RAMCO INSTITUTE OF TECHNOLOGY
Mr.M.LAKSHMANAN
Assistant Professor (Senior Grade)
Department of Mechanical Engineering

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.

Maintenance
Approach
Planned
Maintenance
Preventive
Maintenance
Corrective
Maintenance
Predictive
Maintenance
Condition
Based
Maintenance
Reliability
Central
Maintenance
Breakdown
Maintenance

Breakdown / Reactive Maintenance
• The equipment is allowed to operate till no
failure occurs. No maintenance work is
carried out in advance to prevent the failure.
• The people wait till equipment fails and
repair.
• Its ineffective and extremely expensive.
• Poor planning and incomplete repair will be
contributed for high maintenance cost.

Limitations of Reactive Maintenance
• Most repairs are poorly planned due to time
constraint caused by production and plant
management.
• This approach focus only on repair or the
symptoms of failure and not on the root
cause of failure.

Planned Maintenance
• Corrective Maintenance:
Its focused on regular planned tasks that will
maintain all critical machinery and system
in optimum operating conditions.
Main Objectives:
1. Eliminate breakdowns
2. Eliminate deviations from optimum
operating conditions.
3. Eliminate unnecessary repairs
4. Optimize all critical plant systems.

• Corrective maintenance can be defined as
a maintenance task performed to identify,
isolate, and rectify a fault so that the failed
equipment, machine, or asset can be
restored to an operational condition within
the tolerances
• Corrective maintenance is maintenance
which is carried out after failure detection
and is aimed at restoring an asset to a
condition in which it can perform its
intended function.

Preventive Maintenance
• It is the maintenance program which is
committed to the elimination or prevention of
corrective and break down maintenance.
• It involves periodical evaluation of critical
equipment, machinery to detect problem and
schedule maintenance task to avoid
degradation in operating conditions.
• Its designed for day to day maintenance like
cleaning, inspection, lubricating, retightening
etc., to retain the healthy condition of
equipment.

Benefits of Preventive Maintenance
• It maintains the equipment in good
condition to preventing them from bigger
problems.
• Prolongs the effective life of the equipment.
• Detect the problem at earlier stages.
• Minimize / eliminates the rework.
• Reduces unplanned downtime.

Predictive Maintenance
• It is a management technique that uses
regular evaluation of the actual operating
conditions of plant equipment, production
systems and total plant operation.
• Predictive maintenance as regard to
maintenance management, based on need,
will provide necessary data for scheduling
of preventive and corrective maintenance
tasks.

• Predictive maintenance (PdM) techniques are
designed to help determine the condition of in-
service equipment in order to predict when
maintenance should be performed. This approach
promises cost savings over routine or time-based
preventive maintenance, because tasks are
performed only when warranted.

Its helps to improve/increase,
• The production capacity
• Product quality
• Overall effectiveness of production function.
Benefits of predictive Maintenance:
• Reduced breakdown losses
• Reduction of Quality defects
• Increased net operating profit
• Reduced maintenance cost

Condition Based Maintenance
• Condition-based maintenance (CBM),
shortly described, is maintenance when
need arises. This maintenance is performed
after one or more indicators show that
equipment is going to fail or that equipment
performance is deteriorating.

Condition Based Maintenance Techniques
• Vibration Monitoring:
Determines the actual condition of
equipment/machines by studying the noise or
vibration produced during functioning.
• Thermography:
Determines the condition of plant machinery,
system etc. by studying the emission of infra
red energy ( Temperature)

• Tribology:
Determines the dynamic condition of bearing
lubrication, rotor support structure of
machinery etc. by adopting any one of the
techniques like lubricating oil analysis and
wear particle analysis.
• Electrical motor Analysis
Determines the problem within motors and
other equipments.
• Visual inspection:
Determines the conditions of working
elements visually based on the experience.

Reliability Centered Maintenance (RCM)
• RCM is one of the well established
systematic and a step by step instructional
tool for selecting applicable and appropriate
maintenance operation types.
• It helps in how to analyze all failure modes
in a system and define how to prevent or
find those failures early.

The rough process of RCM is as follows:
• Target products or systems of maintenance
should be clearly identified, and necessary
data should be collected.
• All possible failures and their effect on
target products or systems are
systematically analyzed.

Applications of RCM
• When designing, selecting and installing
new systems in a plant
• When setting up preventive maintenance for
complex equipment and systems for which
are not clear on how they work.

Total Productive Maintenance (TPM)
• In industry, total productive maintenance
(TPM) is a system of maintaining and
improving the integrity of production and
quality systems through the machines,
equipment, processes, and employees that
add business value to an organization.
• It’s a maintenance program which involves a
newly defined concept of maintaining plants
and equipments.

• To increase the production, at the same time
increasing employee morale and job
satisfaction.
• To maximize plant and equipment
effectiveness to achieve optimum life cycle
cost of equipment.
Goal of TPM

Evolution of TPM
• Dr.W.Edward Deming – Japanese Industry
• Nippon Denso of Toyoto groups – Quality
circle, Involving employees participation

Implementation of TPM
Stage I
Initialization
(Preparatory)
Stage II
Introduction on TPM
(Take off phase)
Stage III
Implementation
Stage IV
Institutionalization
(Stabilization Phase)

Stage I Initialization
(Preparatory Phase)
• Discussions with workers union
representatives
• Establish basic TPM policies and goals –
Analyze the existing condition
• Preparation and formulation of master plan

Stage II Introduction on TPM
(Take off phase)
• Formal presentation by top executive with
all employees attending.
• To get the full support of all employees.
• Also invite our external customers,
suppliers, contractors and affiliated
companies to get their supports.

Stage III Implementation
• 5’S Principle
• Autonomous Maintenance (JISHU HOZEN)
• KAIZEN
• Planned Maintenance
• Quality Maintenance
• Training
• Office TPM
• Safety, Health and Environment

Stage IV Institutionalization
(Stabilization Phase)
• Once TPM has been implemented, it should
be properly monitored and evaluated and
some reward system can be introduced for
further encouragement.
• The Japanese institute for productive
maintenance runs an annual PM Excellence
Award.

TPM Objectives
Objectives
of TPM
Zero Defect
Zero
breakdown
Involvement
of people
from various
levels
Reliable
maintenance
policy

Benefits of TPM
• Enhanced/ improved productivity and
overall efficiency
• Reduction of manufacturing cost.
• Customer satisfaction by delivering right
quantity at right time with expected quality.
• Minimization of accidents.
• High confidence level among employees.

Category TQM TPM
Objective To have quality
output
To have reliable
equipment
Means of achieving Through
systematized
management
Through active
participation of
employees
Target Minimized defective
through planned
preventive
maintenance
Elimination losses
and wastes

Pillar -1: 5S Principle

Pillar -2: Jishu Hozen(JH)
• Training employees
• Initial cleanup of machines
• Taking counter measures
• Fixing tentative JH standards
• General Inspection
• Autonomous inspection
• Standardization
• Autonomous management

Pillar -3: KAIZEN

Elements of KAIZEN

Motorola’s steps for continuous
improvement

Major losses in an organization
• Equipment efficiency based losses
1. Failure/Breakdown losses
2. Setup/adjustment losses
3. Minor stoppage/ idling loss
4. Speed loss-Operating at low speeds
5. Defect/Rework loss
6. Scheduled downtime loss
• Human work efficiency based losses
1. Management loss
2. Operating motion loss
3. Line organization loss
4. Measurement and Adjustment loss

• Effective use of Production Resources
1. Energy loss
2. Die, Jig and Tool breakage loss
3. Yield loss

Pillar -4: Planned Maintenance(PM)
1. Preventive Maintenance
2. Corrective Maintenance
3. Predictive Maintenance
4. Condition Based Maintenance
5. Reliability Centered Maintenance

Pillar -5: Quality Maintenance(QM)
1. Its aimed towards customer delight by
getting them the highest quality through
defect free manufacturing.
2. Its focused on eliminating non
conformances in a systematic manner.
3. Understanding of what parts of the
equipment affect product quality and begin
to move potential quality
concerns.

Pillar -6: Training
 Its aimed to have multi skilled employees
whose morale is high and who are eager to
work and perform all the required
functions independently and effectively.
 Its not sufficient to know only “Know-How”
but they should also learn “Know-Why”.

Target:
 Achieve and sustain downtime at zero on
critical machines.
 Achieve and sustain zero losses due to lack
of knowledge/skills/techniques.
 Aim for 100% participation in suggestion
scheme.

Pillar -7: Office TPM
• To improve productivity, efficiency in the
administrative functions and identify-
eliminate losses.
• Analyzing processes and procedures
towards increased office automation.

Office TPM Major Losses
• Processing loss.
• Cost loss (Accounts, Marketing, Sales)
• Communication loss
• Idle loss
• Set-up loss
• Accuracy loss
• Office equipment breakdown
• Communication channel breakdown(Telephone,
Fax Lines)
• Non availability of correct on line stock status
• Customer complaints due to logistics

Benefits of Office TPM
• Involvement of all people in support functions for
focusing on better plant performance.
• Better utilized work area
• Reduce repetitive work
• Reduced inventory levels in all parts of the supply
chain.
• Reduced administrative cost
• Reduction in number of files
• Reduced manpower
• Clean and pleasant work environment

Pillar -8: Safety, Health and Environment
• Zero accident
• Zero health damage
• Zero fires

Maintenance Scheduling
• Maintenance scheduling is a joint maintenance
operations activity in which maintenance agrees to
make the resources available at a specific time
when the unit can also be made available by
operations.

Stakeholders
of
maintenance
scheduling
Planner
Scheduler
Maintenance
Supervisors
Craftsman
Store’s In
charge
Operation
Superinten
dent
Operator

1. Planner
He/She should ensure that the work is properly
planned with respect to customer requirements,
Stores material, directly purchased materials, etc.
also work to be carried out with line of safety
requirements should be described.

2. Scheduler
He/She should ensure that,
• Trades are available to conduct the work
during the schedule duration.
• Materials and service availability.
• Communicating the details of the above to
person involved in maintenance and
operation.

3. Maintenance Supervisor
He/She will be responsible for the day to day
activities comprised in weekly schedule and
also determine the business availability.
4. Craftman:
He/She execute the assigned task and keep
informing the maintenance team, the outcome
as well as any practical difficulty in their part,
for any further analysis.

5. Storeroom personnel:
They maintain the records of receipt of goods
and notify if any damage exists.
6. Operation Superintendent:
He must be kept informed in advance about
the equipment condition.
7. Operator:
He is the person responsible for securing the
equipment and report back to maintenance
personnel if any deviation is observed.

Maintenance
Scheduling
Principles
Schedules are
important job
priorities are
important
Schedule from
forecast of
highest skills
available
Schedule for
every
workhour
available
Crew leader
handles current
day’s work
(Daily
schedules)
Measures
performance
by analysis of
schedule
compliance
Plans with
lowest
required
skill level

Repair
• To restore to a good or sound condition
after decay or damage.
• Inspection(I)
• Minor Repair (R1)
• Major Repair(R2)
• Overhauling(O)

Repair Cycle
• The repeated performance of all/some of
the above mentioned activities in sequence
between successive overhauling is termed
as Repair Cycle.

O
I
R1
R2
I
R1
I
R2

Lubrication
• To reduce wear and heat between contacting
surfaces in relative motion.
• Coefficient of friction could be reduced and inturn
heat and wear of the surfaces.
• Lubrication also aids to
1. Reduce oxidation and rust formation
2. Transmit mechanical power in hydro fluid
power systems.
3. Seal against dust, dirt and water.

Lubricants
• Any materials used to reduce friction between
wearing surfaces with high coefficient of
friction, by establishing low viscous film are
called lubricants.
Methods of Lubrication:
• Hydrostatic Lubrication
• Hydrodynamic/ Fluid film Lubrication
• Boundary Lubrication
• Elasto hydrodynamic Lubrication (EHD)
• Extreme pressure Lubrication (EPL)

Method of lubrication is based on:
Mean fluid film thickness
R =
Surface Roughness
Where,
R is less than or equal to 1 for Boundary/Hydrostatic
Lubrication
R is in between 5 and less than or equal to 100 for
mixed lubrication or EHD/EPL
R is between 1 and 5 for fluid film lubrication

1. Hydrostatic Lubrication
A thin film of lubrication is created between
the journal and the bearing by supplying
lubricant under pressure with an external
source like pump.

2. Hydrodynamic/ Fluid film Lubrication
In heavy loaded bearing such a thrust
bearings and horizontal journal bearings
apart from viscosity of fluid, higher fluid
pressure is also required to support the
load.
In hydrodynamic lubrication a fluid wedge is
formed by the relative surface motion of the
journals over their bearing surfaces.

Ex: Cylindrical Journal Bearing & Connecting
rods

3. Boundary Lubrication
When a full fluid film is not developed
between rubbing surfaces, the thickness of
film may be reduced so that dry contact is
formed at high points of mating surfaces.
Ex: Gear Teeth

4. Elasto hydrodynamic Lubrication (EHD)
• The lubrication principle is applicable to
rolling bodies such as ball or roller bearings.
• Elastic deformation of the contacting bodies
under load and hydrodynamic effects
forcing the lubricant to separate the
contacting surfaces while the pressure of
the load is deforming them.
• Ex: Ball bearings

5. Extreme pressure Lubrication (EPL)
In heavy loading applications, oil temperature
raises beyond the anti wear protection.
Under this situation lubricants containing
additives that protect against extreme
pressure (EP) lubricants are used.
EPL can be achieved by chemical compounds
of boron, phosphorus, sulphur, chloride or
combination of these.