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AN INTRODUCTION TO
PREDICTIVE MAINTENANCE
Second Edition
AN INTRODUCTION
TO PREDICTIVE
MAINTENANCE
Second Edition
R. Keith Mobley
Amsterdam London New York Oxford Paris Tokyo
Boston San Diego San Francisco Singapore Sydney
Butterworth-Heinemann is an imprint of Elsevier Science.
Copyright © 2002, Elsevier Science (USA). All rights reserved.
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Library of Congress Cataloging-in-Publication Data
Mobley, R. Keith, 1943–.
An introduction to predictive maintenance / R. Keith Mobley.—2nd ed.
p. cm.
Includes index.
ISBN 0-7506-7531-4 (alk. paper)
1. Plant maintenance—Management. I. Title.
TS192 .M624 2002
658.2¢02—dc21
2001056670
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1 Impact of Maintenance 1
1.1 Maintenance management methods 2
1.2 Optimizing predictive maintenance 10
2 Financial Implications and Cost
Justification 23
2.1 Assessing the need for condition
monitoring 24
2.2 Cost justification 25
2.3 Justifying predictive maintenance 29
2.4 Economics of preventive maintenance 32
3 Role of Maintenance Organization 43
3.1 Maintenance mission 43
3.2 Evaluation of the maintenance
organization 44
3.3 Designing a predictive maintenance
program 50
4 Benefits of Predictive Maintenance 60
4.1 Primary uses of predictive
maintenance 61
5 Machine-Train Monitoring
Parameters 74
5.1 Drivers 75
5.2 Intermediate drives 78
5.3 Driven components 86
6 Predictive Maintenance Techniques 99
6.1 Vibration monitoring 99
6.2 Themography 105
6.3 Tribology 108
6.4 Visual inspections 111
6.5 Ultrasonics 111
6.6 Other techniques 112
7 Vibration Monitoring and Analysis 114
7.1 Vibration analysis applications 114
7.2 Vibration analysis overview 117
7.3 Vibration sources 122
7.4 Vibration theory 125
7.5 Machine dynamics 132
7.6 Vibration data types and formats 146
7.7 Data acquisition 152
7.8 Vibration analyses techniques 161
Appendix 7.1 Abbreviations 165
Appendix 7.2 Glossary 166
Appendix 7.3 References 171
8 Thermography 172
8.1 Infrared basics 172
8.2 Types of infrared instruments 174
8.3 Training 175
8.4 Basic infrared theory 176
8.5 Infrared equipment 178
8.6 Infrared thermography safety 179
8.7 Infrared thermography procedures 179
8.8 Types of infrared problems 179
Appendix 8.1 Abbreviations 183
Appendix 8.2 Glossary 183
Appendix 8.3 Electrical terminology 187
Appendix 8.4 Materials list 193
9 Tribology 202
9.1 Lubricating oil analysis 203
9.2 Setting up an effective program 208
10 Process Parameters 217
10.1 Pumps 218
10.2 Fans, blowers, and fluidizers 225
10.3 Conveyors 229
10.4 Compressors 229
10.5 Mixers and agitators 240
10.6 Dust collectors 240
10.7 Process rolls 241
10.8 Gearboxes/reducers 242
10.9 Steam traps 249
10.10 Inverters 249
10.11 Control valves 249
10.12 Seals and packing 251
11 Ultrasonics 256
11.1 Ultrasonic applications 256
11.2 Types of ultrasonic systems 257
11.3 Limitations 258
12 Visual Inspection 259
12.1 Visual inspection methods 260
12.2 Thresholds 263
13 Operating Dynamics Analysis 267
13.1 It’s not predictive maintenance 267
14 Failure-Mode Analysis 285
14.1 Common general failure modes 286
14.2 Failure modes by machine-train
component 301
15 Establishing A Predictive
Maintenance Program 325
15.1 Goals, objectives, and benefits 325
15.2 Functional requirements 326
15.3 Selling predictive maintenance
programs 330
15.4 Selecting a predictive maintenance
system 334
15.5 Database development 343
15.6 Getting started 348
16 A Total-Plant Predictive
Maintenance Program 352
16.1 The optimum predictive maintenance
program 353
16.2 Predictive is not enough 356
17 Maintaining the Program 389
17.1 Trending techniques 389
17.2 Analysis techniques 390
17.4 Additional training 392
17.5 Technical support 393
17.6 Contract predictive maintenance
programs 393
18 World-Class Maintenance 394
18.1 What is world-class maintenance? 394
18.2 Five fundamentals of world-class
performance 395
18.3 Competitive advantage 396
18.4 Focus on quality 397
18.5 Focus on maintenance 398
18.6 Overall equimpment effectiveness 402
18.7 Elements of effective maintenance 406
18.8 Responsibilities 412
18.9 Three types of maintenance 413
18.10 Supervision 419
18.11 Standard procedures 424
18.12 Workforce development 426
Index 435
Maintenance costs are a major part of the total operating costs of all manufacturing
or production plants. Depending on the specific industry, maintenance costs can rep-
resent between 15 and 60 percent of the cost of goods produced. For example, in food-
related industries, average maintenance costs represent about 15 percent of the cost
of goods produced, whereas maintenance costs for iron and steel, pulp and paper, and
other heavy industries represent up to 60 percent of the total production costs.
These percentages may be misleading. In most American plants, reported maintenance
costs include many nonmaintenance-related expenditures. For example, many plants
include modifications to existing capital systems that are driven by market-related
factors, such as new products. These expenses are not truly maintenance and should
be allocated to nonmaintenance cost centers; however, true maintenance costs are
substantial and do represent a short-term improvement that can directly impact plant
profitability.
Recent surveys of maintenance management effectiveness indicate that one-third—33
cents out of every dollar—of all maintenance costs is wasted as the result of unnec-
essary or improperly carried out maintenance. When you consider that U.S. industry
spends more than $200 billion each year on maintenance of plant equipment and facil-
ities, the impact on productivity and profit that is represented by the maintenance oper-
ation becomes clear.
The result of ineffective maintenance management represents a loss of more than
$60 billion each year. Perhaps more important is the fact that ineffective maintenance
management significantly affects the ability to manufacture quality products that
are competitive in the world market. The losses of production time and product
quality that result from poor or inadequate maintenance management have had a
dramatic impact on U.S. industries’ ability to compete with Japan and other countries
1
IMPACT OF MAINTENANCE
1
[...]...2 An Introduction to Predictive Maintenance that have implemented more advanced manufacturing and maintenance management philosophies The dominant reason for this ineffective management is the lack of factual data to quantify the actual need for repair or maintenance of plant machinery, equipment, and systems Maintenance scheduling has been, and in many instances still is, predicated... Improving maintenance efficiency and effectiveness In most TPM plans, though, the operator is directly involved in some level of maintenance This effort involves better planning and scheduling better preventive maintenance, predictive maintenance, reliability-centered maintenance, spare parts equipment stores, and tool locations—the collective domain of the maintenance department and the maintenance technologies... catastrophic failures and the need for corrective maintenance These methods will also extend the useful life and minimize the life cycle cost of critical production systems 16 An Introduction to Predictive Maintenance Predictive Maintenance Is More Than Maintenance Traditionally, predictive maintenance is used solely as a maintenance management tool In most cases, this use is limited to preventing unscheduled... maintenance (TPM) and reliability-centered maintenance (RCM), have been developed and touted as the panacea for ineffective maintenance Many domestic plants have partially adopted one of these quick-fix methods in an attempt to compensate for perceived maintenance shortcomings Total Productive Maintenance Touted as the Japanese approach to effective maintenance management, the TPM concept was developed... production plants 1.1 MAINTENANCE MANAGEMENT METHODS To understand a predictive maintenance management program, traditional management techniques should first be considered Industrial and process plants typically employ two types of maintenance management: run -to- failure or preventive maintenance 1.1.1 Run -to- Failure Management The logic of run -to- failure management is simple and straightforward: When... cost of maintenance It also improves the product quality, productivity, and profitability of manufacturing and production plants Predictive maintenance is a condition-driven preventive maintenance program Instead of relying on industrial or in-plant average-life statistics (i.e., mean-time -to- failure) to schedule maintenance activities, predictive maintenance uses direct monitoring of the mechanical... unscheduled downtime and/or catastrophic failures Although this function is important, predictive maintenance can provide substantially more benefits by expanding the scope or mission of the program As a maintenance management tool, predictive maintenance can and should be used as a maintenance optimization tool The program’s focus should be on eliminating unnecessary downtime, both scheduled and unscheduled;... preventive maintenance downtime, or delays Maintenance prevention, not quick-fixes of breakdowns, should be the objective Maintenance planning and scheduling are essential parts of effective maintenance Planners must develop and implement both preventive and corrective maintenance tasks that achieve maximum use of maintenance resources and the production capacity of plant systems Good planning is not an option... means to 22 An Introduction to Predictive Maintenance effectively communicate and coordinate the integrated functions, such as sales, production, maintenance, and procurement, into an effective unit Large plants must also exercise caution The tendency is to become excessive when implementing continuous improvement programs Features are added to the information management system, predictive maintenance. .. their interest to try, however, because without financial data there can be no satisfactory cost justification for CM, and hence no will or investment to improve the maintenance situation Ultimately, their department and the company will be the losers if poor maintenance leads to an uncompetitive marketplace position Some of the factors relevant to maintenance engineering that can have an adverse effect . AN INTRODUCTION TO
PREDICTIVE MAINTENANCE
Second Edition
AN INTRODUCTION
TO PREDICTIVE
MAINTENANCE
Second Edition
R. Keith Mobley
Amsterdam. of manufacturing and pro-
duction plants.
1.1 MAINTENANCE MANAGEMENT METHODS
To understand a predictive maintenance management program, traditional manage-
ment
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