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Latihan

Soal-soal

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= failure rate, maka = 1/MTBF

m = repair rate, maka m = 1/MTTR

Availability = MTBF/(MTBF+MTTR)MTBF tak hinggaMTTR 0

Maintenance Ratio,economic;

MC total maintenance cost---- = -----------------------------PC total production cost

MC total maintenance cost---- = -----------------------------IE value of idle equipment maintained

RUMUS-RUMUS PENTING DALAM PENYELESAIAN SOALMANAJEMEN PEMELIHARAAN

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Operating Ratio

number of good items producedProduction Ratio = -----------------------------------------

number theoritically possible

number of good items producedProductivity ratio = --------------------------------------

tinme taken

number of good items producedTrue productivity = ------------------------------------------

machine runing time + downtime

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Availability Ratios.

Time required for productionEquipment duty ratio = -------------------------------------------

total time

total machine timeOperational availability = -----------------------------------------

Time required for production

total machine timeTrue Availability = --------------------------------------

machine time + down time

total machine time

Over all Availability = -----------------------------------------------------machine running time + maintenance time

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MTBF = Mean Time Between FailureMTTR = Mean Time to RepairMTTF = Mean Time To Failure

MUT = Mean Up TimeMDT = Mean Down Time

MUTMTTR

MDT

MTBF

t

Running

Stopped

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1. Menghitung Productivity suatu kebijakan pemeliharaan.

Rumus :

Productivity = Utilization X Methods X Performance.

2. Menghitung Overall equipment Effectiveness (OEE).Rumus :

OEE = Availability X Efficiency X Quality

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1. Menghitung Maintenance Productivity (produktivitas pemeliharaan).

Rumus :

Productivity = Utilization X Methods X Performance.

Keterangan :

Utilization, Methods dan Performance umumnya dinyatakan dalam bentukprosentase dari kriteria yang diinginkan,sebagai contoh, bila diketahui tingkatutilization, methods dan performance suatu perangkat berturut-turut adalah65 %, 50 % dan 75 %, maka

Productvity = 0.65 X 0.50 X 0.75 = 0.24 atau 24 %

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2. Menghitung Overall equipment Effectiveness (OEE).

Rumus :

OEE = Availability X Efficiency X Quality

Keterangan :

a. Availability.

Operation timeAvailability = ------------------------

Net Available time

Net available time = Total available time Planned Down timeIf Unplanned down time occurs (Uncontrolled)Net available time =

Total available time Planned down time Unplanned down time.

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Keterangan :

b. Efficiency.

Theoretical Production timeEfficiency = -----------------------------------

Actual Production time.

c. Quality .

Acceptable partsQuality = -------------------------------

Total Parts produced

Number of accepted parts = Total Parts Produced Rejected Parts.

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Contoh Soal :

1. Suatu perangkat produksi mempunyai data catatan kinerja sebagaiberikut :Loading time = 20 jam.Down time = 120 menit.Waktu siklus = 0.50 menit per unitJumlah produk yang dproses = 2000 unit,

Jumlah produk cacat = 100 unit

Hitung :a. Overall Equipment Effectivenessb. Dengan penerapan program PM, ternyata

memperoleh peningkatan proses yaitu pengurangan

set-up time peralatan 60 menit, dan produk yangcacat menjadi hanya 50 unit saja. Berapa OEE sekarang?

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Jawaban a OEE = Availability x efficiency x quality 1.Availability

Loading time = 20 jam operating time = Downtime = 2 jam 20 2 = 18 jam AV = 18 jam = 0.9 = 90 %

20 jam 2. Efficiency

Waktu siklus = 0,5 menit / unit produksi = 2 unit/menit Operaing time = 18 jam P18 jam = 18 x 60 x 2 = 2160 unit

Output ( jumlah produk yang diproses) = 2000 unit Performance eff = 2000 unit = 0,93 % = 93 %

2160 3. Quality

Produk cacat = 100 unit Produk seluruhnya = 2000 unit Rate of quality ( ROQ) = 2000-100 = 0,95 = 95 %

2000 OEE = AV X EFF X ROQ = 0,90 x 0,93 x 0,95 = 0,79 = 79 %

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OEE = Availability x efficiency x quality 1.Availability

Loading time = 20 jam operating time = Downtime = 1 jam 20 1 = 19 jam AV = 19 jam = 0.9 = 95 %

20 jam 2. Efficiency

Waktu siklus = 0,5 menit / unit

produksi = 2 unit/menit Operaing time = 19 jam P19 jam = 19 x 60 x 2 = 2280 unit Output ( jumlah produk yang diproses) = 2000 unit Performance eff = 2000 unit = 0,87 % = 87 %

2280 3. Quality

Produk cacat = 50 unit Produk seluruhnya = 2000 unit Rate of quality ( ROQ) = 2000-50 = 0,97 = 97 %

2000 OEE = AV X EFF X ROQ = 0,95 x 0,87 x 0,97 = 0,80 = 80 %

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Contoh Soal :

2. Suatu perangkat produksi mempunyai data catatan kinerja sebagai berikut :Kebutuhan persediaan berdasarkan data biaya, pemesanan, harga,

kerusakan yang terjadi,dll, diperoleh kebutuhan komponen KK007 untukkegaiatan operasi dan pemeliharaan sebagai berikut :

Hitung :a. Berapa jumlah persediaan optimal komponen ?b. Berapa biaya persediaan?

Bila diketahui biaya kelebihan persediaan per unit =$ 20.-dan biaya kekurang persediaan per unit = $ 50.-

Kebutuhan komponen perbulan

Kejadian (kali)

10 10

20 20

30 15

35 15

40 20

65 20

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