damage, fouling • Surge, Cavitation, • Local Tooth Defects

Frequency


39

Penyebab vibrasi dan frekuensi karakteristiknya Possible cause Unbalance

Dominant Frequency 1x rotation frequency

Misalignment; bent shaft Bearing damage

multiples High frequency vibration, Shock pulse vibration

1x rotation frequency

Amplitude proportional to unbalance and RPM; caused by displacement of rotation axis from mass center of gravity Severe axial vibration and 2nd harmonic; best

often 2x and higher

axial

realigned with ROTALIGN©, OPTALIGN© V or SYSTEM

Subharmonic, exactly 1/2 or 1/3 of rotation frequency Oil film whirl 40% - 50% of rotation or whip (sleeve frequency bearings) Hysteresis Critical shaft rotation whirl frequency

Belt drive damage Turbulenc e; cavitation Electric ally induced vibration Frequency alternator signal

Comments

Radial for dynamic imbalance, possibly axial Radial and

Sleeve bearing play

Gear tooth damage

Direction

Radial and axial Radial

2 TURBALIGN© May be diagnosed from vibration only through use of diagnostic functions, shock pulse analysis or envelope curve analysis. Usually dependent upon RPM and operating temperature.

Radial

Occurs with high-speed machines; phase fluctuates.

Radial

Vibrations are excited as machine climbs through critical RPM and remain at higher speeds. Remedy : Rotor must be reworked (mounting improved). Sidebands oc cur from modulation of tooth mes h vibration at rotation frequency; may be isolated using envelope analysis.

Toot h mes h frequenc y and multiples thereof with sidebands located at multiples of rotation frequency Rotation frequency and multiples thereof Blade/ vane pas sing frequency Rotation frequenc y, 2x line frequency

Radial and axial

Multiples of motor line frequency

Radial

Radial Radial and axial Radial and axial

Additionally recommended : combined RPM and belt speed measurements to check for belt slippage. Additionaly rec ommended for pumps : s hock puls e measurement at the pump housing. Sidebands may also oc cur located at multiples of the rotation frequency; vibration ceases when power is cut off. Disappears in direct line operation; proportional to motor line frequency.


40

Contoh lapangan : Sifter


41

Spectra frekuensi dari Sifter


42

Contoh no. 2 : Turbocompressor

Tidak lama sebelum perbaikan total

Tidak lama setelah perbaikan total


43

Contoh no. 3 : Foundry Fan


44

Contoh no. 4 : Tunnel Furnace Fan


45

Contoh : Pompa centrifugal


46

Machine Vibration Example 1 Misalignment

Unbalance

f n

f n

Machine spectru m:

Machine spectrum:

v [mm/s]

v [mm/s]

f n

Symptom : High Amplitude at f n RPM [Rev/min] • Fundamental Freq. Fn = 60 •

f n

f [Hz]

Evaluation criteria:ISO 10816-3

2xf n

f [Hz]

Symptom : Increased amplitude visible at f n and/ or 2 •

First and Second order of rotor frequency

•

Radial : parallel misalignment axial : angular misalignment


47

Machine Vibration Example 2 Cracked / Broken Tooth

Gear mesh fault s

f n1

z2

f n1

f n2

z1

z1

z2

f n2 a mm/s²

Machine Spectrum :

f z

2xf z

3xf z

4xf z

a mm/s²

Machin e Spectrum:

f z

f (Hz)

Symptom : Harmonics of f z visible • Gear mesh frequency f z = f n1. Z1 = f n2. Z2 • Z, Z2 : number of gear teeth

2xf z

3xf z

f (Hz)

Symptom : Side bands with f n •

Side band distance f n is the fundamental frequency of the defective gear (broken tooth)

many side bands around f z gear mesh with slowly • f frequency driven shaft decreased amplitudes n1 : rotational Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 48 •

Machine Vibration Example 3 Bad foundation

Turbulences s=9

f n

f n x=3 (e.g. fixtur e for bearing)

v mm/s

Machine spectr um:

f n

2xf n

3xf n

4xf n

v mm/s

f (Hz)

Symptom : Harmonics of f n are visible RPM [Rev/min] fundamental freq. f = n • 60 •

Root Cause:

Resonance or Instability

Machine spectru m:

f n

f BPF

x ∗ f BPF f (Hz)

Symptom : Blade pass frequency f BPF •

Blade pass frequency f BPF = f n . s

•

Higher orders x*f BPF = f n . s . x s: number of blades x: number of disturbance locations

• •


49

Machine Vibration Example 4 Resonance

b) Bode diagram in coast dow n v mm/s Resonance step-up

f n nRes. n in Rev/min ϕ

(°)

a) Machine spectrum V mm/s

Phase shift of 180°

nRes.

n in Rev/min

c) Waterfall diagram veloci ty spectra in coast dow n f n

2xf n

3xf n

4xf n

5xf n

f (Hz)

Symptom : Harmonics of f n visible preferably uneven multiples •

v mm/s

f n

2xf n

3xf n Resonance step-up

RPM [Rev/min] fundamental freq. f n = 60 f (Hz) Natural frequency n (Rev/min) Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

50

BEARING CONDITION MEASUREMENT

Productive Maintenance Technology


51

Monitoring Techniques Types of Bearings

Journal Journal Bearings Bearings

••Stationary StationarySignals Signals ••Relative RelativeLow LowFrequency Frequency ••Displacement Displacementtransducer t ransducer

Use Proximity probes Rolling Rolling Element Element Bearings Bearings ••Modulated ModulatedRandom RandomNoise Noise ••Pulsating Pulsatingsignals signals ••High HighFrequency Frequency •• Accelerometers Accelerometers

Use Accelerometers


52

Forces and Motions in Rolling Bearings bearing clearance

VIR > VRE > VOR > VRC

Example: C3 bearing type 62222

f IR > f RE > f OR > f RC

C3 = 0.05 mm gap

Vc Fcentrifugal, rolling element Vb

v(f n)

housing

Fdyn., rotor

shaft Fstat, rotor acceleration impulse roller leaves load zone

Hertz surface pressure

breaking impulse roller enters load zone vibration

load zone = measuring zone contact no air gap Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

53

A Typical Bearing Life Cycle


54

Types of Rolling Bearing Damages (1) Damages types/ Causes 1 Wear

wear

- lifetime expired - overloading - assembly / manufacturing error - greasing deficiency

shock pul ses

wear

2 Damage to rolling tr ack

3 Contaminated lubricant

-

lifetime expired bearing overloaded bearing under-loaded greasing deficiency

- Damaged rolling track - damaged sealing - contaminated lubricant

shock pul ses damage envelope

high variation in shock pu lse levels and defect frequencies


55

Types of Rolling Bearing Damages (2) Damages types/ Causes 4 Greasing deficiency

- greasing deficiency - Under-loading temperature rises very late

shock pulses air gap

5 Unround deformation o f bearing race

- assembly error - manufacturing defect in shaft or bearing housing

damage frequencies in envelope

dirt

6 Jammed lo ose bearing

- in bearing housing (sliding fit) - mis-calculation of housing design fixed bearing

loose bearing

high vibration incr easing bearing Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 temperature 56

Types of Rolling Bearing Damages (3) Damages types/ Causes 7 Excessive Greasing

8 Installed at an angle

- maintenance error (quantity, interval) - defective grease grease drain

- assembly error

- assembly error at

9 Rolling bearing bearing with taper sleeve clearance too small - shaft diameter to large to

Large temperature Increase after greasing

Whistling Bearing noise

Large temperature increase after greasing deficiency

inner race diameter - got hot by friction after greasing deficiency


57

Types of Rolling Bearing Measurement Methods

k (t) Method

?

Spike Energy Value BCU Value

?

Kurtosis Factor gSE - Factor SEE Factor Acceleration Crest Factor Shock pulse measurement Normalising • Alarm Levels • Gradient of t rend development is necessary for evaluation of rolli ng bearing condition •


58

Normalising of Shock Values dBsv 90

dBsv 90 ideal measurement dBn

measurement location with signal damping

dBm dBm dBc dBc

dBi 0

0 dBia

-9

-9 dBsv = absolute shock pulse value dBn = normalised shock pulse value

dB i = initial value dBia = (f(φ, rpm) dBi = (f(φ, rpm) dB ia = adjus ted initi al value • Basic normalised shock pulse value • Actual measurement location dBn = dBsv – dBia • function of RPM and shaft diameter dBn = dBsv – dBi (not at load zone) • influencing factors like load condition dBia = dBi + dBa lubrication andAG, bearing type– PART 2 Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik Germany 59 Where dB (dB) is

Normalising of Shock Pulse Measurements


60

Extent of rolling bearing surface damage

0 good

d

n - number of rolling elements in contact with damage b a - extent of damage to rolling bearing component

1 very small

2 small

at ac

- small material defects - several pitting - defect frequencies are visible in envelope spectrum

- slight material splintering - Max values of shock pulses begin to rise when rolling element passes over defect


61

Extent of rolling bearing surface damage

3 medium

4 large

5 very large

- 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 dramatically carpet values rise continuously

- carpet values rise substantially - bearing approaching crash - components may break - increasing machine vibrations - rotor drops into very large depression - several rollers drop into severe


62

ENVELOPE ANALYSIS

Productive Maintenance Technology


63

Envelope Analysis – Rolling Bearings Fault Detection Time signal: a m/s2

No rolling track defect: t (s)

Rectification a m/s2

t (s)

Enveloping a m/s2

a m/s2

Envelope spectrum:

Envelope

t (s) f (Hz) Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2

64

Envelope Analysis – Rolling Bearings Fault Detection Time sig nal: a m/s2

Rolling track defect: t (s)

a m/s2

Rectification

t (s)

Enveloping

Envelope spectrum:

a 2 m/s

a m/s2 Envelope t (s)

Defect frequency f RPO 2• f RPO 3• f RPO 4•f RPO F

F

F

1

Copyright 2004- PT. Putranata Adi Mandiri – sole agent Prüftechnik AG, Germany –(Hz) PART 2 = • f RPOF

T

f (Hz)

F

65

Roller Bearing Race Track Defects Outer Race Defect :

a m/s²

Inner Race Defect:

a m/s²

Envelope Spectrum:

f RPOF2f RPOF3f RPOF4f RPOF5f RPOF

f RPIF

f (Hz)

2xf RPIF

f (Hz)

Rolling element pass inner race frequency f RPIF and many side bands with interval f n

Rolling element pass outer race f RPOF and harmonics clearly visible if only f RPOF appears, then it can also be an unround deformation of the outer race track

Envelope Spectrum :

Modulated with the fundamental frequency f n as the inner race defect runs periodically through the load zone with f n • In the case of very big unbalance, side bands with interval • Fundamental modulation frequency f n and harmonics are f n appear because of periodic load changes visible (in the load zone modulation with f n as the unbalance runs Copyright 2004Adi Mandiri – sole agent Prüftechnik AG, Germany – PART 2 66 periodically through the PT. loadPutranata zone) •

•

VIBRASI LEVEL 2

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