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

Rahma Rei Sakura, S.T., M.T. NIP. 153112

MANAJEMEN OPERASIONAL PRODUKSI - 16027304

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AGGREGATE PLANNING


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Process planning Long range

Strategic capacity planning

Intermediate range

Forecasting & demand management

Sales and operations (aggregate) planning Sales plan

Manufacturing

Aggregate operations plan Services

Master scheduling

Material requirements planning

Short range

Order scheduling

Weekly workforce and customer scheduling

Daily workforce and customer scheduling MANAJEMEN OPERASIONAL PRODUKSI - 16027304

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Introduction Warehouse

Food Mart

Aggregate Planning

Retailer

Factory

End Consumer MANAJEMEN OPERASIONAL PRODUKSI - 16027304

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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.


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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.


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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.

   


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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.


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Production Plan (Make To Order)

PRODUCTION PLAN Product Family : Unit of Measure : MONTH WORKING DAYS Forecast Order Backing Production Plan Planned Daily Rate Shipping Forecast

Pumps Dollars at cost JAN PAST DUE 22 568,724 175,423 568,724 623,075 28,322 623,075


Date Issued : 12/30/xx

FEB 21 473,681 473,681 594,753 28,322 594,753

MAR 22 381,942 381,942 381,942 17,361 381,942

APR 21 624,000 426,835 624,000 29,714 624,000

MAY 23 660,000 328,720 660,000 28,696 660,000

… … … … … … …

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Production Plan (Make To Stock)

PRODUCTION PLAN Product Family : Valves Unit of Measure : Each MONTH WORKING DAYS Forecast Production Plan Planned Daily Rate Shipping Forecast Planned Ending Inventory

Date Issued : 6/1/xx

JUNE PAST DUE 21 2,460 2,603 124 2,460 1,240 1,383


JULY 22 2,500 2,726 124 2,500 1,611

AUG 23 2,700 2,852 124 2,700 1,763

SEPT 20 3,000 2,480 124 3,000 1,243

OCT 23 2,500 2,500 109 2,500 1,243

… … … … … …

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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


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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


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Fase-fase Aggregate Planning Phase 2

Phase 3

Smooth out capacity utilization

Determine feasible production alternative

Periodically

Phase 1

Phase 4

Regularly

Forecast aggregate demand

Allocate demand to production periods

Time series with seasonals

Complementary products

Moving averages

Pricing

Fixed work force - Overtime - Undertime

Linear costs Trial and Error

Exponential smoothing

Promotion

Others

Flexibility delivery times

Variable work force - Hiring - Layoffs

Linear Programming - Transportation - Simplex

Inventory Nonlinear Costs Backordering Linear decision rule Subcontracting


Others

Heuristic and search models (suitable for all type of costs)

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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


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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


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

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


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Aggregate Plan – Managerial Inputs Distribution and marketing Customer needs Demand forecasts Competition behavior

Operations Current machine capacities Plans for future capacities Workforce capacities Current staffing level

Materials Supplier capabilities Storage capacity Materials availability

Aggregate plan

Engineering New products Product design changes Machine standards MANAJEMEN OPERASIONAL PRODUKSI - 16027304

Human resources Labor-market conditions Training capacity 17

Aggregate Plan – Outputs Aggressive Alternatives Complementary Products

Competitive Pricing

Reactive Alternatives Size of Workforce and Workforce Adjustment

Inventory Levels


Aggregate plan

Production per month (in units or $)

Units or dollars of Backlogs, backorders, or stockout

Units or dollars subcontracted 18

Controllable (Decision) Variable  Inventory  Production rate

 Manpower  Capacity : overtime / recruitment / layoff (tenaga kerja / workforce)

 Subcontract


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Relevant Cost  Hiring/layoff cost  Overtime/undertime cost  Inventory carrying cost

 Subcontracting incremental cost  Part time labor cost  Backorder cost


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Aggregate Planing Objectives


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Total Cost Production cost Cost of regular Cost of units overtime   in period t production production Cost of unit used Cost of Cost of    from inventory backordering hiring Cost of Cost of   firing subcontracting

TC  C1  C2   Ct MANAJEMEN OPERASIONAL PRODUKSI - 16027304

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Total Cost Demand forecast

Allocation amount, units

Unit costs

Total costs

$12

$960

Subcontracting

80

Inventory

200*

$1

$400

120

$8

$960

300

$5

$1,500

D5=700

Internal capacity

Production alternative

Overtime production

Regular production

Total Cost at period 5 4

5

$3,820

6 * The 200 units form inventory were produce in period 3


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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)


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Klasifikasi Metode Aggregate Planning Aggregate planning method

Cost relationships

Linear

Nonlinear

Not yielding optimal plan

A. Trial and error: ▪ Using table ▪ Using graph

Yielding optimal plan

B. Linear programming D. Linear decision rule ▪ Transportation Dynamic programming method ▪ Simplex method


C. Heuristic models and Computer search models

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Sistem Aggregate Planning Constraints

Decision

Capacity limits for production alternatives

Allocate demand to production periods using feasible alternatives

Input

Output

Period-by-period demand forecasts Feasible production alternatives

Production rate

Aggregate Planning

Work-force size

Cost data on item 2

Desired inventory

Initial condition

Amount of subcontracting

Performance criteria MANAJEMEN OPERASIONAL PRODUKSI - 16027304

(Minimize total production cost)

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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


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Trial and Error Forecast demand per Kuartal

Demand Kumulatif 220 220 170 390 400 790 600 1390 380 1770 200 1970 130 2100 300 2400


Demand per kuartal Kuantitas demand

Kuartal 1 2 3 4 5 6 7 8

800 600 400 200 0 1

2

3

4

5

6

7

8

Kuartal

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Trial and Error Level Strategy (2)

Units

Business Cycle Production

1

2

3


4

5

6 7 8 9 10 11 Time Periods

12 13 29

Trial and Error Level Strategy (1) Kuartal

Demand

1 2 3 4 5 6 7 8

220 170 400 600 380 200 130 300

*) Initial

Production Level 300 300 300 300 300 300 300 300

Inventory 80 210 110 -190 -270 -170 0 0

Adjusted Ongkos Inventory*) inventory 17.500 350 24.000 480 19.000 380 4.000 80 0 0 5.000 100 13.500 270 13.500 270 96.500 Total

inventory: 270


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Trial and Error Chase Strategy (3)

Units


1

2

3


4

5

6 7 8 9 10 11 Time Periods

12 13 31

Trial and Error Chase Strategy (3) Kuartal Demand 1 220 2 170 3 400 4 600 5 380 6 200 7 130 8 300 MANAJEMEN OPERASIONAL PRODUKSI - 16027304

Hiring 0 0 23.000 20.000 0 0 0 17.000

Layoff 0 7.500 0 0 33.000 27.000 10.500 0 Total

Total 0 7.500 23.000 20.000 33.000 27.000 10.500 17.000 138.000 32

Trial and Error Subcontract Strategy Kuartal Demand 1 2 3 4 5 6 7 8

220 170 400 600 380 200 130 300


Production Incremental Subcontract level cost 130 90 7,200 130 40 3,200 130 270 21,600 130 470 37,600 130 250 20,000 130 70 5,600 130 0 0 130 170 13,600 Total 108,800 33

Aggregate Planning Strategy - Hybrid

Units


rate break

1

2

3


4

5

6 7 8 9 10 11 12 13 Time Periods 34

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


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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


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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.


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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 - 16027304

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MAIN OBJECTIVE


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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 untuk produksi.

: jumlah unit dari kapasitas mesin yang dibutuhkan

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.


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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.


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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.


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ADA PERTANYAAN ?


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

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