Beginner's Guide to Machine Vibration Revision 28/06/06 COPYRIGHT © 1999, 2006 Commtest Instruments Ltd. All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of Commtest Instruments Ltd. For information, contact: Commtest Instruments Ltd 28-b Moorhouse Avenue Christchurch New Zealand E-mail
[email protected] Printed in New Zealand. Disclaimer Information in this document is subject to change without notice. Names and data used in examples are fictitious unless otherwise noted. This document is distributed as is, without warranty of any kind, either expressed or implied, respecting the contents of this document, including but not limited to implied warranties for the document’s quality, performance, merchantability, or fitness for any particular purpose. Neither Commtest Instruments Ltd nor its employees, dealers, or distributors shall be liable to the user of this document or any other person or entity with respect to any liability, loss, or damage caused or alleged to be caused directly or indirectly by this document. Trademark Notice vb™ and PROFLASH™ are trademarks of Commtest Instruments Ltd. vbSeries® and Ascent® are registered trademarks of Commtest Instruments Ltd. Other trademarks and registered trademarks belong to their respective owners. ii Contents Foreword....................................................................... 1 Section 1: Why is Monitoring Vibration Important?.. 2 What is Machine Vibration? ..................................................... 3 What Causes Machine Vibration?............................................ 5 (a) Repeating Forces ...................................................................5 (b) Looseness ..............................................................................7 (c) Resonance..............................................................................8 Why Monitor Machine Vibration? ........................................... 10 (a) Severe Machine Damage .....................................................11 (b) High Power Consumption.....................................................12 (c) Machine Unavailability ..........................................................12 (d) Delayed Shipments ..............................................................13 (e) Accumulation of Unfinished Goods ......................................13 (f) Unnecessary Maintenance....................................................14 (g) Quality Problems ..................................................................14 (h) Bad Company Image............................................................15 (i) Occupational Hazards ...........................................................15 Summary ................................................................................ 16 Section 2: How is Machine Vibration Described? ... 17 How is Vibration Described?.................................................. 18 What is Amplitude? ................................................................ 19 What is Frequency? ............................................................... 22 What is A Waveform?............................................................. 23 What is A Spectrum?................