Intro to Maintenance

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Maintenance

Maintenance management is the routineand recurring process of keeping a

particular machine or asset in its normaloperating condition so that it can deliver itsexpected performance or service withoutcausing any loss of time on account of

accidental damage or breakdown. Increase availability of a system Keep systems equipment in working order


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Question

!hy do we need maintenance !hat are the costs of doing

maintenance !hat are the costs of not doing

maintenance

!hat are the benefits of maintenance "ow can maintenance increase

profitability of company


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#urpose of Maintenance

$ttempt to maximi%e performance of

production equipment efficiently and

regularly #revent breakdown or failures

Minimi%e production loss from failures

Increase reliability of the operating

systems


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#rinciple &b'ectives in

Maintenance

(o achieve product quality and customersatisfaction through ad'usted and servicedequipment

Maximi%e useful life of equipment Keep equipment safe and prevent safety

ha%ards

Minimi%e frequency and severity of interruptions Maximi%e production capacity ) through high

utili%ation of facility


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#roblems in Maintenance

*ack of management attention to

maintenance

*ittle participation by accounting in analy%ingand reporting costs

+ifficulties in applying quantitative analysis

+ifficulties in obtaining time and costestimates for maintenance works

+ifficulties in measuring performance


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#roblems ,xist +ue (o-

ailure to develop written ob'ectives andpolicy

Inadequate budgetary control Inadequate control procedures for work order/

service requests etc. Infrequent use of standards

(o control maintenance work$bsence of cost reports to aid maintenance

planning and control system


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Maintenance &b'ectives

Must be consistent with the goals of

production 0cost/ quality/ delivery/

safety1 Must be comprehensive and include

specific responsibilities


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Maintenance 2osts

2ost to replace or repair

*osses of output

+elayed shipment

3crap and rework


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Types of Maintenance

Maintenance may be classified into four categories-

0some authors prefer three categories4 scheduled

and preventive maintenances are merged1

2orrective or 5reakdown maintenance

3cheduled maintenance

#reventive maintenance #redictive 02ondition4based1 maintenance


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Corrective or Breakdown

Maintenance

2orrective or 5reakdown maintenance

implies that repairs are made after the

equipment is failed and can not perform itsnormal function anymore

Quite 'ustified in small factories where-

) +own times are non4critical and repair costs are

less than other type of maintenance

) inancial 'ustification for scheduling are not felt


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Disadvantages of Corrective

Maintenance 5reakdown generally occurs inappropriate times

leading to poor and hurried maintenance

,xcessive delay in production 6 reduces output

aster plant deterioration Increases chances of accidents and less safety for

both workers and machines

More spoilt materials

+irect loss of profit 2an not be employed for equipments regulated by

statutory provisions e.g. cranes/ lift and hoists etc


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Scheduled Maintenance

3cheduled maintenance is a stitch4in4time

procedure and incorporates

) inspection

) lubrication

) repair and overhaul of equipments

If neglected can result in breakdown

7enerally followed for-

) overhauling of machines) changing of heavy equipment oils

) cleaning of water and other tanks etc.


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Preventive Maintenance (PM)

#rinciple ) 8#revention is better than cure9

#rocedure 4 3titch4in4time

It)locates weak spots of machinery and equipments

)provides them periodic:scheduled inspections and

minor repairs to reduce the danger of

unanticipated breakdowns


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2andidates for #reventive

Maintenance

Mean Time Between ailure (MTB)Mean Time Between ailure (MTB)

re!uency of ailurere!uency of ailure"ood candidates"ood candidates

have more normalhave more normal

distri#ution withdistri#ution withlow varia#ilitylow varia#ility


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$dvantages of PM

$dvantages-);educes break down and thereby down time

)*ass odd4time repair and reduces over time of

crews)7reater safety of workers

)*ower maintenance and repair costs

)*ess stand4by equipments and spare parts

)5etter product quality and fewer reworks andscraps

)Increases plant life

)Increases chances to get production incentivebonus


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Predictive (Condition%#ased)

Maintenance

In predictive maintenance/ machinery conditionsare periodically monitored and this enables themaintenance crews to take timely actions/such as machine ad'ustment/ repair or overhaul

It makes use of human sense and othersensitive instruments/ such as)audio gauge/ vibration analy%er/ amplitude meter/

pressure/ temperature and resistance strain gaugesetc.


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Predictive Maintenance (Contd&)


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Maintenance 2osts

MaintenanceMaintenance

CommitmentCommitment

CostCost

Breakdown CostBreakdown Cost


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Maintenance 2osts



CostCost

PM CostPM Cost



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Maintenance 2osts



CostCost

PM CostPM Cost


Total Maintenance CostTotal Maintenance Cost


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Maintenance 2osts



CostCost

PM CostPM Cost

Total Maintenance CostTotal Maintenance Cost


'ptimal'ptimal


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Determining the Sie of epair Crews

#roblem-

$ factory has =>> machines and the maintenance

engineer supervises the repair crews who repair

malfunctioning machines. (he maintenance policy is

to repair the broken down machine and bring back in

production within = hours on the average. If average

breakdown rate is ?.@ machines:hour and each repair

crew can repair >.=@ machine per hour on theaverage. "ow many repair crews are required


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3olution

(he formula for average repair rate 01 is

A

ts B 4444444444 or B C A: ts

4

!here B repair rate

B arrival rate of malfunctioning machines

ts B average time arrivals in the system

;equired average repair rateB ?.@ C A : = B D machines : hour

Eo. of 2rews B machines:hour a crew can repair

B D >.=@ B AF repair crews required

Documents

Intro to Maintenance