ISO INTERNATIONAL STANDARD 21940-12 First edition 2016-04-01 Mechanical vibration Rotor balancing - Part 12: Procedures and tolerances for rotors with flexible behaviour Vibrations mécaniques - Equilibrage des rotors - Partie 12: Modes opératoires et tolerances pour les rotors a comportementflexible Reference number IS0 21940-12:2016(E) ISO International Organization for Standardization @ IS0 2016 ZHEJIANG INSTOFSTANDARDIZATION C15956617 ed without license from IHS IS0 21940-12:2016(E) COPYRIGHTPROTECTEDDOCUMENT IS02016,PublishedinSwitzerland All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISO's member body in the country of the requester. ISO copyrightoffice Ch. de Blandonnet 8 . CP 401 CH-1214 Vernier, Geneva, Switzerland Tel. +41 22 749 01 11 Fax +41 22 749 09 47 [email protected] www.iso.org Intenationaibr PrganizationforStandardization icensee-ZHEJIANG INST OF STANDARDIZoISQ s.6 - All rights reserved etworking permitted without license from IHS IS0 21940-12:2016(E) Contents Page Foreword ..V Introduction. ..vii 1 Scope. 2 Normative references 3 Terms and definitions 4 Fundamentals of dynamics and balancing of rotors with flexible behaviour. .2 4.1 General 2 .2 4.2 Unbalance distribution. 4.3 Mode shapes of rotors with flexible behaviour . 2 4.4 Response of a rotor with flexible behaviour to unbalance. 4.5 Aims of balancing rotors with flexible behaviour. 4 4.6 Provision for correction planes. 4.7 Coupled rotors. ..5 5 Rotor configurations.. ..5 6 Procedures for balancing rotors with flexible behaviour at low speed .7 6.1 General 6.2 Selection of correction planes. ..8 6.3 Service speed of the rotor. .8 6.4 Initial unbalance. 6.5 Low-speed balancing procedures. .8 Procedure A - Single-plane balancing. .8 6.5.1 6.5.2 Procedure B - Two-plane balancing ..8 6.5.3 Procedure C- Individual component balancing prior to assembly 6.5.4 Procedure D - Balancing subsequent to controlling initial unbalance .9 6.5.5 Procedure E Balancing in stages during assembly 6.5.6 Procedure F Balancing in optimum planes. ..10 7 Procedures for balancing rotors with flexible behaviour at high speed ..10 7.1 General. .10 7.2 Installation for balancing .10 7.3 ProcedureG - Multiple speed balancing ..11 7.3.1 General ..11 7.3.2 Initial low-speed balancing .11 7.3.3 General procedure. ..11 7.4 ProcedureH - Service speed balancing .13 7.5 Procedure I - Fixed speed balancing. ..14 7.5.1 General. ..14 7.5.2 Procedure. ..14 8 Evaluation criteria ..14 8.1 Choice of criteria .14 8.2 Vibration limits in the balancing machine .15 8.2.1 Overview ..15 8.2.2 General. .15 8.2.3 Special cases and exceptions .15 8.2.4 Factors influencing machine vibration .15 8.2.5 Critical clearances and complex machine systems. ..16 8.2.6 Permissible vibrations in the balancing machine ..16 8.3 Residual unbalance tolerances. ..17 8.3.1 Overview. ..17 8.3.2 General. ..17 8.3.3 Limits for low-speed balancing .17 8.3.4 Limits for multiple speed balancing ..18 iii nsee=ZHEJIANG INST OF STANDARDIZATION C1 5956617 ed without license from IHS Not for Resale, 2016/6/2 08:53:00