ISO 21940-21:2022

INTERNATIONAL ISO
STANDARD 21940-21
Second edition
2022-11
Mechanical vibration — Rotor
balancing —
Part 21:
Description and evaluation of
balancing machines
Vibrations mécaniques — Équilibrage des rotors —
Partie 21: Description et évaluation des machines à équilibrer
Reference number
© ISO 2022
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Published in Switzerland
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Contents Page
Foreword . vi
Introduction .vii
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Capacity and performance data of the balancing machine . 1
4.1 General . 1
4.2 Data for horizontal balancing machines . 1
4.2.1 Rotor mass and unbalance limitations . 1
4.2.2 Production efficiency . 2
4.2.3 Rotor dimensions . 3
4.2.4 Balancing machine drive data . 4
4.2.5 Torque . 4
4.2.6 Type of rotor drive . 5
4.2.7 Brake . 5
4.2.8 Motor and controls . 5
4.2.9 Speed regulation . . 5
4.2.10 Couple moment interference ratio, I . 5
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4.2.11 Air pressure requirements . 5
4.3 Data for vertical balancing machines . 5
4.3.1 Rotor mass and unbalance limitations . 5
4.3.2 Production efficiency . 6
4.3.3 Rotor dimensions . 6
4.3.4 Balancing machine drive data . 8
4.3.5 Torque . 8
4.3.6 Type of drive to rotor . 8
4.3.7 Brake . 8
4.3.8 Motor and controls . 8
4.3.9 Speed regulation . 8
4.3.10 Couple moment interference ratio . 8
4.3.11 Air pressure requirements . 8
5 Machine features . 8
5.1 Principle of operation . 8
5.2 Machine arrangement . 8
5.3 Measuring system . 9
5.3.1 General . 9
5.3.2 Unbalance indicators . 9
5.3.3 Additional features . 9
5.3.4 Operation of the indicating system . . 10
5.4 Plane separation system . 10
5.4.1 Multi-plane balancing machines. 10
5.4.2 Single-plane horizontal or vertical balancing machines . 10
5.5 Setting and calibration of the measuring system . 10
5.5.1 General . 10
5.5.2 Soft-bearing machines . 11
5.5.3 Hard-bearing machines . 11
6 Production efficiency .11
6.1 General . 11
6.2 Time per balance cycle .12
6.3 Unbalance reduction ratio, R . 13
UR
7 Performance qualifying factors . .14
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8 Installation requirements .14
8.1 General . 14
8.2 Supply requirements . 14
8.3 Foundation . 15
9 Proving rotors and test masses . .15
9.1 General . 15
9.2 Standardized proving rotors . 15
9.3 User defined proving rotors . 17
9.4 Test masses . 17
9.4.1 General . 17
9.4.2 U test masses . 24
mar
9.4.3 R test masses . 25
UR
9.4.4 Permissible test mass errors . 26
9.4.5 Material. 27
10 Balance machine verification tests .27
10.1 General . 27
10.2 Requirements for evaluating balance machine performance .28
10.3 Test speed .29
10.4 Test for establishing the minimum achievable residual unbalance, U .29
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10.4.1 General .29
10.4.2 Initial balancing machine setting .29
10.4.3 Unbalance added . 31
10.4.4 Readings .
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