Principles and practices of maintenance planning

PRINCIPLES AND PRACTICES OF
MAINTENANCE PLANNING
By : Mudit M. Saxena
Dept. Of Mech. Engg.

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
Principles and Practices of
Maintenance Planning
2By: Mudit M. Saxena, Dept. of Mech. Engg.

MAINTENANCE
ENGINEERING
 It is the art that is intended to retain a machine or an
equipment or restore it to, a state in which it can perform a
required function or an operation.
 It is the discipline and profession of applying engineering
concepts to the optimization of equipments, procedures to
achieve better reliability and availability of equipments.
 It is the art, science and philosophy that aides in increased
productivity and has become the most important component
of plant maintenance.

 In general,
All actions necessary for retaining an item, or restoring
to it, a serviceable condition, include servicing, repair,
modification, overhaul, inspection and condition
verification.
 Increase availability of a system.
 Keep system’s equipment in working order are the main
role of maintenance Engineering.
Maintenance Engineering

PURPOSE OF MAINTENANCE
 The main purpose of maintenance in an industrial
perspective is to reduce the business risks.
 Production capacity, productivity and business profit mainly
depends on maintenance operations.
 Its main purpose is to support ,configure, diagnose , repair,
update and mange a equipment throughout it’s life cycle.
 In general maintaining all equipments at its full functionality
and helping productivity is the main function of
maintenance engineering.
1. Attempt to maximize performance of production
equipment efficiently and regularly.
2. Prevent breakdown or failures.
3. Minimize production loss from failures.
4. Increase reliability of the operating systems.

PRINCIPLE OBJECTIVES IN
MAINTENANCE
1. To achieve product quality and customer satisfaction through
adjusted and serviced equipment.
2. Maximize useful life of equipments.
3. Keep equipments safe and prevent from hazards.
4. Minimize frequency and severity of interruptions.
5. Maximize production capacity – through high utilization of facility.

 Maintenance planning consists of set of tasks of organizing
resources to carry out a job satisfactorily at reasonable cost
within a specified period of time.
It involves
 Assignment of jobs to the crew on the basis of job scheduling.
 Also ensures methods to tackle emergency maintenance
 It ensures smooth operation of the system.

Main classification of planning in engineering system are as
follows,
1. Long range planning
2. Short range planning
3. Planning for immediate activity
1. Long Range planning : for a period of five years at least.
Involves capital budgeting, strategies and operational
programmers.
2. Short range: up to one year. Made to achieve short term
goals.
3. Immediate Activity Planning : it is done frequently whenever
required.

OBJECTIVES OF MAINTENANCE PLANNING
Some important objectives are
 Maximising production or increasing facilities availability at the
lowest cost and at the highest quality and safety standards.
 Reducing breakdowns and emergency shutdowns.
 Optimising resources utilisation.
 Reducing downtime.
 Improving spares stock control.
 To keep time schedule of delivery to the customers.
 To control the cost of maintenance related activities.
 Improving equipment efficiency and reducing scrap rate.
 Minimising energy usage.
 Optimising the useful life of equipment.
 Identifying and implementing cost reductions.
 To provide effective and trained supervision.

They are followed in a system to guide the staff to work
efficiently and effectively to achieve the overall objectives
of the maintenance system,
Main areas of work governed by this principles are
 Plant management in Maintenance work
 Production and maintenance objectives
 Establishment of work order and recording system
 Information based Decision making
 Adherence to planned maintenance strategy .
 Manpower for Maintenance
 Planning for maintenance functions
 Role of Spare parts
 Training.
Principles of Maintenance :

SOUND MAINTENANCE SYSTEM-
IMPORTANCE
 Profit depends mainly on return on the investments.
 Higher investments- possible –machineries and equipments in
proper working condition.
Some benefits of sound maintenance are,
 Minimization of downtime
 Provide Adequate back up supply
 Extended life of equipment
 Increased reliability of the system
 Safety of the personal involved.

Machine Failures

RELIABILITY
Reliability may be defined in several ways:
 The idea that an item is fit for a purpose with respect to
time.
 In the most practical sense: "Items that do not fail in use
are reliable" and "Items that do fail in use are not reliable".
 The capacity of a designed, produced or maintained item
to perform as required over time.
 The resistance to failure of an item over time.

 The probability of an item to perform a required function
under stated conditions for a specified period of time.
 In line with the creation of safety cases for safety, the goal
is to provide a robust set of qualitative and quantitative
evidence that an item or system will not contain
unacceptable risk.
 The basic sorts of steps to take are to:
 First thoroughly identify as many as possible reliability
hazards (e.g. relevant System Failure Scenarios item
Failure modes, the basic Failure mechanisms and root
causes) by specific analysis or tests.
 Assess the Risk associated with them by analysis and
testing.
RELIABILITY
16
By: Mudit M. Saxena, Dept. of Mech. Engg.

 Propose mitigations by which the risks may be lowered
and controlled to an acceptable level.
 Select the best mitigations and get agreement on final
(accepted) Risk Levels, possible based on cost-benefit
analysis.
RELIABILITY THEORY
 Reliability is defined as the probability that a device will
perform its intended function during a specified period of
time under stated conditions.
 Mathematically, this may be expressed as,
Where is the failure probability density function and
is
the length of the period of time (which is assumed to start
from time zero).
RELIABILITY

MEASURES FOR MAINTENANCE
PERFORMANCE
 MEAN TIME BETWEEN FAILURES (MTBF)
 MTTR (Mean time to repair)

 Mean time between failures (MTBF) is the
predicted elapsed time between inherent
failures of a system during operation. MTBF
can be calculated as the arithmetic mean
(average) time between failures of a system.
MEAN TIME BETWEEN FAILURES
(MTBF)

 The MTBF is often denoted by the Greek
letter θ, or
 The MTBF can be defined in terms of the
expected value of the density function ƒ(t)
where ƒ is the density function of time until
failure – satisfying the standard requirement
of density functions
MEAN TIME BETWEEN
FAILURES (MTBF)

MEAN TIME BETWEEN FAILURES
(MTBF)

 MTBF value prediction is an important
element in the development of products.
Reliability engineers / design engineers,
often utilize Reliability Software to calculate
products' MTBF according to various
methods/standards (MIL-HDBK-217F,
Telcordia SR332, Siemens Norm,
FIDES,UTE 80-810 (RDF2000), etc.).
MEAN TIME BETWEEN FAILURES (MTBF)

 The M can stand for any of minimum, mean or
maximum, and the R can stand for any of
recovery, repair, respond, or restore.
 The most common, mean, is also subject to
interpretation, as there are many different ways
in which a mean can be calculated.
 Mean time to repair
 Mean time to recovery/Mean time to restore
 Mean time to respond
 Mean time to replace
MTTR (Mean time to repair)

 Mean time to repair (MTTR) is the average
time required to troubleshoot and repair failed
equipment and return it to normal operating
conditions.
 It is a basic technical measure of the
maintainability of equipment and repairable
parts.
 Maintenance time is defined as the time
between the start of the incident and the
moment the system is returned to production
(i.e. how long the equipment is out of
production).

 This includes notification time, diagnostic time,
fix time, wait time (cool down), reassembly,
alignment, calibration, test time, back to
production, etc..
 Mean time to repair ultimately reflects how well
an organization can respond to a problem and
repair it.

 Expressed mathematically, it is the total maintenance time
divided by the total number of maintenance actions over a
specific period.
 Over the lifetime of an asset, each failure will vary depending on
the severity of the issue.
 Some issues will require a simple parts swap, while others could
take days to diagnose and repair.
 Prediction of the number of hours that a system or component
will be unavailable whilst undergoing maintenance is of vital
importance in reliability and availability studies.
 Mean time to repair yields a lot of information that can help
reliability engineers make informed decisions such as repair or
replace, hire, optimize maintenance schedules,

Mean Waiting Time
The mean waiting period for a actual repair to
begin is known as mean waiting time.
Maintenance Action Rate
It is the number of maintenance action that can
be carried out on an equipment per hour.
µ = 1÷MTTR

3. MAINTAINABILITY ,
AVAILABILITY:
Maintainability :
 It is can be defined as the probability that a
system or a unit will be restored to specific
working conditions within a given period, when
maintenance action is taking place.
- As per accordance with prescribed procedures
and resources.
- It includes minimum cost as well as accuracy.

AVAILABILITY
 It is the ratio of the time at which equipment is available for
the designated operations to the total time of operation and
maintenance of the equipment.
- Ratio of equipment uptime to downtime over a specified
period of time.
Availability Classifications
 Instantaneous (or Point) Availability
 Average Uptime Availability (or Mean Availability)
 Steady State Availability
 Inherent Availability
 Achieved Availability
 Operational Availability

Instantaneous or Point Availability, A(t)
 Instantaneous (or point) availability is the
probability that a system (or component) will be
operational (up and running) at a specific
time, t.
 This classification is typically used in the
military, as it is sometimes necessary to
estimate the availability of a system at a
specific time of interest (e.g., when a certain
mission is to happen).
Availability

AVAILABILITY
Average Uptime Availability (or Mean
Availability),
 The mean availability is the proportion of
time during a mission or time period that the
system is available for use. It represents the
mean value of the instantaneous availability
function over the period (0, T) and is given
by:

Steady State Availability, A(∞)
 The steady state availability of the system is
the limit of the availability function as time
tends to infinity. Steady state availability is
also called the long-run or asymptotic
availability. A common equation for the
steady state availability found in literature
is:
Availability

Inherent Availability :
It is the probability that a system or equipment will operate
satisfactorily when used under a prescribed conditions
without any scheduled or preventive maintenance at any
given time.
Inherent Availability= MTBM/MTBM+MTTR
Achieved Availability :
It is the probability that a system or equipment will operate
satisfactorily when used under a prescribed conditions
with any scheduled or preventive maintenance at any
given time.
Achieved Availability = MTBM/MTBM+M
Availability

AVAILABILITY
Operational Availability :
In industry, a certain downtime always take
place due to supplies or administrative
works etc.,
It is the probability that a system or equipment
will operate satisfactorily when used under a
prescribed conditions in an actual
environment without any scheduled or
preventive maintenance at any given time.
Operational Availability= MTBM/MTBM+MDT

EQUIPMENT LIFE CYCLE
 The equipment lifecycle begins from the time equipment is requested through its
retirement from service and typically consist of three phases: Acquisition, Use, and
Retirement

 Acquisition
 Capital equipment is acquired for a variety of purposes including performing
research, patient care, and university operations. It is also obtained through a variety
of methods such as direct purchase, gifts of equipment, fabrication, transfers-in
from other institutions, government furnished equipment, loaned equipment, capital
lease, or equipment purchased under construction contract. Capital equipment is
tracked, recorded, and inventoried via the ARC Asset Management module. When
the equipment purchase goes through the Accounts Payable module the asset is
integrated into the ARC Asset Management module. All other methods of
procurement are integrated into the ARC Asset Management module through
processes managed by Capital Asset Accounting. Capturing the acquisitions at
inception allows the University to record the cost of the asset and track its location.


EQUIPMENT LIFE CYCLE
 Use
 University capital equipment is intended for institutional use and not for
private purposes. Use may be further restricted if acquired under a gift,
grant, or contract as dictated by the terms. Individuals requesting home use
(for institutional purposes) of equipment must obtain the approval of the
Senior Business Officer and notify CAA that the equipment will be used
offsite. Equipment is considered in use until such time as it is retired.
 Retirement
 An asset retirement occurs when the equipment is no longer functioning as
intended, is lost or stolen, sold, traded-in, donated to an external party, or
disposed in some other fashion. Equipment acquired under a gift, grant, or
contract may have specific disposal restrictions which the University must
adhere to. This information is normally found in the sponsor agreement or
donation documentation. Additionally, radioactive equipment has specific
regulations that control its disposal.

38
WHAT IS EQUIPMENT LIFE CYCLE?
Commission
Operate
Maintain
Retire / Replace
Design
Construct
Equipment & Asset
Life-Cycle

MAINTENANCE ORGANISATION
It’s Classification are
De-Centralized Maintenance:
 This model is the most common.
 Here, you have a self-standing facility management organization and
structure for each of the major business groups:
 The Central Plant, which handles major heating and cooling, electrical, and
possibly the roads, grounds, and sidewalks;
 A Central Facility Group, which handles classroom and office buildings,
including electrical, HVAC, plumbing, and structures,
 These individual groups often have separate capital programs, purchasing
and supply systems, fleets, maintenance teams and contractors.
 They typically enjoy higher customer satisfaction than do those in a
centralized structure, as well as a better team attitude and ownership

Centralized :
 The centralized organization brings all of the facility
management and maintenance groups into one organization, so
control of standards and procedures becomes consistent across
the entire organization.
 A centralized approach undoubtedly is more efficient, the quality
of repairs and installations is higher, and more consistency
exists in the approach to asset and equipment reliability.
 The most common negative is typically a reduction in customer
satisfaction. To address this challenge, the leadership team of
the program and process must be very strong and have best-in-
class performance measures in place so everyone can easily see
even the most subtle changes in performance.
MAINTENANCE ORGANISATION

 Partially Localized/ Centralized Planning:
Suppose there five plants in an
organization. For three plants they
have central planning plant and for rest
other two they have local planning. Such
type of Maintenance Planning is known as
Partially Centralized Maintenance Planning.
Partially Localized/
Centralized Planning:

TWO TYPES OF ORGANIZATION
Line organization is the most oldest and simplest method
of administrative organization.
 According to this type of organization, the authority
flows from top to bottom in a concern.
 The line of command is carried out from top to bottom.
This is the reason for calling this organization as scalar
organization which means scalar chain of command is a
part and parcel of this type of administrative
organization
 In this type of organization, the line of command flows
on an even basis without any gaps in communication
and co-ordination taking place.

Features of Line Organization
 It is the most simplest form of organization.
 Line of authority flows from top to bottom.
 Specialized and supportive services do not take
place in these organization.
 Unified control by the line officers can be
maintained since they can independently take
decisions in their areas and spheres.
 This kind of organization always helps in
bringing efficiency in communication and
bringing stability to a concern.
TWO TYPES OF ORGANIZATION

 Simplest- It is the most simple and oldest
method of administration.
 Unity of Command- In these organizations,
superior-subordinate relationship is maintained
and scalar chain of command flows from top to
bottom.
 Better discipline- The control is unified and
concentrates on one person and therefore, he
can independently make decisions of his own.
Unified control ensures better discipline.
.
Merits of Line Organization

 Fixed responsibility- In this type of organization,
every line executive has got fixed authority, power
and fixed responsibility attached to every authority.
 Flexibility- There is a co-ordination between the top
most authority and bottom line authority. Since the
authority relationships are clear, line officials are
independent and can flexibly take the decision. This
flexibility gives satisfaction of line executives.
 Prompt decision- Due to the factors of fixed
responsibility and unity of command, the officials
can take prompt decision

 Over reliance- The line executive’s decisions are implemented to
the bottom. This results in over-relying on the line officials.
 Lack of specialization- A line organization flows in a scalar chain
from top to bottom and there is no scope for specialized
functions. For example, expert advices whatever decisions are
taken by line managers are implemented in the same way.
 Inadequate communication- The policies and strategies which
are framed by the top authority are carried out in the same way.
This leaves no scope for communication from the other end. The
complaints and suggestions of lower authority are not
communicated back to the top authority. So there is one way
communication.

 Lack of Co-ordination- Whatever decisions
are taken by the line officials, in certain
situations wrong decisions, are carried down
and implemented in the same way.
Therefore, the degree of effective co-
ordination is less.
 Authority leadership- The line officials have
tendency to misuse their authority positions.
This leads to autocratic leadership and
monopoly in the concern.

LINE AND STAFF ORGANIZATION
 Line and staff organization is a modification of line
organization and it is more complex than line
organization.
 According to this administrative organization,
specialized and supportive activities are attached to
the line of command by appointing staff supervisors
and staff specialists who are attached to the line
authority.
 The power of command always remains with the line
executives and staff supervisors guide, advice and
council the line executives. Personal Secretary to
the Managing Director is a staff official.

It’s Benefits :
 Relief to line of executives- In a line and staff organization, the
advice and counseling which is provided to the line executives
divides the work between the two. The line executive can
concentrate on the execution of plans and they get relieved of
dividing their attention to many areas.
 Expert advice- The line and staff organization facilitates expert
advice to the line executive at the time of need. The planning and
investigation which is related to different matters can be done by
the staff specialist and line officers can concentrate on execution
of plans.
 Benefit of Specialization- Line and staff through division of whole
concern into two types of authority divides the enterprise into
parts and functional areas. This way every officer or official can
concentrate in its own area.
Line and staff organization

 Better co-ordination- Line and staff organization through
specialization is able to provide better decision making and
concentration remains in few hands. This feature helps in bringing
co-ordination in work as every official is concentrating in their own
area.
 Benefits of Research and Development- Through the advice of
specialized staff, the line executives, the line executives get time
to execute plans by taking productive decisions which are helpful
for a concern. This gives a wide scope to the line executive to
bring innovations and go for research work in those areas. This is
possible due to the presence of staff specialists.
 Training- Due to the presence of staff specialists and their expert
advice serves as ground for training to line officials. Line
executives can give due concentration to their decision making.
This in itself is a training ground for them.

 Balanced decisions- The factor of specialization
which is achieved by line staff helps in bringing
co-ordination. This relationship automatically
ends up the line official to take better and
balanced decision.
 Unity of action- Unity of action is a result of
unified control. Control and its effectivity take
place when co-ordination is present in the
concern. In the line and staff authority all the
officials have got independence to make
decisions. This serves as effective control in the
whole enterprise

ORGANISATION STRUCTURE OF
MAINTENANCE DEPARTMENT
Maintenance
Superintendent
Facilities
Foreman
Foreman Shops
Maintenance
Foreman
Planning
Maintenance
Foreman
Engineering
Field Foreman
Engineering
Assistant or
Technician

Facilities Foreman
 Air Conditioning
 Water Supply
 Steam
 Power Required.
Shops Maintenance
 Maintenance of Machines/Equiments
 Repair
 Lubrication

Foreman Planning and Maintenance
 Work order system
 Scheduling
 Backlogs Control
 Performance Reports
Field Foreman
 Buildings
 Yards
 Fire Protection
 Waste Disposal

MAINTENANCE ECONOMICS
Life Cycle Cost Analysis
The factors to be considered in the purchase of
equipment for industries include the cost, quality,
performance and maintenance requirements.
Life cycle costing is the cost analysis for the
equipment over a span of time which includes the
capital cost, operating cost and maintenance
costs.
It leads to selection of proper and economically
viable equipment.

 Maintenance cost :
-difficult to measure due to random nature of
failures.
-records on maintenance history can be used .
Component of Maintenance Cost :
Fixed cost and Variable cost :
Fixed includes the cost of support facilities,
including the maintenance staff.
Variable cost includes the consumption of
spare parts, components replacements etc.,

ASSIGNMENT - 10
Q 1. What is the purpose of maintenance ?
Q 2. Write the principle objectives of maintenance.
Q 3.What is maintenance planning ? Write the objectives of maintenance planning.
Q 4. What are the benefits of sound maintenance ?
Q 5. Explain reliability.
Q 6. Explain “Mean time between failures” i.e. MTBF
Q 7. Explain “mean time to repair” i.e. MTTR
Q 8. Explain maintainability and availability.
Q 9. What is equipment life cycle ? Explain.
Q 10. Explain classification of Maintenance Organization.
Q 11. Explain line organization. Write its features and merits.
Q 12. Explain line and staff organization. Write its benefits.
Q 13. Draw organization structure of maintenance department.
Q 14. Explain maintenance economics.
By: Mudit M. Saxena, Dept. of Mech. Engg. 57

Principles and practices of maintenance planning

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