Materi. Introduction In this discussion the appliaction of maintainability to the design process is addressed. The maintainability design process is similar.

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1 Materi

2 Introduction In this discussion the appliaction of maintainability to the design process is addressed. The maintainability design process is similar to that of reliability design. The overall maintainability goal must then be allocated to the repairable subassemblies and components.

3 Introduction The Maintainability Design Process

4 Measurements and Specifications

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7 If mean preventive maintenance time (MPMT) is to be included in the work hour calculation, then Where CREWpm is the average crew size for preventive maintenance

8 Measurements and Specifications Example Sebuah sistem mempunyai distribusi waktu perbaikan berdistribusi lognormal, dengan waktu median perbaikan 3,5 jam dan shape parameter s =0.18. Jika 95% perbaikan dapat diselesaikan dalam waktu 5 jam dan jumlah jam pemeliharaan harus kurang dari 3 jam setiap 100 jam operasi. Untuk memastikan jaminan pemeliharaan, maka 2 jam preventive maintenance harus dilakukan setiap 200 jam operasi. Jumlah crew pemeliharaan harus dilakukan oleh 2 orang dengan alasan keselamatan. Distribusi kegagalan berbentuk exponensial dengan MTBF 1000 jam oeprasi. Apakah persyaratan pemeliharaan terpenuhi ?

9 Maintenance Concepts and Procedures For a complex system consisting of subassemblies, components, and parts, it is neccessarty to determine the following: Which unit are to be repaired rather than discarded and replaced The preventive maintenance schedule and associated tasks. For each repairable units, the level of repair (such as local, service center, or factory ) for each failure mode. For each repair task, the required skill levels, tools, test equipment, and technical manuals. The number of repair channels and spare parts (inventory)

10 Cost Model

11 Example: Sebuah mesin dibeli dengan harga $3100. Biaya tetap kerusakan sebesar $75, dan biaya variabel kerusakan berdasarkan tenaga crew dengan biaya $50 per jam. Perusahaan pembuat mesin (manufacturer) tersebut menjamin, bahwa kebutuhan perawatan dari semua jenis kegagalan pada 1000 jam kerja pertama. Berdasarkan desain saat ini dan pengujian yang dilakukan menunjukan MTBF sebesar 40 jam kerja, dan MTTR 6 jam. Dalam upaya mengurang biaya jaminan tersebut, manufcturer dapatt meningkatkan MTBF sebesar 20% atau meningkatkan MTTR sebesat 20%. Mana pilihan yang terbaik, dengan asumsi dari kedua pilihan tersebut meningkatkan biaya sebesar $1000.

12 Component Reliability and Maintainability

13 Example Sebuah mesin foto copy mempunyaia beberapa komponen penyusun sebagai berikut: Control Unit Input Tray System Camera Unit Feeder System Power Unit Quantity (qi) 12121 0.00160.0080.0010.0210.005 Persyaratan spesifikasi rata-rata waktu perbaikan sebesar 4 jam. Tentukan alokasi MTTR yang cocok untuk setiap komponen. Asumsikan waktu operasi semua komponen sama, serta memiliki constant failure rate.

14 Design Methods Fault Isolation and Sel-Diagnostics Diagnostics can take several forms such as Manual, Automatic, and Self Diagnostic Parts Standarization and Interchangeability Modularization and Accessibility Repair versus Replacement Proactive Maintenance Two type of proactive maintenance are preventive maintenance and predictive maintenance.

15 Human Factor and Ergonomics Huma factor or ergonomics is concerned with the interaction of humans with the physicl objects they encounter in performing their activities. In maintenance system design, we are concerned with the ergonomics subtopics of antropometry, biomechanics, physiocology, psychophysics, human perception and human performance. The physical design of the equipment must provide for personel access to all failed components.

16 THANK YOU...... For your attention............