Typical Steps of field Balancing Illustration with model Telephone: Fax: Balancing Training Part 1

1. Collecting Machine data 2. Preparing Instrument & Sensor 3. Balancing really required ? 4. Balancing possible ? 5. Procedure of balancing An Overview of the Steps

Step 1 - Collecting Machine data Understand the machine to be balanced as much as possible Collect machine data Take a photo of the machine

Sample: Machine to be balanced Impeller Parameter: Diameter: 1400mm Thickness: 500mm Blade Number: 12 Material:Fiberglass-Reinforced Plastics RPM: 1825 r/min Bearing Model: ? Motor Parameter: Power: 75kW RPM: 1500 r/min Others: Belt transmission Spring base Manufacture: LG Impeller Bearing1 Bearing2 Motor

Step 2 - Preparing Instrument & Sensors Sendig-904/907 dual-channel data collector/analyser/balancer A notebook computer Sendig-MCM3 Analysis Software

Sensors & Cable connecting Attach reflecting paper on shaft

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

6: Point: Motor-1-Side-2-X Alarm-mode: Displacement Freq-Range: 500Hz Sensor:4.6 ………………………… New Data Old Data ACCxxx / xxx m/s 2 VEL7.2 / 2.1 mm/s DISP68 / 12 µm ENV xx / xx m/s 2 Horizontal VELOCITY is the critical parameter

Comparison with ISO2372

Overall Value Measurement Acc. Vel. Disp. Envelope Peak ms -2 RMS mm/s P_P um RMS ms -2 Hor Ver Sample

Measurement 9.95 mm/s Not Permissible, Balancing really required ! Sample

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

Sample of non-single peak spectrum- not suitable for Balancing

Sample of non-single peak spectrum- Better change bearing before balancing

Sample of single peak spectrum – You can reduce the vibration by Balancing

Step 4-2: Balancing possible ? – “ 90 o phase difference ” ? Use 904/907 to measure vibration phase difference between vertical and horizontal directions Only “90 o phase difference” can go for balancing 1) switch to balancer and use 2-planes balancing procedure 2) Page down to “ Initial Measurement ” to measure vibration phase at X & Y 3) See if “ 90 o phase difference ” exist?

Phase Measurement: Velocity Amplitude Phase Vertical: Horizontal: Since phase difference is not 90 o nor closer to 90 o, this means the problem with the fan is something else other than unbalance. Phase difference not 90 o Sample Sample of “non-90 o phase difference” – You cannot reduce the vibration by Balancing

1. Phase stable 2. Phase Measurement: Velocity Amplitude Phase Vertical: Horizontal: ? Phase difference is 77 o Sample Sample of nearly “90 o phase difference” – You can reduce the vibration by Balancing

Procedure of balancing Balancing Training Part 2

Different Kinds Of Imbalance 1-plane imbalance 2-plane imbalance

Characteristics Of Imbalance 1. The vibration frequency is mainly composed of RPM frequency. For each round the rotor turns, a vibration is occurred. 2. The wave is an approximate sine wave. 3. There is a difference of 90 o between the vertical vibration phase and the horizontal one. 4. With RPM increasing, the vibration amplitude is increased

Basic Principle Of 1 Plane Balancing amplitude phase RPM A 1 select a plane to fix trial mass and a point to measure, draw scale of phase and sign of 0 o phase 2 measure initial vibration A 0 (phase and amplitude) 3 fix a trial mass Q on the plane, measure vibration A 1 4 calculate influence coefficients: 5 calculate balancing mass P:

Illustration of 1 Plane Balancing A0A0 A1A1 A 1 - A 0 o  draw A 0 & A 1, calculate A 1 - A 0 measure the angle  between A 1 - A 0 and A 0 turn Q a  along the direction of , gain the correct location of balancing mass. the weight of balancing mass is as the following :   K o Q P

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

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

NOTICES DURING THE OPERATION Confirm the dynamic balancing are needed according to spectrum and phase analysis. Direction of phase: reverse to the direction of rotation Reflecting slice phase

SELECTING PARAMETERS Measure displacement or velocity for middle or low speed machines Measure velocity or acceleration for high speed machines

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

1-PLANE BALANCING Without influence coefficients 907 A Tacho sensor Accelerometer

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

Always make sure the “ Setting ” is correct before the balancing Enter 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)

INITIAL MEASUREMENT Press Enter to measure rotation speed first Press Enter for a moment to measure vibration after rotation speed become steady After phase and amplitude become steady, press Enter for a moment to end the measurement

TRIAL ESTIMATION Input the 4 parameters When cursor on 6th line, press Enter to calculate trial range Stop the machine, fix a trial mass according to the range

TRIAL MEASUREMENT Input phase and weight of the trial, confirm whether it will be removed afterward, restart the machine Move cursor to 6th line, press Enter to measure rotation speed When RPM steady, press Enter a moment to measure vibration When amplitude and phase steady, press Enter for a moment to end the measurement

TRIAL RESULT See what the 6 th line shows If YES displayed, press Pg Dn to go on If NO displayed, stop the machine, adjust trial mass, return to the early page of TRAIL MEASUREMENT, measure again

CALCULATION Cursor on 2 nd line, press ENTER to calculate influence coefficients The result is shown in 4 th line Cursor on 2nd line, press Enter to calculate balancing mass The result is shown in 3 rd line

Decomposing/Splitting Input the 2 angles Display the results If nothing displayed at right side, change the order of the 2 angles and re-enter Pa Pa1 Pa2

VERIFICATION Cursor on 2nd line, press Enter to measure rotation speed When RPM steady, press Enter a moment to measure vibration When amplitude and phase steady, press Enter for a moment to end the measurement The last 2 lines displays the results

1-PLANE BALANCING With influence coefficients, you do not need to add trial mass. You need only measure the initial vibration

SETTING PARAMETERS Set “Yes” for the question of “Have influence Coefficient?”

INITIAL MEASUREMENT Press Enter to measure rotation speed Press Enter for a moment to measure vibration after rotation speed become steady When phase and amplitude become steady, press Enter for a moment to end the measurement

INPUT COEFFICIENTS Move the cursor to the 4th line, input amplitude and angle of coefficient Press Pg Dn to the next page

Calculation, Decomposition & verification calculate balancing mass Decomposition and verification are the same as illustrated earlier Pa Pa1 Pa2

2-PLANES BALANCING Without influence coefficients The main difference than 1-plane: 1. Need to add trial mass one after another at the 1 st plane and 2 nd plane 2. Need to use 2 vibration sensors

Sensors & Cable connecting Attach reflecting paper on shaft

SETTING PARAMETERS

INITIAL MEASUREMENT & TRIAL ESTIMATION Get 2 lines of reading here

TRIAL I MEASUREMENT Input phase and weight of the trial on plane 1, decide if it will be removed, restart the machine

TRIAL II MEASUREMENT Input phase and weight of the trial on plane 2, decide if it will be removed, restart the machine

Calculation, Decomposition & Verification calculate balancing mass Decomposition and verification are the same as illustrated earlier Pa Pa1 Pa2 Pb Pb1 Pb2

2-PLANES BALANCING With influence coefficients With influence coefficients, you do not need to add trial mass. You need only measure the initial vibration.