6. Equipment Efficiency Availability

8/22/2019 6. Equipment Efficiency Availability

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Equipment Efficiency:Availability, Performance

and Maintenance

Operations Analysis and Improvement

2010 Fall

Dr. Tai-Yue Wang

Industrial and Information Management Department

National Cheng Kung University


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Dr. Tai-Yue Wang IIM Dept. NCKU 2/80

Presentation The role of maintenance is to insure the

survivability and proper functioning of all

company hardware. Most maintenance departments are considered a

necessary evil.

Investments required to improve production processesusually take on a low priority.


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Presentation Maintenance evolution, as well as maintenance

technique evolution, has developed in parallel for

many companies. Remediate hardware failures.

Prevent future problems with the equipment.

Incorporate basic maintenance tasks into their dailyproduction routine.

Predicting equipment breakdowns.


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Introduction

Maintenances primary objective is to

maintain, at a high operative level, theproductive resources in order to assure their

service at an expected cost.

Maintenance is the machines medicine.

Determine the right moment to replace the

equipment.

It may be better to simply unplug it.


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Introduction Elements that need maintenance.

Machines and tools.

Facilities (compressed air,heating,)

Buildings (walls, illumination,)

Information and transportationsystems.

20

1612119

7

14 5

4

8

15131019

18

17

6

1

2 3

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Workforceoptimization

VisualControl

LevelingProduction

Kanban

Multi-functionalworkers

SMED


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Introduction Some companies subcontract

maintenance.

Is contemplated in both theJust-in-time and the 20 keys

(key number 9) for lean.

Improves the availability andperformance rates of the

equipment.

20

1612119

7

14 5

4

8

15131019

18

17

6

1

2 3

Thinkingrevolution

The 5S

Standardoperations

One-Pieceflow

Poka-Yoke Jidoka

TPM

JUST IN TIME

Workforceoptimization

VisualControl

LevelingProduction

Kanban

Multi-functionalworkers

SMED


7/80Dr. Tai-Yue Wang IIM Dept. NCKU 7/80

Types of maintenance Corrective -> All industrial equipment is

exposed to transitory (wear) or definitive

breakdowns (catastrophic failure). Affecting its functionality and performance.

Can represent high costs for enterprises.

Preventive -> The maintenance missioncannot only be repairing the breakdowns.

They should be able to get ahead of the

breakdowns.


8/80Dr. Tai-Yue Wang IIM Dept. NCKU 8/80

Corrective maintenance Also called breakdown maintenance.

Up to the 1950s it was virtually the only

maintenance. Machine stoppages hardly affected productive time.

Repairs were carried out in an effective way.

Equipmentperformance Substitution

Repair

Time until failure

Repair time

Time


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Types of corrective maintenance Urgent repairs.

Reestablishing the equipment into service.

Repair is carried out is temperally.

The remainder of the tasks will/can be

scheduled for a future time.


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Types of corrective maintenance Scheduled corrective.

Appears as a result of urgent repairs.

Determine an appropriate time to repair the

machine completely.

After repairing the damaged component

As good as new.

At least as it was before.


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Repair problems

Repair tasks are performed quickly and

under pressure, which can cause future

problems.

Repair time can be very high because

replacement part(s) may have to be

ordered from a supplier.


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Repair problems

Accidents can take place because of poor

maintenance safety measures.

Corrective maintenance policy implies higher

labor costs.

This policy can be justified in some cases.

Equipment with a frequent replacement policy.

Like personal office computers.

When breakdown costs are small.

Light bulbs fail.


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Types of preventive

maintenance

The preventive maintenance has two variants.

Systematic preventive maintenance.

Conditional preventive maintenance or predictivemaintenance.


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Systematic preventive

maintenance

1960s -> the General

Electric Corporation

systematized a newtype of maintenance

called planned

maintenance.Equipment

performanceSubstitution

Theoretical time until failure

Intervention duration

Time


Repair

Time until failure

Repair time

Time


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maintenance

Planned maintenance arrived to

Japan.

The bases of this systematicpreventive maintenance process

were established.

Systematic substitution of some

machine components.

Equipmentperformance

Substitution



Time


Repair

Time until failure

Repair time

Time


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maintenance

Applied to general wear or use

components.

Know with precision thecomponents performance

characteristics.


Substitution



Time


Repair

Time until failure

Repair time

Time


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maintenance

Replacement policy might call for a

component to be replaced every week or

in other ways such as, every 300

working hours or every 1000 parts

produced. Equipmentperformance

Substitution



Time


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Conditional preventive

maintenance

Also called predictive

maintenance.

Systematic preventivemaintenance can

become very

expensive.Equipmentperformance Substitution



Time

Inspections


Substitution



Time


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maintenance


maintenance is used to change

components depending ontheir current state.

The useful life for costly

components can be extended.

This type of maintenance best

fits components where

performance can be

monitored.


Substitution



Time

Inspections


Substitution



Time


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maintenance

ISO 14000 (environmental

norm) requires that industry

avoid systematic preventivemaintenance when working

with environmentally harmful

products.Equipment

performanceSubstitution



Time

Inspections


Substitution



Time


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maintenance

Predictive maintenance.

Look for correlations between

multiple parameters and thedegradation of a component.

Temperature (thermocouples),

Noises (phonometer).

Cracks (X-rays machine).

Pressure losses (manometer).

QS9000 recommends

predictive maintenance.


Substitution



Time

Inspections


Substitution



Time


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Maintenance program

implementation

Almost all machines follow a similar

lifecycle.

Hidden small defects.

Difficult to detect and to observe -> It does not

interfere with functionality.

Increase of friction in an axle.

Apparent small defects.

Are more noticeable -> They are normally not

repaired.

Small vibrations on a machine.


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Maintenance program

implementation

Execution under expectations.

The defects affect the equipment productivity.

the standards of quality will be violated.


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Maintenance program

implementation

Almost all machines follow a similar lifecycle.

Intermittent stops.

The machine intermittently produces defect parts.

Small repairs are performed.

Stops and breakdowns.

Breakdowns are frequent.

Production equipment may not be as new as we

would like them to be.

Stops and breakdown stage.


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Maintenance program

implementation

Production equipment typically becomes more

sophisticated/complex.

More expensive every year.

It has greater economic impact.

Repairs should be done at a faster rate.

Working shifts can also represent an obstacle formaintenance interventions.

Limits possible maintenance tasks and scheduling.


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Maintenance program

implementation

The objective of maintenance is to efficiently

oversee equipment throughout the equipment life

cycle.

Cover the entire lifecycle

Implementing an effective corrective maintenance.

Preventive maintenance tasks. Implementing predictive maintenance strategies.


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Getting started

Become familiar with the resources that will

require maintenance.

Each maintained resource should be coded (resourceid#).

Code the types of breakdowns and maintenance

tasks. In a historical data study -> Group failure causes.


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Getting started

Maintenance should have the following two

documents.

Facility Inventory.

Lists all equipments and their principle characteristics.

Code, record number, equipment type,

Equipment History Files.

Data given by the equipment manufacturer.

Information about the location in the plant.

Types of spare parts needed.


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Corrective maintenance

implementation

Organize, in an effective way, the corrective

maintenance procedures and actions.

Breakdown occurs -> Fill out a breakdownwork order.

If the worker can solve it -> fill a report.

If not -> the work order will be sent to the

maintenance department.

Work request order will be issued.

Maintenance workers will either repair the machine

immediately or will schedule the repair.

The repair can be provisional or definitive.


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Scheduled corrective

maintenance

Variability in the corrective maintenance tasks

duration can be problematic.

Corrective orders and flow diagrams for repetitiverepairs must be developed.

Materials and spare parts that should be utilized.

Maintenance workers tasks do not end with theequipment repair.

They should gather all the breakdown information.

Describe the process that was performed.


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maintenance

Each machine should have its own file with

breakdown records.

Analyze breakdown causes.

Anticipate future problems.

This file must be upgraded with each maintenance

intervention.


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maintenance

Corrective maintenance tasks do not only consist

on changing the broken or malfunctioning

components. Study the causes and the frequency of the

breakdowns.


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Preventive maintenance

implementation

Avoid a breakdown of any resource, while

keeping maintenance cost as low as possible.

Two types of actions.

Inspections.

Observe and detect possible anomalies.

Frequent checkups that follow a specific inspection plan.

Revisions.

Scheduled equipment stops.

Systematic substitution of several machine components.

Carried out during the weekend.


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implementation

Preventive maintenance tasks scheduling is

mandatory in the ISO norms.


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implementation

These tasks can be planned daily, weekly,

monthly or even annually.

Scheduled at times when they do not affect the

factorys production plan.

Daily working problems force us to continuously

reschedule these tasks.


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implementation

Equipment preventive maintenance tasks are

also called PM orders.

Each PM order should be based on a study of the

equipment breakdown causes.

FMEA tool described at the tools section.


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Autonomous

maintenance

PM orders carried out by the production

workers. Known as user maintenance orders.

They should be simple and graphically

represented. Many inspection tasks should be carried out every

day.


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Autonomous maintenance

Significant amount of notices that could be

easily handled by the production worker.

It takes more time to fill out the request order than tofix the problem


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Autonomous maintenance includes these small

tasks and three daily preventive measures.

Cleaning, lubricating and checking.


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Autonomous maintenance. Safety

Safety is one of the most important

restrictions.

Autonomous tasks apply only for simple repairoperations.

Repair or maintenance should never be

performed if the knowledge required to fixthe machine is high.


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Autonomous maintenance. Safety

It can be very challenging to convince

production workers about the importance of

maintenance tasks. They do not consider their responsibility.


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Autonomous maintenance implementation

process has a specific methodology.

Initial cleaning1

Countermeasures to Sources of Contamination2

Cleaning and Lubricating Standards3

Overall inspections4

Autonomous Maintenance Standards5

Process Quality Assurance6

Autonomous Supervision7


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TPM - Total Productive

Maintenance

In the 1970s, Nakajima developed in Japan

TPM.

New maintenance management philosophy.

English translation was not published until

1988.

JIPMJapanese Institute of Plants Maintenance.

Grants the PM prize to the TPM top excellent

companies.

60% of the winning companies during the first 17 years are now

part of the Toyota Group or suppliers of this Group.


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TPM - Total Productive

Maintenance

Nakajima combined preventive

maintenance theories with the total

quality concept. Nakajima developed the Overall Equipment

Efficiency ratio.


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TPM keys

Maximize the Overall Equipment Efficiency.

Eliminating the six big losses.

Autonomous maintenance implementation.

In order to terminate the I operate, you repair

mind set.

Preventive engineering. Improving the equipments maintainability.


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TPM keys

Training workers for maintenance

improvements.

Propose methods for increasing the equipmentavailability.

Initial equipment management.

The objective of the TPM -> ZeroBreakdowns.

Utilize tools such as the P-M analysis -> Explained

in tools section.

li bili d


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RCM - Reliability Centered

Maintenance

RCM was created in the United States in the

1960s, to optimize the reliability of

aeronautical equipment. RCM was not utilized in nuclear power stations

until the 1980s.

Recently has been implemented in the industrialworld.

C li bili C d


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RCM - Reliability Centered

Maintenance

Needs a complete maintenance and

breakdown record for each item of

equipment. RCM objective is to determine the maintenance

tasks that are more effective for the critical

components.

FMEA, reliability analysis, statistical techniques.

It is necessary to have a preventive maintenance

program implemented and running properly.


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FMEA for equipment

All defects have a root cause, and to eliminate

future defects an action must be carried out.

Defect -> Gap between two elements

Cause -> Lack of lubrication or a loose fastener.

Action -> Grease or tighten the lose element.


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FMEA for equipment

To determine a good preventive maintenance

plan, all the possible breakdowns, their causes

and their corrective actions must be analyzed. The main tool to carry out this type of analysis is the

FMEA for equipment (Failure Mode and Effects

Analysis).

Is a guide to analyze, in an organized manner, causes of

possible equipment breakdowns.

A group of workers is gathered to study the problems and

failures


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EQUIPMENT CARRIED OUT BY DATE

PAGE OF

Equipment

functionsFailure modes Fa iu lre e fects Failure causes

Actual

controls

Recommended

actions Responsible

FMEA for equipment

EQUIPMENT CARRIED OUT BY DATEPAGE OF

Equipmentfunctions

Fai lu re m odes Fa iu lr e e fe c ts Fa il ur e c au se sActualcontrols

Recommendedactions Responsible


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FMEA for

equipment

Equipment functions.

The functions that the equipment carries out.

Provides compressed air during specific conditions.

Failure modes.

All the possible ways that the equipment can be

forced to stop. Breaks, blockage, leaks, etc.

EQUIPMENT CARRIED OUT BY DATEPAGE OF

Equipmentfunctions




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FMEA for

equipment

Failure effects.

All possible consequences of each failure are

analyzed in detail. Severity (S).

1 being not very serious.

4 very serious or 10.

fEQUIPMENT CARRIED OUT BY DATE

PAGE OF

Equipmentfunctions




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FMEA for

equipment

Failure causes.

The origin of the failure is analyzed.

Identify the anomaly that can lead to the failure.

Probability (P).

1 not very frequent.

4 very frequent or 10.

A fEQUIPMENT CARRIED OUT BY DATE

PAGE OF

Equipmentfunctions




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FMEA for

equipment

Actual controls.

If, at the present time, some kind of control is carried

out.

Detection (D)

1 if the control does not always detect the cause

4 if it always detects or 10.


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FMEA for equipment

After the first part of the FMEA table has

been completed, the Risk Priority Number

(RPN) is calculated. The product of the three quantified variables (S,

P and D).

Ranking failures by RPN. Analyze the causes that do not represent any threat.

Special attention must be paid to those effects that

have been considered critical.


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FMEA for equipment

The chosen plan of action and the employee

responsible for carrying out this plan are

registered in the same table utilized in theFMEA.

After a FMEA application arises, the necessity

of developing a preventive maintenance plan isrecommended.

FMEA f

EquipmentperformanceSubstitution


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FMEA for

equipment

Preventive maintenance intervention

periods (T).

Know the component damage/wear behaviorcurve.

Breakdowns and the time when the breakdowns

occurred -> Mean Time Between Failures (MTBF).

T is based on the corrective percentage that the

company would like to support (K).

MTBF

MTTR

Time

T = KMTBF


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Reliability

Reliability is defined as the probability that an

equipment will work satisfactorily, during a

certain period of time under some specificworking conditions.

Reliability is a probability.

Relative frequency of breakdowns.


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Reliability

All production equipment should work

satisfactorily.

Failure can be triggered by an abrupt change in thecomponent characteristic or by progressive damage.

Work satisfactorily for a specific period of time.

Maintain quality standards during a reasonableperiod of time.

RELIABILITY = QUALITY + TIME


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Reliability

The component life or equipment life

duration depends on working conditions.

Environmental (temperature or humidity).

Operational (continuous starts and stops,

electrical strain).


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Reliability

The system state depends on the primary

group of elements that makes it work

properly. Each element has a random lifetime.

Estimate the lifetime of the components.

Reliability -> MBTF (Mean Time BetweenFailure)

failuresofNumber

timeOperatingMTBF

failuresofNumber

timetotalFailuresMTTR


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Reliability and Maintainability

Maintainability -> probability that it must be

repaired in a predetermined time following a

specific repair procedure.

failuresofNumber

tit t lF il


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Reliability and Maintainability

Maintainability depends on different factors.

Machine factors.

Accessibility or interchangeability among components.

Organizational factors.

Maintenance staff knowledge, documentation availability,

Operative factors. Ability of the manpower.

Is quantified through the MTTR (Mean Time To

Recovery).

failuresofNumber

timetotalFailuresMTTR

R li bilit d St ti ti l


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Reliability and Statistical

availability

Average between the middle time used in the

equipment and the required production time

If the different times between breakdowns aswell as each repair duration time are

graphically represented this process.

t

TBF1 TBF2 TBF3

TR1 TR2 TR3

MTTRMTBF

MTBFtyavailabililstatistica


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Reliability - the Bathtub curve

Is a graphic representation of the failure rate

l(t).

Probability that an element fails depending on itslife use stage or status.

ZONE I. Infant period.

ZONE II. Useful period.

ZONE III. Waste period.

time

l(t)

ZONEI

ZONEII

ZONEIII

R li bilit Th b tht b


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ReliabilityThe bathtub curve:

Zone I

Equipment set up and debug process.

Goes downhill because, as time moves

forward, the probability of acomponent failure decreases.

The problems in this area can be

avoided by making intensive tests orby exchanging troublemaker elements

at an early stage adjustment period.

l(t)

ZONEI



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ReliabilityThe bathtub

curve: Zone II

Zone II.

Failures randomly appear.

Electronic systems. The curve formed is virtually

horizontal.

In mechanical systems.

The curve normally has a slightlypositive slope.

ti

ZONEIII

ZONEII



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ReliabilityThe bathtub curve:

Zone III

Zone III.

Failures come from components farmore quickly.

Critical components replacement is

strongly recommended.

ti

ZONEIII

ZONEII

Defects

sporadic losses


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P-M Analysis

Defects reasons.

Sporadic() losses.

Chronic() losses.

Sporadic losses can be corrected using tools

already studied.

Time

zero losses

chronic losses

Defects

sporadic losses


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P-M Analysis

The P-M analysis is responsible for eliminating

chronic losses.

Considered natural according to their root sources. P - > Phenomenon.

M - > Mechanism.

Time

zero losses

chronic losses

Defects

sporadic losses


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P-M Analysis

Reliability that has been studied has two aspects

to consider.

Intrinsic reliability. Due to the design and production of the component.

Operative reliability.

Due to the component use and the maintenance process.

Time

zero losses

chronic losses

Defects

sporadic losses


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P-M Analysis

P-M analysis should be applied after

conventional improvement.

Six sigma is also suitable to carry out this typeof study.

Time

zero losses

chronic losses


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Maintenance management

A maintenance department should properly

manage and control their costs.

Unlimited number of indicators that can be usedfor maintenance department performance.

Manpower performance, hours dedicated to urgent

work, repair cost, availability,...


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Maintenance management

Maintenance management is a difficult task

because it frequently does not have

managements support. As long as the maintenance department does not

exceed its assigned budget, no one pays much

attention to the maintenance department activities or

expenses.


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Maintenance costs

Using economic terms, maintenance

management helps to control deviations in the

firms budget and also to determine investmentneeds to reduce the costs.


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Maintenance costs

There are two alternatives or opposing costs.

Non-maintenance costs.

Opportunity costs, quality costs, production manpowercost, etc.

Maintenance costs.

Breakdown prevention costs, anomalies detection cost,

inspection resources costs, etc.

MaintenanceCost

Total costs


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Maintenance

costs

(1) -> Maintenance investment increases the

equipment availability and at the same time

(2) -> An increase of the availability,

supposes large investments.

Availability

Non-maintenancecosts

Maintenance costs

0 % 100 %

21


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Summary

This chapter has provided an overview of

maintenance activities, a critical aspect of Lean

Manufacturing. Maintenance planning andmonitoring activities are critical factors for Lean

Enterprise efficiency.


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Summary

Unfortunately, maintenance is normally

perceived as a necessary evil, and is not always

seen as a critical engineering activity. Thischapter has outlined some of the maintenance

policies and procedures that can be used to

obtain the goal for any production system:operate as efficient as possible at the lowest cost.

6. Equipment Efficiency Availability

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