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MAINTENANCE ENGINEERING

(B.E./B.Tech. Mechanical Engineering Students)

As per Anna University

New Revised Syllabus

Dr. S. RAMACHANDRAN, M.E., Ph.D.,

Professor – Mech.

Sathyabama Institute of Science and Technology,

Chennai – 600 119.

Dr. M. SARAVANAN, M.E., Ph.D.,

Principal

SSM Institute of Engineering & Technology

Dindigul.

AIRWALK PUBLICATIONS

(Near All India Radio)

80, Karneeshwarar Koil Street,

Mylapore, Chennai – 600 004.

Ph.: 2466 1909, 94440 81904

Email: [email protected], [email protected]

www.airwalkbooks.com, www.srbooks.org

© First Edition: June 2018

This book or part thereof should not be reproduced in any form without the

written permission of the publisher.

Price: Rs. 150/-

ISBN: 978-93-88084-06-2

Typesetting by: Akshayaa DTP, 48E, Sri Gangaiya Avenue, 2nd

Cross Street, Ramapuram, Chennai – 89, Mobile: 9551908934.

Printed at:

ANNA UNIVERSITY SYLLABUS − R13

ME6012 − MAINTENANCE ENGINEERING

UNIT I: PRINCIPLES AND PRACTICES OF MAINTENANCE PLANNING

Basic Principles of maintenance planning − Objectives and principles

of planned maintenance activity − Importance and benefits of sound

Maintenance systems − Reliability and machine availability − MTBF,

MTTR and MWT − Factors of availability − Maintenance organization

− Maintenance economics.

UNIT II: MAINTENANCE POLICIES − PREVENTIVE MAINTENANCE

Maintenance categories − Comparative merits of each category −

Preventive maintenance, maintenance schedules, repair cycle −

Principles and methods of lubrication − TPM.

UNIT III: CONDITION MONITORING

Condition Monitoring − Cost comparison with and without CM −

On-load testing and offload testing − Methods and instruments for CM

− Temperature sensitive tapes − Pistol thermometers − wear-debris

analysis

UNIT IV: REPAIR METHODS FOR BASIC MACHINE ELEMENTS

Repair methods for beds, slide ways, spindles, gears, lead screws and

bearings − Failure analysis − Failures and their development − Logical

fault location methods − Sequential fault location.

UNIT V: REPAIR METHODS FOR MATERIAL HANDLING EQUIPMENT

Repair methods for Material handling equipment − Equipment records

− Job order systems − Use of computers in maintenance.

*********

ACKNOWLEDGEMENT

It has been a long time dream to write this book for the young

budding Mechanical Engineers, which came true. Keeping in mind, the

importance of fundamentals of the subject, and as well as an approach

towards the examination point of view, this book has been written and

compiled with easily understandable format. Simple drawings have been

drawn and many important problems have been solved which are

frequently asked in various University Examinations. Crisp and precise

explanations are rendered for the problems and as well as the theory

associated with it. This book is an eye opener for the beginner with

no prior knowledge on this subject. It is quite relevant to state here

that our parents’ blessings gave us the required courage to write this

book.

We express our sincere gratitude to the honourable Chairman

Thiru Dr. B. BABU MANOHARAN, M.A., M.B.A., Ph.D., Chairman

and Managing Director, St. Joseph’s Group of Institutions, who is the

GOD FATHER for us, who has given strong support and

encouragement to write many number of books and thanks to beloved

Directors Mr. B. SHASHI SEKAR, M.Sc., B. JESSIE PRIYA, M.Com.,

St. Joseph’s Group of Institutions, for their constant encouragement and

support to bring out this book a success one.

Any errors, omissions and suggestions for the improvement of this

book, brought to our notice will be thankfully acknowledged and

incorporated in the next edition.

AUTHORS

CONTENTS

UNIT – I

PRINCIPLES AND PRACTICES OF

MAINTENANCE PLANNING

1.1. – 1.58

1.1. Introduction to maintenance 1.2

1.2. Basic concepts of maintenance 1.2

1.3. Purpose of maintenance 1.3

1.4. Functions of maintenance 1.4

1.4.1. Basic Functions 1.4

1.4.2. Composite Functions 1.7

1.5. Objectives of maintenance 1.8

1.6. Principles of maintenance 1.9

1.7. Benefits of maintenance 1.12

1.8. Effects of maintenance 1.12

1.9. Maintenance planning 1.14

1.9.1. Basic principles of maintenance planning 1.14

1.9.2. Steps of job planning 1.15

1.9.3. Planning techniques 1.15

1.9.4. Planning objectives 1.16

1.10. Basic levels of planning process (Depending on the planning

Horizon)

1.17

1.10.1. Long range planning 1.17

1.10.2. Medium-range planning 1.18

Contents i

1.11. Objectives and principles of planned maintenance activity 1.18

1.12. Sound maintenance system 1.19

1.12.1. Importance and benefits of Sound Maintenance

systems

1.20

1.13. Quality in maintenance 1.21

1.14. Reliability 1.21

1.15. Difference between reliability and quality 1.22

1.16. Bathtub curve 1.23

1.17. Failure rate (λ) 1.24

1.17.1. Failure pattern of equipment 1.24

1.17.2. Mean Time Between Failure (MTBF) 1.25

1.17.3. Mean Time To Failure (MTTF) 1.26

1.17.4. Mean Time To Repair (MTTR) 1.28

1.18. System reliability model 1.28

1.18.1. Series systems 1.29

1.18.2. Parallel reliability 1.31

1.18.3. Combination of series and parallel 1.32

1.19. Maintainability 1.33

1.20. Availability 1.34

1.20.1. Inherent availability 1.35

1.20.2. Achieved availability 1.36

1.20.3. Operational availability 1.36

1.21. Reliability, Availability and Maintainability (RAM) 1.37

ii Contents

1.22. Maintenance organization 1.38

1.22.1. Objectives of maintenance organization 1.41

1.22.2. Types of maintenance organization 1.42

1.22.3. Line and staff organization 1.42

1.22.3.1. Advantages of line and staff organization 1.45

1.22.3.2. Disadvantages of line and staff

organization

1.46

1.22.4. Functional organization 1.47

1.22.4.1. Advantages of functional organization 1.48

1.22.4.2. Disadvantages of functional organization 1.49

1.22.5. Centralized and decentralized maintenance organization 1.50

1.22.5.1. Advantages of centralized maintenance

organization

1.51

1.22.5.2. Disadvantages of centralized maintenance

organization

1.51

1.22.5.3. Advantages of decentralized maintenance

organization

1.52

1.22.5.4. Disadvantages of decentralized

maintenance organization

1.52

1.22.5.5. Advantages of partially decentralized

organization

1.53

1.22.5.6. Disadvantages of partially decentralized

organization

1.54

1.23. Maintenance economics 1.54

1.23.1. Maintenance budgeting 1.57

1.23.2. Types of maintenance budgeting 1.57

Contents iii

1.23.3. Preparation of maintenance budget 1.57

1.23.4. Advantages of maintenance budgeting 1.58

UNIT – II

MAINTENANCE POLICIES –

PREVENTIVE MAINTENANCE

2.1 – 2.70

2.1. Maintenance strategies/categories 2.2

2.2. Basic for selection 2.2

2.3. Breakdown maintenance 2.5

2.3.1. Advantages of breakdown maintenance 2.7

2.3.2. Disadvantages of breakdown maintenance 2.7

2.4. Corrective maintenance 2.7

2.4.1. Advantages of corrective maintenance 2.8

2.5. Preventive maintenance 2.9

2.5.1. Process flow of Preventive Maintenance (PM) 2.10

2.5.2. Frequency in preventive maintenance 2.11

2.5.3. Advantages of preventive maintenance 2.12

2.5.4. Disadvantages of preventive maintenance 2.13

2.6. Predictive Maintenance (PdM) 2.13

2.6.1. Components of a predictive maintenance

programme

2.15

2.6.2. Advantages of predictive maintenance 2.16

2.6.3. Disadvantages of predictive maintenance 2.16

2.7. Condition Based Maintenance System (CBMS) 2.16

2.7.1. Methodology of condition based maintenance 2.17

iv Contents

2.8. Reliability Centered Maintenance (RCM) 2.20

2.8.1. Steps of RCM 2.22

2.8.2. RCM flow diagram 2.26

2.8.3. Advantages of RCM process 2.27

2.8.4. Disadvantages of RCM process 2.27

2.9. Total Productive Maintenance (TPM) 2.27

2.9.1. Features of TPM 2.28

2.9.2. Methodology of TPM 2.29

2.9.3. Benefits of TPM 2.32

2.10. Six sigma maintenance 2.33

2.10.1. Six sigma maintenance process 2.35

2.11. Lean maintenance 2.37

2.11.1. Challenges of lean maintenance 2.38

2.11.2. Lean maintenance process 2.39

2.12. 5-Zero maintenance concept 2.39

2.13. 5-S concept in maintenance 2.42

2.14. Business Centred Maintenance (BCM) 2.46

2.14.1. Six pillars of BCM 2.47

2.15. Quality assured maintenance 2.48

2.16. Maintenance scheduling 2.49

2.16.1. Scheduling principles 2.49

2.16.2. Stakeholders and their role 2.51

2.16.3. Schedule types and techniques 2.53

2.16.4. Project scheduling 2.55

Contents v

2.17. Repair 2.59

2.17.1. Repair cycle 2.60

2.18. Lubrication 2.61

2.18.1. Methods of lubrication 2.64

2.19. TPM and TQM 2.68

UNIT – III

CONDITION MONITORING3.1. – 3.116

3.1. Condition Monitoring (CM) 3.2

3.1.1 Basic concept of condition monitoring 3.4

3.1.2. Key features of condition monitoring 3.5

3.1.3. Types of condition monitoring 3.6

3.2. Performance monitoring 3.8

3.3. Methods and instruments for condition monitoring 3.9

3.4. Types of condition monitoring systems 3.13

3.5. Visual, tactical and aural monitoring 3.17

3.6. Leakage monitoring 3.19

3.7. Temperature monitoring 3.22

3.7.1. Thermistors 3.24

3.7.2. Pistol thermometer 3.27

3.8. Temperature sensitive tapes 3.29

3.9. Thermography 3.31

3.9.1. Active thermography 3.31

vi Contents

3.9.2. Passive thermography 3.33

3.9.3. Applications of thermography 3.33

3.9.4. Advantages of thermography 3.34

3.10. Thickness monitoring 3.34

3.11. Vibration monitoring 3.36

3.11.1. Vibration fundamental 3.39

3.11.2. Vibration analysis 3.40

3.12. Vibration transducers 3.41

3.12.1. Accelerometer 3.42

3.12.2. Velocity transducer 3.43

3.12.3. Lead Zirconate Titanate (PZT) actuators 3.44

3.12.4. Fast Fourier Transform (FFT) Analyzer 3.44

3.12.5. Vibration shakers 3.46

3.12.6. Vibration holograph 3.46

3.13. Machinery vibration trouble shooting 3.47

3.13.1. Vibration isolation 3.49

3.13.2. Causes of vibration 3.50

3.14. Machinery vibration standard, severity chart and acceptable

limits

3.52

3.14.1. Vibration severity chart 3.54

3.15. Lubricant monitoring 3.55

3.15.1. Components and techniques of lubricant monitoring 3.59

3.15.2. Filter debris analysis & filtergrams 3.60

Contents vii

3.16. Wear Debris Analysis (WDA) 3.62

3.16.1. Wear debris analysis methods 3.65

3.17. Ferrography 3.68

3.17.1. Benefit of ferrography 3.70

3.18. Spectroscopic Oil Analysis Program (SOAP) 3.70

3.19. Crack monitoring 3.71

3.9.1. Liquid penetrant testing 3.74

3.19.1.1. Principle 3.75

3.19.1.2. Penetrants 3.77

3.19.1.3. Developer 3.77

3.19.1.4. Procedure for Liquid Penetrant Inspection

(LPI)

3.78

3.19.1.5. Advantages and limitations of LPI 3.84

3.19.1.6. Limitations 3.85

3.19.1.7. Applications 3.85

3.19.2. Magnetic particle testing 3.87

3.19.2.1. Principles of MPI 3.88

3.19.2.2. Advantages of MPI 3.89

3.19.2.3. Limitations of MPI 3.90

3.19.3. Ultrasonic testing 3.91

3.19.3.1. Ultrasonic waves 3.91

3.19.3.2. Principle 3.92

3.19.3.3. Modes of wave propagation 3.94

viii Contents

3.19.3.4. Ultrasonic testing techniques 3.94

3.19.3.5. Advantages of ultrasonic inspection 3.98

3.19.3.6. Limitations of ultrasonic testing 3.99

3.19.3.7. Applications of ultrasonic testing 3.100

3.19.4. Radiography testing 3.101

3.19.4.1. Principle 3.101

3.19.4.2. Advantages of radiography testing 3.103

3.19.4.3. Disadvantages of radiography testing 3.104

3.19.4.4. Applications of radiography testing 3.104

3.19.5. Eddy current testing 3.105

3.19.5.1. Principle of eddy current testing 3.106

3.19.5.2. Advantages of eddy current testing 3.108

3.19.5.3. Disadvantages of eddy current testing 3.108

3.20. Corrosion monitoring 3.109

3.21. Cost comparision with and without condition monitoring 3.110

3.22. Load testing 3.114

UNIT – IV

REPAIR METHODS FOR BASIC MACHINE

ELEMENTS

4.1. – 4.42

4.1. Repair methods for slide ways 4.2

4.2. Repair method of beds 4.4

4.3. Repair methods for spindles 4.5

Contents ix

4.4. Repair methods for gears 4.7

4.4.1. Surface fatigue 4.8

4.4.2. Heavy wear 4.9

4.4.3. Scoring 4.9

4.4.4. Plastic flow 4.10

4.5. Repair methods of bearings 4.11

4.6. Defect and failure 4.19

4.7. Basics of failure 4.21

4.8. Failure and their development 4.23

4.9. Failure analysis 4.25

4.10. Local fault location method 4.27

4.10.1. Fault Tree Analysis (FTA) 4.28

4.10.2. Event Tree Analysis (ETA) 4.30

4.11. Root Cause Analysis (RCA) 4.31

4.12. Root Cause Failure Analysis (RCFA) 4.34

4.13. Difference between RCA and RCFA 4.34

4.14. Failure Modes and Effects Analysis (FMEA) 4.35

4.14.1. Benefits of FMEA 4.40

4.15. Failure Modes Effect Criticality Analysis (FMECA) 4.40

x Contents

UNIT – V

REPAIR METHODS FOR MATERIAL

HANDLING EQUIPMENTS

5.1. – 5.28

5.1. Material Handling Equipment (MHE) 5.2

5.2. Requirement of MHE maintenance 5.2

5.3. Principles of material handling 5.3

5.4. Major categories of MHE 5.5

5.5. Conveyors 5.6

5.5.1. Maintenance strategies for conveyors 5.6

5.5.2. Stages of preventive maintenance for conveyors 5.7

5.6. Cranes 5.7

5.6.1. Maintenance strategies for cranes 5.8

5.6.2. Stages of preventive maintenance for cranes 5.9

5.7. Industrial trucks 5.9

5.8. Selection of material handling equipments 5.10

5.9. Equipment records 5.11

5.9.1. Advantages of equipment records 5.13

5.10. Job order systems 5.14

5.10.1. Structure of maintenance job order 5.14

5.10.2. Job permit system 5.15

Contents xi

5.10.3. Planning and scheduling of job order 5.17

5.10.4. Job cards and job card procedures 5.18

5.11. Computer-aided Maintenance Management System (CMMS) 5.19

5.11.1. Functions of CMMS 5.20

5.11.2. Factors affecting selection of CMMS 5.22

5.11.3. Advantages of CMMS 5.23

5.12. Maintenance integration 5.23

5.12.1. Various steps in maintenance integration 5.24

5.12.1.1. Aligning of the Engineering and

Maintenance Functions under Production

Umbrella

5.25

5.12.1.2. Involvement of Maintenance Staff Early

in the Concept and Design Phase itself

5.25

5.12.1.3. Awareness to production/machine

specification

5.26

5.12.1.4. Third party consultancy assistance 5.26

5.12.1.5. Integration of e-business software with

enterprise resource planning packages like

SAP

5.26

Short Questions and Answers Q.P.1 – Q.P.39

Index I.1 – I.3

xii Contents

UNIT – I

PRINCIPLES

AND PRACTICES OF

MAINTENANCE PLANNING

* Basic Principles of maintenance planning.

* Objectives and principles of planned maintenance

activity.

* Importance and benefits of sound Maintenance

systems.

* Reliability and machine availability.

* MTBF, MTTR and MWT.

* Factors of availability.

* Maintenance organization − Maintenance economics.

1.1. INTRODUCTION TO MAINTENANCE

H Maintenance Engineering is a branch of engineering,

where engineering concepts are applied for the

optimization of equipment, procedures and departmental

budgets to achieve better reliability, maintainability and

availability of equipment.

H Due to rising amount of equipment, system, machineries

and infrastructure, the importance of maintenance and

hence maintenance engineering is also increasing

day-by-day.

H Maintenance is a process, in which working condition of

plant or machinery is maintained at the optimum level as

to give maximum output. Maintenance is done through

repair, partial replacement and total replacement.

1.2. BASIC CONCEPTS OF MAINTENANCE

H The concept of maintenance is derived from the concept

of operations (CONOPS), which describes briefly about

the maintenance consideration, constraints and plans for

operational support of the system or equipment under

development.

1.2 Maintenance Engineering - www.airwalkbooks.com

H When the system design activities are performed, the

maintenance concept continues to shape system design

decisions and detailed maintenance and product support

requirement.

1.3. PURPOSE OF MAINTENANCE

H The main purpose of regular maintenance in an industrial

perspective is to ensure that all equipment required for

production is operating at maximum efficiency at all times.

H By regular inspections, cleaning, lubricating and making

minor adjustments, minor problems can be detected and

corrected before they become a major problem which may

lead to shut down a production line.

H As compared to the cost of major breakdown, the cost of

regular maintenance is very small.

H A maintenance program for a particular industry to

succeed, it requires company-wide participation and

support by everyone ranging from the top executive to the

shop floor personnel.

Principles and Practices of Maintenance Planning 1.3

1.4. FUNCTIONS OF MAINTENANCE

H To obtain cost effective, smooth and reliable maintenance

in a company various functions has to be coordinated.

H In recent days, the objective of maintenance functions are

being considered as Maintenance affects all aspects of

business effectiveness and risk − safety, environmental

integrity, energy efficiency, product quality and customer

service as well.

H Like earlier days, it is not only considered to optimize

plant availability and cost.

The functions of maintenance can be grouped into two

categories and they are:

(a) Basic functions and

(b) Composite functions.

1.4.1. Basic Functions

The basic types of maintenance functions are as follows,

1. Replace: An unserviceable item is removed and in its place,

a serviceable counter part is installed. This is called replacement.


2. Repair: Something which is damaged, faulty or worn is

restored to a good condition.

3. Overhaul: In order to examine, a piece of machinery or

equipment is taken apart and if necessary, it will be repaired.

4. Rebuild: These are the services or actions that are necessary

for the restoration of unserviceable equipment to a like new

condition in accordance with original manufacturing standards.

5. Service/Lubricate: Several periodic operations are required to

keep an item in proper operating conditions. Some of the services

are cleaning, preserving, draining, painting, lubricating etc.

6. Inspect/Check: By comparing a machine’s physical,

mechanical and electrical characteristics with established standards

through examination, the serviceability of the machine can be

determined.

7. Testing: To see the performance of a machine whether it is

working efficiently or not, several testings are done after a period

of time.


8. Adjust: To maintain a machine within its prescribed limits,

some adjustments are done by bringing the machine into proper

or exact position or by setting the operating characteristics to

specified parameters.

9. Align: The specified variable elements are adjusted in a

machine to bring about optimum and desired performance.

10. Calibrate: Correcting the instrument with a standard scale of

reading is called calibration.

11. Measure: This is the process of ascertaining the extent,

dimensions or quantity of something, such as measurement of

flow or heat or pressure etc. with suitable instrument.

12.Winding: It is a symmetrically laid, electrically conducting

current path in any device such as electric motor.

13. Install: A machine or its parts are fixed or placed in such

a manner that it allows proper functioning of an equipment or

system.


1.4.2. Composite Functions

Maintenance engineers are often required to have knowledge

of many types of equipment and machinery for which they are

responsible. Some of their composition functions are as follows,

1. To protect the buildings, structures and plants/factories.

2. To increase equipment ability and to reduce down times.

3. To analyze repetitive failure and to arrange their

elimination.

4. To forecast maintenance spares, tools and consumables

and to help their procurement and inventory management.

5. To control and direct labour forces.

6. To maximize the utilization of available resources.

7. To ensure safety of installation and to reduce

environmental pollution.

8. To minimize the production cost.

9. To prepare maintenance budgets.

10. Waste recovery & waste reduction.

11. To improve technical communication.

12. To train maintenance personnel on related jobs.


1.5. OBJECTIVES OF MAINTENANCE

The objectives of maintenance are as follows,

1. Maintenance helps in implementation of suitable

procedures for procurement, storage and consumption of

spares, tools and consumables etc.

2. By minimizing the rate of deterioration, investments can

be reduced.

3. Maintenance helps management to take decisions on

replacements or new investments and actively participate

in specification preparation, equipment selection etc.

4. Maintenance helps to maintain plants and equipments at

its maximum operating efficiency, to reduce downtime

and ensure operational safety.

5. Maintenance helps to meet the availability requirements

for critical equipments.

6. Maintenance helps to increase the profit of production

system.


1.6. PRINCIPLES OF MAINTENANCE

In a system, to guide the employees to work efficiently and

effectively in order to achieve overall objectives of the

maintenance system, several principles are followed. These are

called principles of maintenance.

The main principles of maintenance are as follows

1. Plant Management in Maintenance work

The maintenance function plays an important role to provide

safe and effective operation of the equipment to achieve the

desired production targets on time economically.

2. Maintenance Objectives Vs Plant Production

In order to reduce the number of breakdowns during the

operating life cycle of the equipment, the programme of

scheduled maintenance must be followed regularly.

3. Establishment of work-order and recording system

It is necessary to maintain proper records or entries to

monitor the health of the equipment as well as its life span at

every workstation. In recent days, in many organizations, this

work is being performed with the help of computers.


4. Information Based Decision Making

By using reliable information system, the maintenance

objectives can be successfully achieved. This information systems

may be used for decision making in respect of manpower and

spare parts requirements.

5. Adherence to Planned Maintenance Systems

Several instruction must be given to the employees before

operating a machine. Otherwise, this often gives rise to

unscheduled breakdowns of equipment. If manufacturer’s

instructions are given properly, it will not only enhance the life

of equipment but also ensure proper use of manpower.

6. Planning of Maintenance Functions

For effective utilization of manpower and resources, and to

avoid incurring of heavy shutdown costs due to equipment

breakdowns, all kinds of jobs must be planned in advance.

7. Manpower for Maintenance

The maintenance functions involved in all jobs must be

carefully examined, and motion study for the calculation of

manpower requirement should be done.


8. Work Force Control

Since the nature of maintenance work is quite unpredictable,

the cost of maintenance function can be kept under control only

with proper monitoring of the work force. Due to this reason,

sufficient field data are required to be collected regularly,

accurately and completely.

9. Quality & Availability of Spare Parts

At the time of purchase of an equipment, some spare parts

are also supplied by the manufacturers, which may not be

sufficient for all types of faults encountered in practice and for

the whole life of the equipment. Thus, it is necessary to stock a

complete range and scale of genuine spare parts to sustain the

functionalities of the equipment without endangering safety.

10. Training of the Maintenance Workforce

Whenever a new equipment is purchased, the maintenance

personnel and the operating personnel must be trained properly.

Now-a-days, training of new recruits under skilled workers and

supervisors is practiced in many industries.


1.7. BENEFITS OF MAINTENANCE

Benefits of Maintenance are as follows

1. Better process stability.

2. Reduced maintenance cost and reduced life cycle cost.

3. Reduced maintenance part inventory.

4. Reduced risk of environmental issues.

5. Reduced overtime and reduced out-sourcing.

6. Lower production unit cost.

7. Extended equipment life and lesser asset replacement.

8. Reduced non-conformance reports and warranty claims,

and reduced lapses in statutory obligations.

9. Improved sense of employee pride/ownership.

10. Improved employee safety and improved housekeeping.

1.8. EFFECTS OF MAINTENANCE

H Maintenance plays an important role in any production

system.

H For a particular environment, if the right kind of

maintenance function is not selected, it may lead to the


serious problem of either over maintenance or under

maintenance.

H Cost effective maintenance helps to boost the productivity

in a production system.

H It is very important for the maintenance team to know

how much work to maintain.

H The lifetime of an equipment depends on the nature of

maintenance function.

H If the equipment is maintained properly, the lifetime of

the equipment will increase, and on the other hand,

carelessness in maintenance would lead to an early failure

of the equipment.

H When a equipment is in good working condition, the

operator should feel comfortable to use it, otherwise there

is a tendency to let the equipment deteriorate further.

H To obtain desired output in a maintenance operation, there

should be selective development of skilled, semi-skilled

and unskilled labour and proper division of responsibilities

among them in order to make full use of the skilled

workforce available.


1.9. MAINTENANCE PLANNING

1.9.1. Basic Principles of Maintenance Planning

H Basically planning of maintenance deals with answering

two questions, “what” jobs are to be done and “how”

those jobs are to be done.

H While answering these two questions, some supplementary

questions such as “Why the job is to be done” and

“where the job is to be done” are also to be answered,

which ultimately help in developing “what” and “how” of

the job.

H Effective planning and scheduling contribute significantly

to the following:

(i) Reduced maintenance cost.

(ii) Improved utilization of the maintenance workforce by

reducing delays and interruptions.

(iii) Improved quality of maintenance work by adopting

the best methods and procedures and assigning the

most qualified workers for the job.


1.9.2. Steps of Job Planning

For proper job planning, some steps are to be followed and

they are:

(a) Knowledge Base: I t includes knowledge about

equipment, job, available techniques, materials and

facilities etc.

(b) Job Investigation at Site: It gives a clear preparation of

the total job and also helps in ascertaining certain

objectives.

(c) To identify and documentation of the work.

(d) To develop repair plan.

(e) Preparation of tools, tackles and facilities list.

(f) To estimate the time required to do the job.

(g) Work-order feedback forms / plan.

1.9.3. Planning Techniques

H There are several techniques of planning which a planner

may use to plan and putdown that on paper or computer

etc. Some of these techniques are as follows,


(i) Work breakdown structure: It involves breaking the

total job down into lower levels of tasks.

(ii) Work measurement: It involves careful analysis of a

task, its size, the method used in its performance and its

efficiency.

(iii) Work Packages: It involves details of what work is

required and when it is to be delivered, negotiation to

agree for the work with the line manager and for essential

clearances, arrangement of the broken down works in

some logical sequence, determination of works which can

be done in parallel and putting them on paper or

computer etc.

1.9.4. Planning Objectives

H Minimizing the idle time of maintenance workers.

H Maximizing the efficient use of work time, material, and

equipment.

H Maintaining the operating equipment at a responsive level

to the need of production in terms of delivery schedule

and quality.


1.10. BASIC LEVELS OF PLANNING PROCESS (Depending on the

Planning Horizon)

1. Long-rang planning: It covers a period of 3 to 5 years

and sets plans for future activities and long-range

improvement.

2. Medium-range planning: It covers a period of 1 month

to 1 year.

3. Short-rang planning: It covers a period of 1 day to 1

week. It focuses on the determination of all the elements

required to perform maintenance tasks in advance.

1.10.1. Long Range Planning

Needs to utilize the following:

1. Sound forecasting techniques to estimate the maintenance

load.

2. Reliable job standards times to estimate staffing

requirements.

3. Aggregate planning tools such as linear programming to

determine resource requirements, sets plans for future

activities and long-range improvement.


1.10.2. Medium-Range Planning

H Specify how the maintenance workers will operate.

H Provide details of major overhauls, construction jobs,

preventive maintenance plans, and plant shut downs.

H Balances the need for staffing over the period covered.

H Estimates the required spare parts and material acquisition.

1.10.3. Short-Range Planning

H It focuses on the determination of all the elements required

to perform maintenance tasks in advance.

1.11. OBJECTIVES AND PRINCIPLES OF PLANNED

MAINTENANCE ACTIVITY

H Analysis of repetitive equipment failures.

H Estimation of maintenance costs and evaluation of

alternatives.

H Forecasting of spare parts.

H Assessing the needs for equipment replacements and

establish replacement programs when due application of


scheduling and project management principles to

replacement programs.

H Assessing required maintenance tools and skills required

for efficient maintenance of equipment.

H Assessing required skills required for maintenance

personnel.

H Reviewing personnel transfers to and from maintenance

organizations assessing and reporting safety hazards

associated with maintenance of equipment.

1.12. SOUND MAINTENANCE SYSTEM

H Human ear can detect frequencies between 20 Hz and

20 kHz. This range of frequency is called audible range

or sonic range.

H Frequencies above this range are referred to as ultrasonic

or ultrasound.

H Controlling of noise pollution is very important as noise

affects human being in both ways, physically and

psychologically and prolonged exposure to high noise

level can lead to permanent hearing loss.


H Several techniques are used to identify the noise sources.

Some of these are as follows:

P Acoustic ducts.

P Surface intensity approach.

P Acoustic intensity approach and sound-pressure

monitoring.

P Subjective assessment.

P Impulsive noise monitoring.

P Infrasonic noise monitoring and microbaregraph etc.

1.12.1. Importance and benefits of sound Maintenance systems

H Minimization of down time.

H Life of equipment.

H Safety and smooth operation.

H Backup Supply.

H Reliability.

H Working environment profit.


1.13. QUALITY IN MAINTENANCE

H Quality is defined as the ongoing process of building and

sustaining relationships by assessing, anticipating and

fulfilling stated and implied needs.

H In industrial view, quality is the extent to which product,

processes, services and inter relationships are free from

defects, constraints and items, which do not add value for

customers.

H Quality of a product is concern with performance of the

product at one point of time, usually during manufacturing

process.

H No product can perform reliably without the inputs of

quality control. In other words, quality parts and

components are needed to go into the product so that its

reliability is assured.

1.14. RELIABILITY

H It is typically described as the ability of a component or

system to function at a specified moment or interval of

time.

H Reliability can be also defined as the probability that an

item will continue to perform its intended function without

failure for a specified period of time under stated

condition.


Reliability can be of two types and they are

1. Inherent Reliability.

2. Achievable Reliability.

H Inherent Reliability is associated with the quality of the

material and the design of the machine parts along with

its processing methodologies.

H Achievable Reliability depends upon other factors, such as

maintenance and operation of the equipment.

1.15. DIFFERENCE BETWEEN RELIABILITY AND

QUALITY

H Although both the terms reliability and quality are often

used interchangeably, there is a difference between these

two words.

H The term reliability is concerned with the performance of

a product over its entire lifetime.

H But on the other hand, the term quality is concern with

the performance of a product at one point of time, usually

during the manufacturing process.


1.16. BATHTUB CURVE

H In reliability engineering, this bathtub curve shown in

Fig. 1.1 is widely used, which describes a particular form

of the hazard function that comprises three parts: The first

part is a decreasing failure rate. It is also known as early

failures. The second part is a constant failure rate, known

as random failures. The third part is a increasing failure

rate.


1.17. FAILURE RATE (λ)

Failure Rate is defined as the number of failures occurring

in unit time. It is denoted by ‘λ’. The value of failure rate can

be computed during a specified period for a given number of

components.

As an example, if there are 10 failures occuring during a

period of 1000 hours to which 100 components are subjected,

then

Failure Rate ( λ ) = 10

100 ×

1

1000

= 1 × 10− 4 failures ⁄ hour.

1.17.1. Failure Pattern of Equipment

H The failure pattern of an equipment over its whole life

cycle can be represented in a single curve as shown in

Fig. 1.2.

H In the above figure, Phase 1 shows the failure pattern

inherent in a new product due to manufacturing or design

defects. This phase is also called as the infant mortality

period of equipment.


H Phase 2 shows the useful life period of an equipment

where failure rates are normally moderate as the

equipment gets set to the working environment.

H The last phase is Phase 3 and the failures occur during

this phase fall under the category of wear-out failure that

are caused due to aging of the equipment.

H For the prediction of a system reliability, the above

parameters of the equipment life cycle are very essential.

1.17.2. Mean Time Between Failure (MTBF)

H For a product which is repairable, reliability is quantified

as Mean Time Between Failure (MTBF). Correct

understanding of MTBF is very important. As an example,

a power supply with an MTBF of 40000 hours does not

mean that the power supply should last for an average of

40000 hours.


H An MTBF of 40000 hours, or 1 year for 1 module,

becomes 40000/2 for two modules and 40000/4 for four

modules. Failure rates are sometimes measured in percent

failed per million hours of operation instead of mean time

between failure (MTBF).

1.17.3. Mean Time to Failure (MTTF)

Let us consider,

t1 → Time to failure for the first specimen.

t2 → Time to failure for the second specimen.

⋅ ⋅ ⋅ ⋅ ⋅ ⋅

tn → Time to failure for the nth specimen.

Now, Mean time to failure for n specimen can be calculated

as,

MTTF =

t1 + t2 + ..... tn

n

= 1

n ∑

i = 1

n

ti

H If the numbers of specimen to be tested are more, then it

is very difficult to record the failure for each component.


Thus, instead of recording the failure for each component,

we can record the number which fails during the specific

intervals of time.

If n1 → Number of specimens that failed during the first hour.

n2 → Number of specimens that failed during the second hour.

⋅ ⋅⋅ ⋅⋅ ⋅nk → Number of specimens that failed during the kth hour.

∴ Mean time to failure for n specimens is,

MTTF =

n1 + 2 n2 + 3 n3 + … + knk

n

If time interval is considered as ∆ t, instead of one hour,

Then, MTTF =

n1 ∆ t + 2n2 ∆ t + .... knk ∆ t + .... + ln1 ⋅ ∆ t

n

MTTF =

n1∆t + 2n2∆t + 3n3∆t +....+ knk ∆t +....+ r nr ∆t

n

MTTF = 1

n ∑

k = 1

r

knk ∆ t


1.17.4. Mean Time to Repair (MTTR)

MTTR is the arithmetic mean of the time required to

perform maintenance action. It can be defined as the ratio of total

maintenance time to number of maintenance action.

1.18. SYSTEM RELIABILITY MODEL

H A system is a collection of components, subsystems and

assemblies to a specific design in order to achieve desired

functions with acceptable performance and reliability.

H The types of components, their qualities, quantities and

the manner in which they are assembled within the system

have a direct effect on the system’s reliability.

H The relationship between a system and its components is

often misunderstood or oversimplified.

H As an example, the following statement is not valid: All

of the components in a system have 90% reliability at a

given time, thus the reliability of the system is 90% for

that time. Unfortunately, poor understanding of this

relationship between a system and its constituents can

result in statements like this being accepted as factual,

when in reality they are false.


The various models used for reliability assessment are as

follows,

1.18.1. Series Systems

H A failure of any component leads to the failure of the

entire system in a series configuration.

H In most cases, when complete system at its basic

subsystem level is considered, it is found that these are

arranged reliability-wise in a series configuration.


H As an example, a personal computer may consist of four

basic subsystems: The motherboard, the hard drive, the

power supply and the processor. If failure occurs in any

of these subsystems, it will cause entire system failure.

Thus, all of the units in a series system must succeed for

the entire system to succeed.

Rs = R1 × R2 × R3 × .... × Rn

= ∏

i = 1

n

Ri

where,

R1 , R2 , R3 , .... Rn → Reliabilities of system.

For a pure series system, the system reliability is equal to

the product of the reliabilities of its constituent components.


1.18.2. Parallel Reliability

H In a simple parallel system, as shown in the Fig. 1.7, for

the system to succeed, at least one of the units must

succeed.

H The units in parallel reliability are also referred as

redundant units.

H So in parallel system, all units must fail for the system

to fail.

H In other words, if unit 1 succeeds or unit 2 succeeds or

any one of the units succeeds, then the system succeeds.


H The unreliability of the system is given by,

Rs = 1 − ∏

i = 1

n

1 − Ri

= 1 − ∏

i = 1

n

1 − e− λ it

1.18.3. Combination of Series and Parallel

H When many smaller systems are accurately represented by

either a simple series or parallel configuration, then larger

systems may involve both series and parallel

configurations in the overall system. This type of systems


are analyzed by calculating the reliabilities for the

individual series and parallel sections and then combining

them in the appropriate manner.

1.19. MAINTAINABILITY

H Maintainability is a concept, which closely related to the

characteristic of equipment design and installation.

H It is the probability that a item will remain in a serviceable

condition for a given period of time or restored to a

specified condition within a given period of time.

H Maintainability can be also expressed in terms of the

minimum cost of maintenance as well as the accuracy of

the maintenance functions.

H The main purpose of maintainability is to design the

equipment that can be maintained easily in minimum time

and at minimum cost, which implies that the other

supporting resources such as manpower, spare parts, and

facilities of tools and test equipment must also be minimal.


H To provide the designers with special knowledge related

to the support and maintenance of equipment, the concept

of maintainability was developed.

1.20. AVAILABILITY

H Availability is defined as the ratio of equipments uptime

to the equipments uptime and downtime over a specified

period of time.

H In other words, it is the ratio of the time at which

equipment is available for the desired operation to the total

time of operation and maintenance of equipment.

H The time for which a machine or equipment is actually

available to complete desired function is called uptime of

the machine or equipment.

H The period of time during which a machine or equipment

is not in an acceptable working condition, is called

downtime of the machine or equipment.


H Based on time element, availability is divided into three

types and they are as follows,

(i) Inherent Availability.

(ii) Achieved Availability.

(iii) Operational Availability.

1.20.1. Inherent Availability

The probability that a system or equipment shall operate

satisfactorily when used under prescribed conditions in an ideal

support environment without any scheduled or preventive

maintenance at any given time is called inherent availability.

It can be calculated as follows,

Inherent availability = MTBM

MTBM + MTTR

where,

MTBM → Mean Time Between Failures

MTTR → Mean Time to Failure


1.20.2. Achieved Availability

H The probability that a system or equipment shall operate

satisfactorily when used under prescribed conditions in an

ideal support environment with periodic preventive and

corrective maintenance at any given time is called as

achieved availability.

It can be calculated as follows

Achieved Availability = MTBM

MTBM + M

where,

M → Mean active maintenance downtime resulting

from preventive and corrective maintenance.

1.20.3. Operational Availability

H A certain amount of delay in industrial system can be

always noticed, which is caused by time element such as

supply downtime and administrative down time.

H The probability that a system or equipment shall operate

satisfactorily when used under prescribed conditions in an

actual support environment without any scheduled or


preventive maintenance at any given time is called as

operational availability.

It can be calculated as follows,

Operational Availability = MTBM

MTBM + MDT

where,

MDT → Mean Down Time.

1.21. RELIABILITY, AVAILABILITY AND

MAINTAINABILITY (RAM)

‘RAM’ refers to Reliability, Availability and Maintainability.

H Both reliability and maintainability jointly affect

availability.

H Due to poor maintainability, even a highly reliable

equipment would take more time to be repaired, therefore

it ultimately reduces the availability.

H If maintainability of an equipment is good, but reliability

is poor, then the equipment may fail very frequently.


H The main objectives of RAM analysis are to increase

system productivity, increase the overall profit as well as

reduce the total life cycle cost which includes lost

production cost, operating cost, maintenance cost etc.

1.22. MAINTENANCE ORGANIZATION

H The term organization implies a group of people who

work together in a structured way for a shared purpose.

H In recent industries, various maintenance functions are

planned and executed by workmen of various disciplines

or skills and of different level – such as workmen,

employees, supervisors, executives etc. and they have to

be arranged in such a way that they have to work as a

team towards the common goal of maintenance

effectiveness as well as improvement of equipment

availability and reliability.

H This grouping or arranging of maintenance personnel with

their interlinking and relationships is generally termed as

maintenance organization.

Some of the basic concepts for maintenance organization are

as follows:


(i) To establish reasonably clear division of authority with

minimum overlap: Authority can be divided functionally,

geographically, on the basis of expediency or it can be on some

combination of all the three. But clear definition of the line of

demarcation (boundary) must be there to avoid confusion and conflict.

(ii) To keep vertical line of authority and responsibility as

small as possible: Unclear or many levels of intermediate

supervision or over application of specialized functional

employees must be minimized. If necessary, clear division of

duties must be established for such practices.

(iii) To maintain an optimum number of people reporting to

one individual: In a good organization, depending on the type

of job, number of people reporting to one individual may vary

from 3 to 6.

(iv) To avoid conflicts amongst workers, the total maintenance

workload should be reasonably distributed amongst all concerned

person in an organization.

(v) Maintenance is not subordinate to operation and the difference

between ‘supportive service’ and ‘subordinate service’ should be

kept in mind.


Some factors governing the maintenance organization are as

follows:

(a) Types of operation: eg: machine tool, process equipment

etc.

(b) Continuity of operation.

(c) Geographical location.

(d) Equipment’s age and condition.

(e) Size of plant / industry.

(f) Scope of plant maintenance engineering department.

(g) Employees level of training and reliability.

(h) Complexity of business and machines and extent of

automation and built in test and monitoring equipments

provided.

(i) Prevailing maintenance types or systems of the industry.

(j) Extent of outsourcing available or permissible.

(k) Local labour laws and prevailing industrial culture and

practices.


1.22.1. Objectives of Maintenance Organization

The following are some of the objectives of maintenance

management:

(i) To minimize the repair time and repair cost.

(ii) To minimize the loss of productive time because of

equipment failure.

(iii) Efficient use of maintenance personnel and equipments.

(iv) To keep all productive assets in good working conditions.

(v) To minimize the loss due to production stoppages.

(vi) To maximize efficiency and economy in production

through optimum use of facilities.

(vii) To improve the quality of products and to improve

productivity.

(viii) Prolonging the life of capital assets by minimizing the

rate of wear and tear.

(ix) To minimize the total maintenance cost which includes

the cost of repair, cost of preventive maintenance and

inventory carrying costs, due to spare parts inventory.

(x) To minimize accidents through regular inspection and

repair of safety devices.


1.22.2. Types of Maintenance Organization

Maintenance Organization may be classified into following

ways:

(i) Line and staff organizations.

(ii) Functional organizations.

(iii) Centralized and decentralized organizations.

1.22.3. Line and Staff Organization

H Line Organization is the simplest and the oldest type of

organization. In this type of organization, top management

has complete control and the chain of command is clear

and simple. The line of command is carried out from top

to bottom. Due to this line organization is also called as

scalar organization.

Some of the features of line organizations are

(i) It is the most simplest form of organization.

(ii) Line of authority flows from top to bottom.

(iii) Specialized and supportive services do not take place in

these organizations.


(iv) Unified control by the line officers can be maintained

since they can independently take decisions in their

respective areas.

H Line and staff organization is a modification of line

organization and it is not as simple as line organizations.

Staff positions serve the organization by indirectly

supporting line functions. Staff positions consist of staff

personnel and staff managers.

H Staff personnel use their technical expertise to assist line

personnel and help top management in various business

activities. On the other hand, staff managers provide

support, advice and knowledge to other individuals in the

chain of command. Although staff managers are not part

of the chain of command related to direct production of

products or services, they do have some authority over

personnel.

Some features of line and staff organizations are as follows:

(i) There are two types of staff

Staff Assistants : P.A. to Managing Director,

Secretary to Marketing

manager.

Staff Supervisor : Operation control manager,

Quality controller, PRO.


(ii) Line and staff organization is more complex than line

organization.

(iii) Division of work and specialization takes place in line

and staff organization.

(iv) The whole organization is decided into different

functional areas to which staff specialists are attached.

(v) Efficiency can be achieved through the features of

specialization.

(vi) Power of command remains with the line executive and

staff serves only as counselors.


1.22.3.1. Advantages of Line and Staff Organization

(i) Relief to line of executives: In a line and staff organization,

the advice and counseling which is provided by the staffs to the

line executive will give them relief of dividing their attention to

many areas.

(ii) Expert advices: Line and staff organization facilitates expert

advice to the line executive at the time of need.

(iii) Benefits of specialization: Line and staff through division

of whole concern into two types of authority divides the

organization into parts and functional areas. This way, every

officer or official can concentrate in their own area.

(iv) Better co-ordination: Line and staff organization, through

specialization, is able to provide better decision making and

concentration remains in few hands.

(v) Benefits of Research and Development: With the help of

the advice of specialized staff, the line executives get time to

execute plans by taking productive decisions. This give a wide

scope to the line executive to bring innovations and go for

research work in these areas.


(vi) Training: The presence of staff specialists and their expert

advice serves as ground for training to line officials.

(vii) Unity of action: It is the result of unfield control. Control

and its effectivity take place when co-ordination is present in the

concern.

1.22.3.2. Disadvantages of Line and Staff Organization

(i) Conflict between line and staff authorities

H There may be chances of conflict between line and staff

authorities. Sometimes line officers resent the activities of

staff members on the plea that they donot always give

correct advice. Similarly, sometimes staff officials

complain that their advice is not properly carried out.

(ii) Problem of line and staff authority

H There might be confusion on the relationship of line and

staff authorities. Sometimes line officers consider

themselves superior to staff officer which is objected by

staff officers.

(iii) Lack of Responsibilities

H Since the staff specialists are not accountable for the

results, they may not perform their duties well.


(iv) Costly

H The appointment of experts involves a heavy expenditure

which can not be afforded by small and medium size

organizations.

1.22.4. Functional Organization

H In this type of organization, the arrangement of

maintenance personnel are done by the type of functions

they perform. This type of organization is basically not

individual based, but it is based on the functional areas,

which highlights the functional working arrangement in an

industry.

Some features of functional organizations are as follows:

(i) All organizational activities are divided into specific

functions such as operation, finance, marketing and

personal relations.

(ii) Complex form of administrative organization compared to

the other two organization types.

(iii) Three authorities exist line, staff and function.


(iv) Each functional area is put under the charge of functional

specialists and they have got the authority to give all

decisions regarding the function whenever the function is

performed throughout the organization.

(v) Principle of unity of command does not apply to such

organization as it is present in line organization.

1.22.4.1. Advantages of Functional Organization

(i) Specialization: Better division of labour takes place

which results in specialization of function and it’s

consequent benefit.

(ii) Effective Control: Management control is simplified as

the mental functions are separated from manual function.


(iii) Efficiency: As each functional performs a limited number

of functions, greater efficiency can be achieved.

(iv) Economy: Specialization compiled with standardization,

which facilitates maximum production and economical

costs.

(v) Expansion: Expert knowledge of functional manager

facilitates better control and supervision.

1.22.4.2. Disadvantages of Functional Organization

(i) Confusion: The functional system is quite complicated to

put into operation, especially when it is carried out at

low levels. Thus, co-ordination becomes difficult.

(ii) Lack of Co-ordination: As workers are commanded not

by one person but a large number of people, the

disciplinary control becomes weak and there is no unity

of command.

(iii) Difficulty in fixing responsibility: It is very difficult to

fix responsibilities due to multiple authority.

(iv) Conflicts: There may be conflicts among the supervisory

staff of equal ranks and sometimes they may not agree

on certain issues.


(v) Costly: Maintenance of specialist’s staff of higher order

is expensive for a concern.

1.22.5. Central ized and Decentral ized Maintenance

Organization

H A centralized organization is structured by a strict

hierarchy of authority. Here, most of the decisions are

made at the top by one or a few individuals. Informations

from lower levels flow up to the decision maker, where

the information is analyzed and synthesized to gain a

broader perspective in order to help in decision making.

On the other hand, informations flow down to provide

directions to the lower levels of the hierarchy where lower

levels are expected to implement the decisions.

H Centralized maintenance organization may be of two types

and they are pure and amalgamated. In pure centralized

maintenance organization, the employees of individual

disciplines ultimately report to chief of that discipline and

those individual chiefs further report to head of plant.

H On the other hand, in amalgamated centralized

maintenance organization, the lower level of individual

disciplines may report to area in-charge of maintenance,


who may be of any of those disciplines and this area

in-charge will report to chief of plant maintenance.

1.22.5.1. Advantages of Centralized Maintenance

Organization

(i) Problems can be easily investigated.

(ii) Skill and technology easily disseminated.

(iii) Excel in planning and scheduling.

(iv) Costly and specialized equipments can be procured and

used more effectively.

(v) More specialized supervision, when needed.

(vi) Generally more cost effective.

1.22.5.2. Disadvantages of Centralized Maintenance

Organization

(i) The hierarchical nature of the organization often hinders

innovation and creativity.

(ii) Incomplete collection of operating data.

(iii) Higher transportation cost.

(iv) More time getting to and from work area.


H A decentralized maintenance organization is one in which

most decisions are made by mid-level or lower level

managers, rather than being made centrally by the head

of the company.

H The decentralized maintenance organizations are based on

two components. (i) One is discipline wise decentralization

(ii) Other is area-wise decentralization.

1.22.5.3. Advantages of Decentralized Maintenance

Organization

(i) Good communication with operating department.

(ii) Speedy maintenance response and reduced travel time.

(iii) Interchangeability of operation maintenance workforce

even at managerial level is also possible.

(iv) Conflict amongst workmen is reduced due to better

co-ordination.

(v) Better familiarity with machines and process.

1.22.5.4. Disadvantages of Decentralized Maintenance

Organization:

(i) It requires more people.

(ii) Non-availability or under-utilization of specialized tools

and facilities.


(iii) Difficulty in sharing technology and skills.

(iv) Generally more costly due to duplication of tools and

facilities.

H As centralized or decentralized organization is not suitable

for all types of organizations, the concept of partially

Decentralized or Mixed organization is also used. The

partially Decentralized organization is modified type of

centralized organization, which is more suitable for bigger

plants or plants having units at far away places. In such

organizations, the maintenance personnel attached to

production unit, carry out day-to-day maintenance, routine

maintenance and most emergency jobs.

H Important maintenance functions such as overhauling,

planned maintenance, major jobs, procurement of spare

etc. are kept under the charge of chief maintenance

engineer, who will look after all the central and captive

shops, maintenance planning, drawing and documentation.

1.22.5.5. Advantages of Partially Decentralized Organization

(i) Good communication with operating department.

(ii) Skills and technology dissemination and problem

investigation easier.


1.22.5.6. Disadvantages of Partial ly Decentralized

Organization

(i) Job rotation requires ingenuity.

(ii) Management is somewhat difficult.

1.23. MAINTENANCE ECONOMICS

Life Cycle Cost Analysis

H Life cycle costing is used to determine the most cost

effective option among different competing alternatives.

H It is the cost analysis for the equipment in industry that

accounts the total cost of equipment over a span of time

which includes the capital cost, operating cost and

maintenance costs.

H Life cycle cost analysis is the integration of engineering,

economic and financial strategies in relation to the

equipment to be purchased.

H The aim of this analysis is to ascertain the total cost of

equipment over the span of its entire life period.


Advantages:

H The main advantage is the selection of an equipment of

lower operating and maintenance costs resulting in reduced

cost of ownership.

H The money saved can be used for various works in the

industry.

Estimation of economic life of equipment

H The economic life of equipment can be estimated by

plotting the cumulative efficiency and maintenance and

repair cost per cumulative hour against operating hours.

H It mainly depends on the maintenance and repair costs,

availability and operational efficiency.

Maintenance Cost

H Budgets are generally allocated for each type of activity

during the planning stage.

H It must also include the maintenance cost.


H The maintenance cost is difficult to set because of random

failures.

H The maintenance cost directly depends on the level of

maintenance and its requirements.

Components of Maintenance Cost

There are two components:

(i) Field cost : It includes the cost of support

including the maintenance staff.

(ii) Variable cost : It includes the consumption of spare

parts, replacement of components and

other facilities cost.

Impact of Maintenance cost

H It may differ from one organization to another depending

up on the importance attached to the maintenance

function.

H The maintenance cost does not have any relation with the

production cost.

H It can be minimum during peak production months and

very high during low production periods.


1.23.1. Maintenance Budgeting

H A budget is a financial plan, forecast of expenditure and

revenues for a specified period of time. In other words, a

budget is the some of money allocated for a particular

purpose and the summary of intended expenditures along

with proposal for how to meet them.

H To control maintenance costs, budgeting of maintenance

cost is very important because maintenance is a service

organization and probably no better way is available to

control its cost.

1.23.2. Types of Maintenance Budgeting

H Maintenance budget are of two types and they are

Revenue and Capital.

H If it is further classified, following three types can be

observed.

(i) Appropriation budgets: Which sets a lumpsum as the

maximum amount that can be spent for a given item.

(ii) Fixed budget: Which specifies the allowable amount of cost

for a period of time.

(iii) Flexible budget: Which relates the allowable cost to some

measure of activity.

1.23.3. Preparation of Maintenance Budget

In preparation of maintenance budget, usually three basic

approaches are used and they are as follows:

(i) Allocate revenue and expenses using top-down/bottom up,

(or) Production/maintenance Schedule Approach.


(ii) Labour Allocation Approach.

(iii) Integrated approach.

H All these three approaches are self explanatory.

Individually, the production or maintenance approach and

labour allocation approach may not be very precise as

working alone.

H Both approaches may face some uncertainties such as

hidden waiting time from one process to another, variation

in skill requirements and skill available etc. Due to this,

a combination of integrated approach is often used for

preparation of the maintenance budget. It includes some

cash budget for contingent expenditures which may come

up unexpectedly.

1.23.4. Advantages of Maintenance Budgeting

(i) It improves the system effectiveness and also increase the

efficiency of maintenance organization.

(ii) As maintenance personnel know their budget in advance,

they can plan their expenditures judiciously and timely

so that no job is held up for shortage of funds.

(iii) It is very effective technique for projecting future as well

as additional requirements of fund.

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