Rahma Rei Sakura, S.T., M.T. NIP MANAJEMEN OPERASIONAL PRODUKSI

Transkripsi

1 Rahma Rei Sakura, S.T., M.T. NIP MANAJEMEN OPERASIONAL PRODUKSI

2 AGGREGATE PLANNING MANAJEMEN OPERASIONAL PRODUKSI

3 Long range Intermediate range Manufacturing Forecasting & demand management Master scheduling Process planning Strategic capacity planning Sales and operations (aggregate) planning Sales plan Aggregate operations plan Services Material requirements planning Short range Order scheduling Weekly workforce and customer scheduling Daily workforce and customer scheduling MANAJEMEN OPERASIONAL PRODUKSI

4 Introduction Warehouse Food Mart Factory Aggregate Planning Retailer End Consumer MANAJEMEN OPERASIONAL PRODUKSI

5 Contoh : Sebuah perusahaan menjual beberapa kelompok produk dibeberapa wilayah yang berbeda, maka ramalan bisa dibuat secara agregat untuk semua kelompok produk dan semua wilayah, atau untuk setiap kelompok produk, setiap wilayah, atau bahkan pada level yang lebih detail yaitu pada level individu produk. Agregasi juga dapat dibuat berdasarkan waktu, sehingga angka ramalan dapat dibuat untuk periode harian, mingguan, bulanan, atau tahunan. MANAJEMEN OPERASIONAL PRODUKSI

6 Tujuan utama dari aggregate planning yaitu untuk menentukan kombinasi dari production rate, work-force level, dan inventory on hand. Production Rate jumlah unit yang diproduksi untuk setiap periode tertentu. Work-force level jumlah pekerja yang dibutuhkan untuk setiap produksi pada periode tertentu. (production = production rate x workforce level). Inventory on hand jumlah persediaan yang tidak digunakan dari periode sebelumnya. MANAJEMEN OPERASIONAL PRODUKSI

7 Introduction Definisi the aggregate planning consists of determining how feasible production alternatives must be employed in each period to satisfy expected demand at minimum total production cost. (Kostas N. Dervitsiotis, 1981) Suatu pernyataan tingkat produksi yang direncanakan dalam bentuk aggregate yang mengintegrasikan antara operasi manufaktur dengan rencana marketing dan bisnis. Melibatkan pemilihan strategi manufaktur. Input utama untuk Resource Planning. Menstabilkan produksi dan tenaga kerja apabila pola demand bervariasi. Dinyatakan dalam bentuk famili atau group produk, bukan specific model. MANAJEMEN OPERASIONAL PRODUKSI

8 Introduction Ukuran unit pada setiap perusahaan berbeda-beda (ton, gallon, cases, yards, kubik atau berdasarkan input yang digunakan dalam produksi seperti man hours atau machine hours). Note : digunakan untuk faktor konversi agar perencanaan produksi dapat secara langsung dikaitkan dengan rencana marketing dan bisnis Untuk produk dimana unit dalam family relatif homogen dapat dinyatakan dalam unit produk (cost dollars). Format tidak standard. MANAJEMEN OPERASIONAL PRODUKSI

9 Production Plan (Make To Order) PRODUCTION PLAN Product Family : Pumps Date Issued : 12/30/xx Unit of Measure : Dollars at cost MONTH JAN FEB MAR APR MAY WORKING DAYS PAST DUE Forecast 568, , , , ,000 Order Backing 175, , , , , ,720 Production Plan 623, , , , ,000 Planned Daily Rate 28,322 28,322 17,361 29,714 28,696 Shipping Forecast 623, , , , ,000 MANAJEMEN OPERASIONAL PRODUKSI

10 Production Plan (Make To Stock) PRODUCTION PLAN Product Family : Valves Date Issued : 6/1/xx Unit of Measure : Each MONTH JUNE JULY AUG SEPT OCT WORKING DAYS PAST DUE Forecast 2,460 2,500 2,700 3,000 2,500 Production Plan 2,603 2,726 2,852 2,480 2,500 Planned Daily Rate Shipping Forecast 2,460 2,500 2,700 3,000 2,500 Planned Ending Inventory 1,240 1,383 1,611 1,763 1,243 1,243 MANAJEMEN OPERASIONAL PRODUKSI

11 Strategi Aggregate Planning 1. Capacity options Mengubah-ubah tingkat inventory (level inventory) Mengubah-ubah ukuran tenaga kerja: hiring / lay off (chase strategy) Mengubah-ubah production rate: over time / under time Menggunakan part time workers MANAJEMEN OPERASIONAL PRODUKSI

12 Strategi Aggregate Planning 2. Demand options Mempengaruhi demand advertising (periklanan), promosi, personal selling, discount, diskriminasi harga Backordering 3. Pure strategies Bila yang diubah-ubah hanya satu variabel 4. Mixed Options Melibatkan pengubahan beberapa variabel, misalnya bila pure strategy tidak feasible MANAJEMEN OPERASIONAL PRODUKSI

13 Fase-fase Aggregate Planning Periodically Phase 2 Smooth out capacity utilization Phase 3 Determine feasible production alternative Phase 1 Forecast aggregate demand Regularly Phase 4 Allocate demand to production periods Time series with seasonals Moving averages Exponential smoothing Others Complementary products Pricing Promotion Flexibility delivery times Fixed work force - Overtime - Undertime Variable work force - Hiring - Layoffs Inventory Backordering Linear costs Trial and Error Linear Programming - Transportation - Simplex Nonlinear Costs Linear decision rule Subcontracting Others Heuristic and search models MANAJEMEN OPERASIONAL PRODUKSI (suitable for all type of costs) 13

14 Fase-fase Aggregate Planning Phase I : Preparation of an Aggregate Demand Forecast Forecast dalam satuan unit yang sama untuk semua jenis item produk Phase II : Specification of Organization Policies for Smoothing Capacity Utilization Membuat policy untuk merealisasikan perencanaan agregat yang telah diramalkan sebelumnya untuk mengantisipasi unstationary demand dengan melibatkan marketing dan produksi Contoh: diskon, promosi, dll MANAJEMEN OPERASIONAL PRODUKSI

15 Fase-fase Aggregate Planning Phase III : Determination of Feasible Production Alternatives Changing the production rate with the same work force Changing production rate by changing the size of work force Absorbing demand through inventories Absorbing demand by backordering Absorbing demand by subcontracting MANAJEMEN OPERASIONAL PRODUKSI

16 Fase-fase Aggregate Planning Phase IV : Determination of Optional Production Strategy Menentukan strategi yang optimal dengan alokasi demand forecast dengan alternatif-alternatif produksi yang meminimumkan biaya total selama horizon perencanaan MANAJEMEN OPERASIONAL PRODUKSI

17 Aggregate Plan Managerial Inputs Operations Current machine capacities Plans for future capacities Workforce capacities Current staffing level Distribution and marketing Customer needs Demand forecasts Competition behavior Materials Supplier capabilities Storage capacity Materials availability Aggregate plan Engineering New products Product design changes Machine standards Human resources Labor-market conditions Training capacity MANAJEMEN OPERASIONAL PRODUKSI

18 Aggregate Plan Outputs Aggressive Alternatives Complementary Products Competitive Pricing Reactive Alternatives Size of Workforce and Workforce Adjustment Aggregate plan Units or dollars of Backlogs, backorders, or stockout Inventory Levels Production per month (in units or $) Units or dollars subcontracted MANAJEMEN OPERASIONAL PRODUKSI

19 Controllable (Decision) Variable Inventory Production rate Manpower Capacity : overtime / recruitment / layoff (tenaga kerja / workforce) Subcontract MANAJEMEN OPERASIONAL PRODUKSI

20 Relevant Cost Hiring/layoff cost Overtime/undertime cost Inventory carrying cost Subcontracting incremental cost Part time labor cost Backorder cost MANAJEMEN OPERASIONAL PRODUKSI

21 Aggregate Planing Objectives MANAJEMEN OPERASIONAL PRODUKSI

22 Total Cost Production cost in period t Cost of regular production Cost of units overtime production Cost of unit used from inventory Cost of backordering Cost of hiring Cost of firing Cost of subcontracting TC C 1 C 2 C t MANAJEMEN OPERASIONAL PRODUKSI

23 Total Cost Production alternative Demand forecast Allocation amount, units Unit costs Total costs Subcontracting 80 $12 $960 Internal capacity Inventory Overtime production D5= * 120 $1 $8 $400 $960 Regular production 300 $5 $1,500 Total Cost at period 5 $3, * The 200 units form inventory were produce in period 3 MANAJEMEN OPERASIONAL PRODUKSI

24 Methods Trial and Error (Charting/Graphical Methods) Pure strategy Mixed strategy Mathematical (Optimal) Approach Linear Programming Model Transportation Model Empirical Approach Simulation Berdasarkan asumsi hubungan biaya yang digunakan, metode aggregate planning dapat dibedakan menjadi: 1. Linear cost relationships (Metode LDR) 2. Non-linear cost relationships (Metode Bowman) MANAJEMEN OPERASIONAL PRODUKSI

25 Klasifikasi Metode Aggregate Planning Aggregate planning method Linear Cost relationships Nonlinear Not yielding optimal plan Yielding optimal plan A. Trial and error: Using table Using graph B. Linear programming Transportation method Simplex method C. Heuristic models and Computer search models D. Linear decision rule Dynamic programming MANAJEMEN OPERASIONAL PRODUKSI

26 Sistem Aggregate Planning Constraints Capacity limits for production alternatives Decision Allocate demand to production periods using feasible alternatives Input Output Period-by-period demand forecasts Feasible production alternatives Cost data on item 2 Initial condition Aggregate Planning Production rate Work-force size Desired inventory Amount of subcontracting Performance criteria (Minimize total production cost) MANAJEMEN OPERASIONAL PRODUKSI

27 Trial and Error Contoh : Diketahui demand selama 8 kuartal ke depan (hasil ramalan) Ongkos kenaikan tingkat produksi : $ 100 Ongkos penurunan tingkat produksi : $ 150 Ongkos inventory : $ 50 Incremental cost for subcontracting : $ 80 MANAJEMEN OPERASIONAL PRODUKSI

28 Kuantitas demand Trial and Error Forecast demand per Kuartal Kuartal Demand Kumulatif Demand per kuartal Kuartal MANAJEMEN OPERASIONAL PRODUKSI

29 Units Trial and Error Level Strategy (2) Business Cycle Production Time Periods MANAJEMEN OPERASIONAL PRODUKSI

30 Trial and Error Level Strategy (1) Kuartal Demand Production Adjusted Ongkos Level Inventory Inventory *) inventory Total *) Initial inventory: 270 MANAJEMEN OPERASIONAL PRODUKSI

31 Units Trial and Error Chase Strategy (3) Business Cycle Production Time Periods MANAJEMEN OPERASIONAL PRODUKSI

32 Trial and Error Chase Strategy (3) Kuartal Demand Hiring Layoff Total Total MANAJEMEN OPERASIONAL PRODUKSI

33 Trial and Error Subcontract Strategy Kuartal Demand Production Incremental Subcontract level cost , , , , , , ,600 Total 108,800 MANAJEMEN OPERASIONAL PRODUKSI

34 Units Aggregate Planning Strategy - Hybrid Business Cycle Production rate break Time Periods MANAJEMEN OPERASIONAL PRODUKSI

35 AGGREGATE PLANNING STRATEGIES Chase Strategy using capacity as the lever Time flexibility from workforce or capacity strategy using utilization as the lever Level Strategy using inventory as the lever MANAJEMEN OPERASIONAL PRODUKSI

36 CHASE STRATEGY The production rate is synchronized with the demand rate by varying machine capacity or hiring and lying off employees as the demand rate varies. This strategy can be expensive to implement if the cost of varying machine or labor capacity over time is high. The Chase Strategy results in low levels of inventory in the supply chain and high levels of change in capacity and workforce. It should be used when the cost of carrying inventory is very high and costs to change levels of machine and labor capacity are low. Chase Strategy Merubah Kapasitas MANAJEMEN OPERASIONAL PRODUKSI

37 Time Flexibility from Workforce or Capacity Strategy This strategy may be used if there is excees machine capacity. For example, machine are not used 24 hours a day, 7 days a week. In this case, the workforce (capacity) is kept stable but the number of hours worked is varied over time in an effort to synchronize produck with demand. This strategy result in low levels of inventory but with lower average machine capacity is relatively inexpensive. MANAJEMEN OPERASIONAL PRODUKSI

38 LEVEL STRATEGY A stable machine capacity and workforce are maintained with a constant output rate. Shortages and surpluses result in inventory levels fluctuating over time. In this case, production is not synchronized with demand. Employees benefit from stable working conditions. A drawback associated with this strategy is that large inventories may accumulate and customer orders may be delayed. This strategy keeps capacity and costs of changing capacity relatively low. It should be used when inventory carrying and backlog costs are relatively low. Level Strategy Kapasitas Tetap, Produksi Konstan MANAJEMEN OPERASIONAL PRODUKSI

39 MAIN OBJECTIVE MANAJEMEN OPERASIONAL PRODUKSI

40 MAIN OBJECTIVE a. Production Rate : jumlah unit yang dapat diselesaikan setiap unit waktu tertentu. (misal, setiap minggu atau setiap bulan). b. Workforce : jumlah dari pekerja setiap unit dari kapasitas yang dibutuhkan untuk melakukan produksi. c. Overtime : jumlah dari waktu lembur perencanaan produksi. d. Machine Capacity Level : jumlah unit dari kapasitas mesin yang dibutuhkan untuk produksi. e. Subcontracting : kebutuhan kapasitas yang disubkontrakkan pada satu perencanaan waktu tertentu. f. Backlog : permintaan yang tidak dipenuhi, yang muncul pada periode tertentu tetapi akan dipenuhi pada periode yang akan datang. g. Backorder : permintaan yang tidak terpenuhi, tetapi pelanggan masih mau menunggu untuk memproduksi barang tersebut. MANAJEMEN OPERASIONAL PRODUKSI

41 MAIN OBJECTIVE h. Safety Stock : jumlah produk yang diproduksi pada satu periode tertentu dan digunakan ketika jumlah permintaan lebih besar dari jumlah unit produksi. i. Inventory : persediaan (stok) dari suatu item atau sumber daya yang digunakan dalam suatu perusahan. j. Inventory on Hand : jumlah persediaan yang tidak digunakan dari periode sebelumnya. k. Shortage / Stock out : jumlah demand > jumlah supply. MANAJEMEN OPERASIONAL PRODUKSI

42 LEARNING OBJECTIVES 1. Identify the decisions that are best solved by aggregate planning. (capacity, production, and inventory) 2. Understand the importance of aggregate planning as a supply chain activity. (customers and supplier) 3. Describe the information needed to produce an aggregate plan. (cost and production information) 4. Explain the basic trade-offs to consider when creating an aggregate plan. (cost of capacity, inventory, stockout) 5. Formulate and solve aggregate planning problems using Microsoft Excel. MANAJEMEN OPERASIONAL PRODUKSI

43 ADA PERTANYAAN? MANAJEMEN OPERASIONAL PRODUKSI