kuliah maintenance pendahuluan minggu1 semester3 2013

8/13/2019 Kuliah Maintenance Pendahuluan Minggu1 Semester3 2013

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KULIAH PEMELIHARAAN PERKAKASPRESISI

INTRODUCTION TOMAINTENANCE


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Operators less able to do repairs themselvesMachine and product failure can have effect on companys operation and

profitability

Idle workers, facilityLosses due to breakdown

INTRODUCTION


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Failure inability to produce work in appropriatemanner

Equipment / machine failure on production floor worn out bearing, pump, pressure leaks, broken shaft,

overheated machine etc.Equipment failure in office failure of power supply,air-conditioned system, computer network, photocopy

machine Vehicle failure brake, transmission, engine, coolingsystem

FAILURE


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HospitalRestaurants

Transport companiesBanks

Hotels and resortsShopping malls / retail

Gas station

MAINTENANCE IN SERVICEINDUSTRY


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Electronic Automotive

PetrochemicalsRefineryFurnitureCeramics

Food and beverages

MAINTENANCE IN MANUFACTURING COMPANIES


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All actions necessary for retaining an item, or restoring to it, a serviceablecondition, include servicing, repair, modification, overhaul, inspection and

condition verification

Increase availability of a systemKeep systems equipment in working order

MAINTENANCE


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Why do we need maintenance? What are the costs of doing maintenance?

What are the costs of not doing maintenance?

What are the benefits of maintenance?How can maintenance increase profitability of company?

QUESTION?


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Attempt to maximize performance of production equipment efficiently andregularly

Prevent breakdown or failures

Minimize production loss from failuresIncrease reliability of the operating systems

PURPOSE OF MAINTENANCE


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To achieve product quality and customer satisfactionthrough adjusted and serviced equipment

Maximize useful life of equipmentKeep equipment safe and prevent safety hazardsMinimize frequency and severity of interruptions

Maximize production capacity through high utilizationof facility

PRINCIPLE OBJECTIVES IN MAINTENANCE


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Lack of management attention to maintenanceLittle participation by accounting in analyzing and

reporting costsDifficulties in applying quantitative analysis

Difficulties in obtaining time and cost estimates for

maintenance worksDifficulties in measuring performance

PROBLEMS IN MAINTENANCE


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Cost to replace or repairLosses of outputDelayed shipmentScrap and rework

MAINTENANCE COSTS


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Maintenance may be classified into four categories:(some authors prefer three categories- scheduled and preventive

maintenances are merged)

Corrective or Breakdown maintenanceScheduled maintenance

Preventive maintenancePredictive (Condition-based) maintenance

TYPES OF

MAINTENANCE


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Corrective or Breakdown maintenance implies thatrepairs are made after the equipment is failed and can

not perform its normal function anymore

Quite justified in small factories where:

Down times are non-critical and repair costs are less than othertype of maintenance

Financial justification for scheduling are not felt

CORRECTIVE ORBREAKDOWN

MAINTENANCE


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Breakdown generally occurs inappropriate times leading topoor and hurried maintenance

Excessive delay in production & reduces output

Faster plant deteriorationIncreases chances of accidents and less safety for both workers and machinesMore spoilt materials

Direct loss of profitCan not be employed for equipments regulated by statutory

provisions e.g. cranes, lift and hoists etc

DISADVANTAGES OFCORRECTIVE

MAINTENANCE


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Scheduled maintenance is a stitch-in-time procedure andincorporates

inspection

lubricationrepair and overhaul of equipments

If neglected can result in breakdownGenerally followed for:

overhauling of machines

changing of heavy equipment oils

cleaning of water and other tanks etc.

SCHEDULED

MAINTENANCE


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Principle Prevention is better than cure Procedure - Stitch-in-time

Itlocates weak spots of machinery and equipments

provides them periodic/scheduled inspections and minor

repairs to reduce the danger of unanticipated breakdowns

PREVENTIVEMAINTENANCE

(PM)


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CANDIDATES FOR PREVENTIVE MAINTENANCE

Mean Time Between Failure (MTBF)

Frequency of FailureGood candidateshave more normal

distribution withlow variability


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Advantages:Reduces break down and thereby down time

Lass odd-time repair and reduces over time of crews

Greater safety of workers

Lower maintenance and repair costs

Less stand-by equipments and spare parts

Better product quality and fewer reworks and scrapsIncreases plant life

Increases chances to get production incentive bonus

ADVANTAGES OF

PM


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In predictive maintenance, machinery conditions areperiodically monitored and this enables the

maintenance crews to take timely actions, such asmachine adjustment, repair or overhaul

It makes use of human sense and other sensitive

instruments, such asaudio gauge, vibration analyzer, amplitude meter, pressure,

temperature and resistance strain gauges etc.

PREDICTIVE(CONDITION-

BASED)MAINTENANCE


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Unusual sounds coming out of a rotating equipment predicts a trouble An excessively hot electric cable predicts a trouble

Simple hand touch can point out many unusual equipment conditions andthus predicts a trouble

PREDICTIVEMAINTENANCE

(CONTD.)


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MAINTENANCE COSTS

MaintenanceCommitment

Cost

Breakdown Cost


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MAINTENANCE COSTS


Cost

PM Cost

Breakdown Cost


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MAINTENANCE COSTS


Cost

PM Cost

Breakdown Cost

Total Maintenance Cost


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MAINTENANCE COSTS


Cost

PM Cost

Total Maintenance Cost

Breakdown Cost

Optimal


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Problem: A factory has 200 machines and the maintenance engineer

supervises the repair crews who repair malfunctioning machines. The maintenance policy is to repair the broken down machineand bring back in production within 2 hours on the average. Ifaverage breakdown rate is 3.5 machines/hour and each repair

crew can repair 0.25 machine per hour on the average. How manyrepair crews are required ?

DETERMINING THESIZE OF REPAIR

CREWS


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The formula for average repair rate ( ) is1

ts = ---------- or = + 1/ ts -

Where = repair rate = arrival rate of malfunctioning machines

ts = average time arrivals in the system

Required average repair rate = 3.5 + 1 / 2 = 4 machines / hour

No. of Crews = machines/hour a crew can repair= 4 0.25 = 16 repair crews required

SOLUTION


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Thanks...

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kuliah maintenance pendahuluan minggu1 semester3 2013

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