*MINGGU VIII

LABORATORIUM SISTEM MANUFAKTURTEKNIK INDUSTRI ITS SURABAYA2010

Maintenance Strategy, CM v/s PM Corrective maintenance (CM)The actions carried out (because of failure) to repair component, equipment, or a system to a stated conditionAll actions performed as a result of failure, to restore an item to a specified condition.

Preventive Maintenance (PM)All actions performed in an attempt to retain an item in specified condition by providing systematic inspection, detection, and prevention of incipient failureScheduled maintenance : Preventive maintenance performed at prescribed points in the items life

Which one will be held ???

Maintenance Strategy, stat v/s condt based Statistical based / reliability basedThe components must be replace/repair at the certain ageObjective : minimize total cost, fixed statistically optimal PM interval

Condition based / censored basedFeedback censor information used to perform maintenance planning decision

Which one will be held ???

Condition Based Maintenance (CBM)= Condition Monitoring = Predictive Maintenance (PdM)

Based on known condition

Action / activity in maintenanceWhile for every strategy, we can choose action / activity to maintain the system :

Repair, retaining or restoring the system to specified condition. There are 3 types of repair : minimal repair, perfect repair, imperfect repairReplace, change failed item with the new one

DEFINITION*

Condition Based MaintenanceMaintenance based on the condition of an asset.Asset: An item of value.Condition: The state of an item.

is the art of monitoring your equipments health by taking simple measurements of the machines performance.

Much the same way a Doctor will check (measure) your health by checking your pulse, temperature, blood pressure etcIf these measures are abnormal the doctor may suggest that they continue to take measurements but maybe more often. Or based on the first set of readings he may recommend some process changes such as, better diet, more rest etc. He bases his decisions on known values or a standard, on scientific research, or experience from training. Thankfully the medical profession has a good understanding of what is normal and what is not.

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Condition Monitoring :The non-invasive monitoring of systems to obtain knowledge of their condition; to distinguish wear, impending failure or other deterioration without disrupting the normal operation of those systems

Condition Based MaintenanceMaintenance requirements based on the performance or physical state of the system

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Predictive MaintenanceMeasurements that detect the onset of a degradation mechanism thereby allowing causal stressors to be eliminated or controlled prior to any significant deterioration in the component physical state. Results indicate current and future functional capability.

Schedule maintenance activities when mechanical or operational conditions warrant to repair or replace deteriorated equipment before obvious problems occur.

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Maintenance action based on actual condition (objective evidence of need) obtained from in-site, non-invasive tests, operating, and condition measurements.

kegiatan perawatan yang berhubungan dengan memonitor kondisi program perawatan preventif dimana metode memonitor secara langsung digunakan untuk menentukan kondisi peralatan secara teliti (Blanchard, 1980)

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PdM adalah pemeliharaan berdasarkan penilaian atau analisa kondisi (Condition Base) komponen atau peralatanKondisi itu harus dapat terukur (parameter terukur) seperti temperatur, tekanan, vibrasi, tingkat keausan, tingkat korosi (corrosion rate), tingkat keretakan, sisa umur kekuatan logam, viskositas minyak pelumas, konduktivitas air pendingin, daya mampu, efisiensi dan lain sebagainya. Parameter-parameter terukur ini secara periodik dimonitor. Apabila ada parameter yang mengalami gejala memburuk, maka monitoring harus lebih diintensifkan dan diprediksi kapan kerusakan sesungguhnya akan terjadi. Apabila suatu komponen peralatan atau peralatan tidak memberikan parameter terukur, maka Predictifve Maintenanace tidak dapat dilaksanakan.(Prajitno, 2005)

Predictive Maintenance

Predictive MaintenanceTimeline to FailureFailureNoticeable Performance DegradationStressor AppliedPreventive Maintenance ZonePredictive Maintenance Zone48 MonthsThermographyVibration AnalysisAcoustic AnalysisAdditional 8% - 12% savings over a good preventive maintenance program

Mitigation and RepairFix WhatBrokePrediction and PlanningDegradation Zone

Ada yang memandang PdM dimasukkan dalam PM karena keduanya saling berkaitanNamun ada yang melihat PM dan PdM sebagai dua hal yang berbedaPdM tidak menghilangkan PM. Interval waktu antar pemeliharaan diperpanjang (sesuai prediksi kondisi peralatan) dan volume pekerjaan pada setiap pemeliharaan bisa terukur (efektif) sesuai kebutuhanPredictive Maintenance

Advantages and DisadvantageAdvantageIncreased component operational life/availabilityAllows for preemptive corrective actionsDecrease in equipment or process downtimeDecrease in costs for parts and laborBetter product qualityImproved worker and environmental safetyImproved worker moraleEnergy SavingsField study showed a 8-12% savings over preventive maintenance programsDisadvantageIncreased investment in diagnostic equipmentIncreased investment in training of staffSavings potentials not readily seen by management

Barriers to adoptionLack of management commitmentFailure to change traditional maintenance practicesConcern about acceptance by OEMs, insurance and classTechnical complexityLack of independent adviseOverworked crew

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Key elements for successful implementation1. Clear maintenance policy Maintenance plans will be developed using best available techniques, appropriate to the equipment's HSE and performance criticality.A risk-based approach to extent and timing of maintenance activities will be used. For rotating equipment , condition monitoring techniques will be applied with a view to optimising equipment availability and eliminating cause of failures"2. Criticality analysisFocuses attention on equipment items (or systems), failure of which will significantly affect safety, health, the environment, or business performanceConsidersLikelihood of failureConsequence of failure

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3. Select appropriate maintenance task reactive, planned, onconditionRun-to-failureA decision, based on a systematic analysis, not to undertake preventive maintenanceE.g.- allowing a domestic fresh water pump to operate until it either ceases to pumpScheduled maintenanceMaintenance carried out in accordance with an established time scheduleE.g. overhaul fuel valves and replace nozzles every 8000 hoursCondition-based maintenanceMaintenance carried out according to the need indicated by condition monitoringE.g.- overhaul inert gas fan when vibration readings exceed limiting valuesRe-designA decision, based on a systematic analysis, to reduce the probability of failure by modification of the itemE.g.- re-design of a radar mast to reduce vibration-induced failures of a radar antenna

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4. For on-condition tasks, choose appropriate techniques, measurement intervals and limits. Identify failure modesIdentify physical characteristics associated with each failure modeDetermine a non-intrusive method of measuring each physical characteristic Set limiting values5. Establish training programme6. Measure performance of cm programme

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Tahapan PdMSetupMonitoringRepairInspection scheduleMengidentifikasikan peralatan dan prioritas item berdasar dampak kerusakanMenentukan bagaimana peralatan akan rusak menggunakan pengetahuan operator dan sejarah perawatanMenyusun jadwal inspeksiMengumpulkan informasi peralatan

Uji peralatan yang sesuai dan memasukkan data dalam database PdMMenganalisa dan memonitor pengukuran

Menyelidiki adanya kerusakan, jika perlu dilakukan perbaikanMenentukan panjang waktu sebelum kegagalan terjadiPerbaikan jadwal terjadi kerusakanMenggunakan leadtime dengan baik

P-F INTERVAL*

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exampleCracks in (railway) railsFrequency of initiated cracks depends on traffic load, rail material, rail geometry, particles on the rails, shocks from trains with non-circular wheels, and so onInspection by a special rail-car with ultrasonic inspection equipment (implies high cost)Detection probability depends on the depth of the crackPF interval is the time interval from the crack is observable until a critical failure occursA critical failure may involve derailment and fatalities (i.e., CC difficult to assess)

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CONDITION MONITORING TECHNIQUE*

Human Sensesight, touch, smell, hearing, (taste)

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Fluid Analysislubricants,greases, hydraulic oil

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Process parameter analysis temperatures, pressuresVibration and acoustics vibration analysis, shock pulse, acoustic emission

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thermographyTermal imaging*

Thickness measurement steel structure

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PERBEDAAN TIME BASE & CONDITION BASEMAINTENANCE

EXAMPLE*

Tribologi, kegiatan pemantauan kondisi minyak pelumas yang melibatkan pengetahuan tentang gesekan (friction) dari permukaan yang berinteraksiKualitas siklus air, pemantauan dan analisa sifat-sifat kimia air untuk mengetahui dampak kerusakan terhadap logam yang dilaluinyaVibrasi, kegiatan Pemantauan dan Analisa sifat sifat getaran peralatan, untuk mencari penyebab-penyebab getaran yang tidak normal.Termografi, pemantauan distribusi termal pada suatu permukaan dengan menggunakan radiasi infra merah, untuk mencari lokasi sumber panas yang tidak normal.Life assessment, kegiatan pemeriksaan, pengujian dan analisa penyebab kerusakan terhadap bagian-bagian komponen (logam) peralatan yang kritis

Obyek Pengamatan PdM

Nondestructive testing :Inframerah analysis, untuk memonitor kegagalan mekanik dan/atau kegagalan elektrik.Vibration Analysis, paling produktif pada putaran peralatan berkecepatan tinggi dan pada part yang paling mahalOil analysis, lebih bersifat prediksiAcoustical Analysis, dilakukan pada suatu tingkatan sonik hanya untuk peralatan mekanik. Sedangkan teknologi ultrasonik lebih fleksibel dan reliabel untuk mendeteksi permasalahan mekanik dan elektrik.

Teknologi yang digunakan

If you were measuring the current draw and the outlet flow of a pump and could see that the draw was increasing yet the outlet flow was decreasing, as compared to the measurements you had taken over the previous months, you would be right in assuming that the condition was deteriorating and that some maintenance was due for the pump, assuming of course that all the other variables had stayed the same such as the material the pump was pumping was the same etc. Flow and current cannot be measured on all the machines so you have to choose a measurement parameter that is more suitable for the majority of your equipment. Which technology you use will depend on the equipment you have. However vibration measurement is the most versatile and gives the most information which is why it is the most used measurement parameter.

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Equipment yang biasanya di PdM *

Example of degradation*

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*Regression Analysis

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Regression Analysis*

Regression Analysis*

Regression Analysis*

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Oil condition*

Wind turbine oil test*

Automotive : Coolant and new oil*

Gearbox : water in oil*

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Continuous Condition Monitoring*

communication*

Pokok-Pokok Manajemen PerawatanPokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Predictive Maintenance (PDM) advocates measurements aimed at the detection of degradation mechanisms themselves, thereby allowing the degradation to be understood and eliminated or controlled, prior to significant physical deterioration of the equipment.These usually nonintrusive measurement methods allows us to detect and correct the potential for degradation considerably earlier in the equipment degradation scenario. Technologies such as vibration analysis, oil analysis, thermography and condition monitoring pushes our problem recognition capability to the leading edge of the degradation envelope. So now our time line now looks like the one shown in the slide.The application of this technology results in : marked increased equipment life earlier corrective actions taken decreased process downtime decreases in maintenance parts and labor better product quality decreased environmental impact energy savings.The sum of these advantages adds another 8 to 12% to the savings over a good PM program. Root cause can usually be understood and, consequently, mitigation can be better targeted and repeating failures are history. On the negative side, the up-front investment in diagnostic equipment and the high level of staff training make this a more difficult pitch to an ever wary, cost conscious management. The savings are now usually in terms of avoided cost (a hard concept for management to grasp) and therefor become much more difficult to demonstrate and easier to forget.

Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*Pokok-Pokok Manajemen Perawatan*