how to do field balancing by 904 or 907
TRANSCRIPT
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Typical Steps of field Balancing
Illustration with model 907
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http://www.sendig.com
Balancing Training Part 1
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1. Collecting Machine data
2. Preparing Instrument & Sensor3. Balancing really required ?
4. Balancing possible ?5. Procedure of balancing
An Overview of the Steps
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Step 1 - Collecting Machine data Understand the machine to be balanced
as much as possible
Collect machine data
Take a photo of the machine
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Sample: Machine to be balanced
Impeller Parameter:
Diameter: 1400mm Thickness: 500mm
Blade Number: 12
Material:Fiberglass-Reinforced
Plastics
RPM: 1825 r/min
Bearing Model: ?
MotorParameter:
Power: 75kW
RPM: 1500 r/minOthers:
Belt transmission
Spring base
Manufacture: LG
Impeller
Bearing1 Bearing2
Motor
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Step 2 - Preparing Instrument & Sensors
Sendig-904/907 dual-channel datacollector/analyser/balancer
A notebook computer Sendig-MCM3 Analysis Software
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Sensors & Cable connecting
Attach reflectingpaper on shaft
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Step 3 - Balancing really required? Use 904/907 to measure overall vibration values
Compare with ISO Standard
1) Switch
to Analyzer
2) Use Collector to
measure vibration
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6: Point: Motor-1-Side-2-XAlarm-mode: DisplacementFreq-Range: 500Hz
Sensor:4.6
New Data Old Data ACC xxx / xxx m/s2
VEL 7.2 / 2.1 mm/sDISP 68 / 12 m
ENV xx / xx m/s2
Horizontal VELOCITY is the critical parameter
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Comparison with ISO2372
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Overall Value Measurement
Acc. Vel. Disp. EnvelopePeak ms-2 RMS mm/s P_P um RMS ms-2
Hor. 88.81 9.95 101.5 5.268
Ver. 55.89 5.554 38.77 7.362
Sample
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Measurement
9.95 mm/s
Not Permissible, Balancing really required !
Sample
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Step 4-1: Balancing possible?single peak spectrum?
Use 904/907 to measure vibration spectrum
Only single peak spectrum can go for balancing
1) Switch
to Analyzer
2) Use Collector to
measure vibration
3) Use C-Spect to
see velocity spectrum
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Sample of non-single peak spectrum- not suitable for Balancing
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Sample of non-single peak spectrum- Better change bearing before balancing
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Sample of single peak spectrumYou can reduce the vibration by Balancing
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Step 4-2: Balancing possible ?90o phase difference?
Use 904/907 to measure vibration phase difference betweenvertical and horizontal directions
Only 90ophase difference can go for balancing
1) switch to balancerand use 2-planes
balancing procedure
2) Page down to InitialMeasurement to measure
vibration phase at X & Y
3) See if90o phase difference exist?
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Phase Measurement:
Velocity Amplitude Phase
Vertical: 9.416 320
Horizontal: 3.08 116
Since phase difference is not 90o nor closer to 90o ,this means the
problem with the fan is something else other than unbalance.
Phase
difference
not 90o
SampleSample of non-90ophase difference
You cannot reduce the vibration by Balancing
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1. Phase stable
2. Phase Measurement:
Velocity Amplitude Phase
Vertical: 0.693 73
Horizontal: 1.569 150
?
Phasedifference is
77o
SampleSample of nearly 90ophase difference
You can reduce the vibration by Balancing
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Procedure of balancing
Balancing Training Part 2
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Different Kinds Of
Imbalance1-plane
imbalance2-plane
imbalance
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Characteristics Of
Imbalance
1. The vibration frequency is mainly composed of
RPM frequency. For each round the rotor turns, avibration is occurred.
2. The wave is an approximate sine wave.
3. There is a difference of 90o between the vertical
vibration phase and the horizontal one.
4. With RPM increasing, the vibration amplitude is
increased
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Basic PrincipleOf 1 Plane Balancing
Q
AA01
0AP
amplitude phase RPM
A
1 select a plane to fix trial mass and a
point to measure, draw scale of phase
and sign of 0o phase
2 measure initial vibrationA0(phase
and amplitude)
3 fix a trial mass Q on the plane,
measure vibrationA1
4 calculate influence coefficients:
5 calculate balancing massP:
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Illustration of 1 Plane Balancing
A0A1
A1- A0
o
drawA0 &A1, calculateA1-A0
measure the angle betweenA1-A0andA0
turn Q aalong the direction of ,gain the correct location of balancingmass.
the weight of balancing mass is asthe following :
Ko
QP
01
0
AA
AQP
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Method of Influence
Coefficients Method of influence coefficients is
widely used, its step as the following
(1 plane balancing as example):
1 measure initial vibration
2 fix a trial mass
3 measure the vibration with the trial mass
4 calculate the result of balancing mass
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IF THE INFLUENCE COEFFICIENTS ARE KNOWN, THE
STEP OF FIXING TRIAL MASS ARE IGNORED
The former steps are simplified as the following:
1) measure initial measurement
2) input influence coefficients
3) calculate the result of balancing mass
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NOTICES DURING THE OPERATION
Confirm the dynamic
balancing are neededaccording to spectrum
and phase analysis.
Direction of phase:reverse to the
direction of rotation
Reflecting slice
phase
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SELECTING PARAMETERS
Measure displacement or velocity formiddle or low speed machines
Measure velocity or acceleration for highspeed machines
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CONFIRM whether the trial is suitable
The radius of loading trial mass is as same as loading
the amended mass
The turning speed is steady
beforeandaftertrialvaluedifference25%
phasedifference25okok
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1-PLANE BALANCING
Withoutinfluencecoefficients
907
A
Tachosensor
Accelerometer
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Operation Basic Prompt is displayed at the last line
Press and key to move the
cursor up and down
Press Enter to select iterm
Press number keys to input digits
To other MENU, press PgDn or
PgUp
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Always make sure the Setting
is correct before the balancingEnter a digit, select 1 set of data from 10
Enter a digit, select plan number
Change by ENTER,
use displacement or velocity
for most machines
Input sensitivity (from
accelerometer certificate)
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INITIAL MEASUREMENT Press Enter to measure
rotation speed first
Press Enter for a momentto measure vibration afterrotation speed becomesteady
After phase and amplitudebecome steady, pressEnter for a moment to endthe measurement
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TRIAL ESTIMATION Input the 4
parameters
When cursor on 6thline, press Enter tocalculate trial range
Stop the machine, fixa trial mass accordingto the range
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TRIAL MEASUREMENT Input phase and weight of the
trial, confirm whether it will beremoved afterward, restart themachine
Move cursor to 6th line, pressEnter to measure rotation speed
When RPM steady, press Enter a
moment to measure vibration When amplitude and phase
steady, press Enter for amoment to end themeasurement
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TRIAL RESULT See what the 6th line
shows
If YES displayed, pressPg Dn to go on
If NO displayed, stopthe machine, adjust
trial mass, return to theearly page of TRAILMEASUREMENT,measure again
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CALCULATION
Cursor on 2nd line, pressENTER to calculate influencecoefficients
The result is shown in 4th line
Cursor on 2nd line, pressEnter to calculate balancingmass
The result is shown in 3rd line
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Decomposing/Splitting Input the 2 angles
Display the results
If nothing displayed atright side, change theorder of the 2 anglesand re-enter
Pa
Pa1
Pa2
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VERIFICATION Cursor on 2nd line, press Enter
to measure rotation speed
When RPM steady, press Entera moment to measurevibration
When amplitude and phase
steady, press Enter for amoment to end themeasurement
The last 2 lines displays theresults
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1-PLANE BALANCINGWith influence coefficients,
you do not need to add trial
mass. You need only
measure the initial vibration
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SETTING PARAMETERS
Set Yes for the question
of Have influence
Coefficient?
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INITIAL MEASUREMENT Press Enter to measure
rotation speed
Press Enter for a momentto measure vibration afterrotation speed becomesteady
When phase and amplitudebecome steady, pressEnter for a moment to endthe measurement
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INPUT COEFFICIENTS
Move the cursor to the
4th line, inputamplitude and angle ofcoefficient
Press Pg Dn to the nextpage
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Calculation, Decomposition &
verification
calculate
balancing mass
Decomposition
and verification
are the same as
illustrated earlier
Pa
Pa1
Pa2
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2-PLANES BALANCING
Without influence coefficients
The main difference than 1-plane:
1. Need to add trial mass one after
another at the 1st plane and 2nd
plane
2. Need to use 2 vibration sensors
Sensors & Cable connecting
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g
Attach reflectingpaper on shaft
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SETTING PARAMETERS
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INITIAL MEASUREMENT & TRIAL
ESTIMATION
Get 2
lines of
reading
here
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TRIAL I MEASUREMENT Input phase
and weight of
the trial onplane 1,decide if it willbe removed,restart themachine
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TRIAL II MEASUREMENT Input phase
and weight of
the trial onplane 2,decide if it willbe removed,restart themachine
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Calculation, Decomposition &
Verification
calculate
balancing mass
Decomposition
and verification
are the same
as illustrated
earlier
Pa
Pa2
Pb Pb1
Pb2
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2-PLANES BALANCING With
influence coefficients
With influence coefficients,
you do not need to add trialmass. You need only
measure the initial vibration.