ISO INTERNATIONAL STANDARD 21940-11 First edition 2016-11-15 Mechanical vibration Rotor balancing - Part 11: Procedures and tolerances for rotors with rigid behaviour Vibrations meécaniques - Equilibrage des rotors - Partie 11: Modes operatoires et tolérances pour rotors a comportement rigide Reference number IS0 21940-11:2016(E) ISO @ IS0 2016 Bodies Not for Resale, 02/15/2017 19:28:05 MST IS0 21940-11:2016(E) COPYRIGHTPROTECTEDDOCUMENT IS0 2016, Published in Switzerland 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 @ IS0 2016 - All rights reserved rds Bodies Not for Resale, 02/15/2017 19:28:05 MST IS0 21940-11:2016(E) Contents Page Foreword ..V Introduction. ...vi 1 Scope. 2 Normative references 3 Terms and definitions 4 Pertinent aspects of balancing 4.1 General .1 4.2 Representation of the unbalance ..1 4.3 Unbalance effects .2 4.4 Referenceplanes for unbalance tolerances 4.5 Correction planes 4 4.5.1 General. ..4 4.5.2 Rotors which need onecorrection plane only .4 4.5.3 Rotors which need two correction planes ..4 4.5.4 Rotors with more than two correction planes 4 4.6 Permissible residual unbalance .4 5 Similarity considerations .5 5.1 General .5 5.2 Permissible residual unbalance and rotor mass .5 5.3 Permissible residual specific unbalance and service speed Specification of unbalance tolerances .6 6 6.1 General. ..6 6.2 Derivation of the unbalance tolerances. 6.3 Balance quality grade G. 1 6.3.1 Classification 6.3.2 Special designs. 7 6.3.3 Permissible residual unbalance. ..10 6.4 Experimental evaluation .10 6.5 Unbalance tolerances based on bearing forces or vibrations .10 6.5.1 Bearing forces.. ..10 6.5.2 Vibrations. .11 6.6 Methods based on established experience ..11 7 Allocation of permissible residual unbalance to tolerance planes .11 7.1 Single plane .11 7.2 Two planes. ..11 7.2.1 General ..11 7.2.2 Limitations for inboard rotors. 7.2.3 Limitations for outboard rotors. .12 8 Allocation of unbalance tolerances to correction planes ..13 8.1 General. ..13 8.2 Single plane ..14 8.3 Two planes. ..14 9 Assembled rotors. .14 9.1 General ..14 9.2 Balanced as a unit. ..14 9.3 Balanced on component level ..14 10 Accounting for errors in the verification of permissible residual unbalances ..15 10.1 General ..15 10.2 Unbalance tolerance .15 10.3 Combined error of unbalance measurements .15 opyrtneatonal rights reerved iii nsewithvarious National Stan Not for Resale, 02/15/2017 19:28:05 MST