Production Planning

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Transcript of Production Planning

  • Hasil prakiraan permintaan produk suatu industri selama bulan Januari s/d April 2009 serta jumlah hari kerja efektif per bulan disajikan pada Tabel berikut:

    Jam kerja reguler per hari adalah 8 jam kerja, dan apabila diperlukan perusahaan menerapkan jam lembur . Pada bulan Desember 2008 jumlah tenaga kerja yang ada adalah sebanyak 50 orang. Berdasarkan hasil pengukuran kerja, waktu standar untuk menghasilkan 1 unit produk adalah 5 jam kerja-orang. Pada akhir bulan Desember 2008 diprediksi bahwa stok produk yang ada adalah sebesar 300 unit. Diketahui bahwa upah tenaga kerja pada Jam reguler adalah Rp. 8000/jam/orang, dan jika bekerja lembur maka upah nya adalah Rp. 12000/jam./orang. Perusahaan mengambil kebijakan:

    Sheet1

    BulanPermintaan (unit)Hari kerja

    Januari250024

    Februari150020

    Maret225024

    April220024

    Sheet2

    Sheet3

  • Tidak melakukan penambahan atau pengurangan tenaga kerja, serta boleh terjadi kelebihan stok tetapi tidak boleh terjadi kekurangan stok produk. Apabila produksi melebihi permintaan, maka biaya penyimpanan produk adalah sebesar Rp. 4000/unit/bulan. Untuk perencanaan produksi 4 bulan mendatang manajemen menetapkan skenario, yaitu: Melakukan produksi untuk memenuhi permintaan pada jam reguler dan jika terjadi kekurangan, kekurangannya dipenuhi dengan berproduksi pada jam lembur dengan ketentuan maksimal 3 jam per orang per hari.Berapa kali dalam periode perencanaan perusahaan mengalami kelebihan stok produk.Berapa total biaya produksi dengan skenario yang diambil oleh manajemen.

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    Aggregate Planning Example Computer Application

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    Aggregate Planning Example Computer Application

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    Aggregate Planning Example

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    Master Production Scheduling (MPS)(Jadwal Induk Produksi)

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    Objectives of MPSDetermine the quantity and timing of completion of end items over a short-range planning horizon.Schedule end items (finished goods and parts shipped as end items) to be completed promptly and when promised to the customer.Avoid overloading or underloading the production facility so that production capacity is efficiently utilized and low production costs result.

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    Time Fences The rules for schedulingNo Change+/- 5%

    Change+/- 10%

    Change+/- 20%

    ChangeFrozenFirmFullOpen1-2 weeks2-4weeks4-6weeks6+ weeks

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    Time FencesThe rules for scheduling:Do not change orders in the frozen zoneDo not exceed the agreed on percentage changes when modifying orders in the other zonesTry to level load as much as possibleDo not exceed the capacity of the system when promising orders.If an order must be pulled into level load, pull it into the earliest possible week without missing the promise.

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    Developing an MPSUsing input informationCustomer orders (end items quantity, due dates)Forecasts (end items quantity, due dates)Inventory status (balances, planned receipts)Production capacity (output rates, planned downtime)Schedulers place orders in the earliest available open slot of the MPS. . . more

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    Developing an MPSSchedulers must:estimate the total demand for products from all sourcesassign orders to production slotsmake delivery promises to customers, andmake the detailed calculations for the MPS

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    Example: Master Production SchedulingArizona Instruments produces bar code scanners for consumers and other manufacturers on a produce-to-stock basis. The production planner is developing an MPS for scanners for the next 6 weeks.The minimum lot size is 1,500 scanners, and the safety stock level is 400 scanners. There are currently 1,120 scanners in inventory. The estimates of demand for scanners in the next 6 weeks are shown on the next slide.

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    Example: Master Production SchedulingDemand Estimates

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    Example: Master Production SchedulingComputationsCUSTOMERS BRANCH WAREHOUSES MARKET RESEARCH PRODUCTION RESEARCH50020001010503001000005004002342000003005000100700651000200WEEKTOTAL DEMAND BEGINNING INVENTORY REQUIRED PRODUCTIONENDING INVENTORY7101120041056015004101350116015009005607001250950460460116015001500010101200950

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    Example: Master Production SchedulingMPS for Bar Code Scanners

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    Rough-Cut Capacity PlanningAs orders are slotted in the MPS, the effects on the production work centers are checkedRough cut capacity planning identifies underloading or overloading of capacity

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    Example: Rough-Cut Capacity PlanningTexprint Company makes a line of computer printers on a produce-to-stock basis for other computer manufacturers. Each printer requires an average of 24 labor-hours. The plant uses a backlog of orders to allow a level-capacity aggregate plan. This plan provides a weekly capacity of 5,000 labor-hours.Texprints rough-draft of an MPS for its printers is shown on the next slide. Does enough capacity exist to execute the MPS? If not, what changes do you recommend?

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    Example: Rough-Cut Capacity PlanningRough-Cut Capacity AnalysisPRODUCTION10020020028025012345WEEKTOTAL1030LOAD2400480048006720600024720CAPACITY5000500050005000500025000UNDER or OVER LOAD260020020017201000280

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    Example: Rough-Cut Capacity PlanningRough-Cut Capacity AnalysisThe plant is underloaded in the first 3 weeks (primarily week 1) and it is overloaded in the last 2 weeks of the schedule.Some of the production scheduled for week 4 and 5 should be moved to week 1.

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    Demand ManagementReview customer orders and promise shipment of orders as close to request date as possibleUpdate MPS at least weekly.... work with Marketing to understand shifts in demand patternsProduce to order..... focus on incoming customer ordersProduce to stock ..... focus on maintaining finished goods levelsPlanning horizon must be as long as the longest lead time item

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    Types of Production-Planning and Control Systems

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    Types of Production-Planningand Control SystemsPond-Draining SystemsPush SystemsPull SystemsFocusing on Bottlenecks

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    Pond-Draining SystemsEmphasis on holding inventories (reservoirs) of materials to support productionLittle information passes through the systemAs the level of inventory is drawn down, orders are placed with the supplying operation to replenish inventoryMay lead to excessive inventories and is rather inflexible in its ability to respond to customer needs

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    Push SystemsUse information about customers, suppliers, and production to manage material flowsFlows of materials are planned and controlled by a series of production schedules that state when batches of each particular item should come out of each stage of productionCan result in great reductions of raw-materials inventories and in greater worker and process utilization than pond-draining systems

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    Pull SystemsLook only at the next stage of production and determine what is needed there, and produce only thatRaw materials and parts are pulled from the back of the system toward the front where they become finished goodsRaw-material and in-process inventories approach zeroSuccessful implementation requires much preparation

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    Focusing on BottlenecksBottleneck OperationsImpede production because they have less capacity than upstream or downstream stagesWork arrives faster than it can be completedBinding capacity constraints that control the capacity of the systemOptimized Production Technology (OPT)Synchronous Manufacturing

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    Synchronous ManufacturingOperations performance measured bythroughput (the rate cash is generated by sales)inventory (money invested in inventory), andoperating expenses (money spent in converting inventory into throughput). . . more

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    Synchronous ManufacturingSystem of control based on: drum (bottleneck establishes beat or pace for other operations)buffer (inventory kept before a bottleneck so it is never idle), andrope (information sent upstream of the bottleneck to prevent inventory buildup and to synchronize activities)

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    Wrap-Up: World-Class PracticePush systems dominate and can be applied to almost any type of productionPull systems are growing in use. Most often applied in repetitive manufacturingFew companies focusing on bottlenecks to plan and control production.

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    End of Chapter 13

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