rahma rei sakura, s.t., m.t. nip. 153112 - dosen.itats.ac.id · rahma rei sakura, s.t., m.t. nip....

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

NIP. 153112

MANAJEMEN OPERASIONAL PRODUKSI - 16027304

1

MANAJEMEN OPERASIONAL PRODUKSI - 16027304 2

AGGREGATE

PLANNING


Master scheduling

Material requirements planning

Order scheduling

Weekly workforce and

customer scheduling

Daily workforce and customer scheduling

Process planning

Strategic capacity planning

Sales and operations (aggregate) planning

Long

range

Intermediate

range

Short

range

Manufacturing

Services

Sales plan Aggregate operations plan

Forecasting

& demand

management


Introduction

Factory

Warehouse

Food Mart

Retailer

End

Consumer

Aggregate Planning


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.


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.


Introduction

Definisi the aggregate planning consists of determining how feasibleproduction alternatives must be employed in each period to satisfy expecteddemand at minimum total production cost. (Kostas N. Dervitsiotis, 1981)

Suatu pernyataan tingkat produksi yang direncanakan dalam bentuk aggregate yangmengintegrasikan 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.


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.


Production Plan(Make To Order)

Product Family : Pumps Date Issued : 12/30/xx

Unit of Measure : Dollars at cost

MONTH JAN FEB MAR APR MAY …

WORKING DAYS PAST DUE 22 21 22 21 23 …

Forecast 568,724 473,681 381,942 624,000 660,000 …

Order Backing 175,423 568,724 473,681 381,942 426,835 328,720 …

Production Plan 623,075 594,753 381,942 624,000 660,000 …

Planned Daily Rate 28,322 28,322 17,361 29,714 28,696 …

Shipping Forecast 623,075 594,753 381,942 624,000 660,000 …

PRODUCTION PLAN


Production Plan(Make To Stock)

Product Family : Valves Date Issued : 6/1/xx

Unit of Measure : Each

MONTH JUNE JULY AUG SEPT OCT …

WORKING DAYS PAST DUE 21 22 23 20 23 …

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 124 124 124 124 109 …

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

PRODUCTION PLAN


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


Strategi Aggregate Planning

2. Demand options

Mempengaruhi demand advertising (periklanan), promosi, personalselling, discount, diskriminasi harga

Backordering

3. Pure strategies

Bila yang diubah-ubah hanya satu variabel

4. Mixed Options

Melibatkan pengubahan beberapa variabel, misalnya bila pure strategytidak feasible


Fase-fase Aggregate Planning

Phase 1Forecast aggregate

demand

Time series with

seasonals

Moving averages

Exponential

smoothing

Others

Phase 2Smooth out capacity

utilization

Complementary

products

Pricing

Promotion

Flexibility delivery

times

Phase 3Determine feasible

production alternative

Fixed work force

- Overtime

- Undertime

Variable work force

- Hiring

- Layoffs

Inventory

Backordering

Subcontracting

Phase 4Allocate demand to

production periods

Linear costs

Trial and Error

Linear Programming

- Transportation

- Simplex

Nonlinear Costs

Linear decision rule

Others

Heuristic and search models

(suitable for all type of costs)

Periodically

Regularly



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



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



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


Aggregate Plan – Managerial Inputs

Supplier capabilities

Storage capacity

Materials availability

Materials

Current machine capacities

Plans for future capacities

Workforce capacities

Current staffing level

Operations

New products

Product design changes

Machine standards

Engineering

Labor-market conditions

Training capacity

Human resources

Aggregate

plan

Customer needs

Demand forecasts

Competition behavior

Distribution and marketing


Aggregate Plan – Outputs

Units or dollars

subcontracted

Size ofWorkforce and

Workforce Adjustment

Productionper month

(in units or $)

InventoryLevels

Aggregate

plan

Units or dollarsof Backlogs,

backorders, or stockout

Reactive Alternatives

Complementary

ProductsCompetitive

Pricing

Aggressive Alternatives


Controllable (Decision) Variable

Inventory

Production rate

Manpower

Capacity : overtime / recruitment / layoff (tenaga kerja /

workforce)

Subcontract


Relevant Cost

Hiring/layoff cost

Overtime/undertime cost

Inventory carrying cost

Subcontracting incremental cost

Part time labor cost

Backorder cost


Aggregate Planing Objectives


Total Cost

tingsubcontrac

ofCost

firing

ofCost

hiring

ofCost

ngbackorderi

ofCost

inventory from

usedunit ofCost

production

overtime units ofCost

production

regular ofCost

periodin

cost Production

t

tCCCTC 21


Total Cost

4 5 6

Production

alternative

Subcontracting

Inventory

Overtime

production

Regular

production

Demand

forecast

Allocation

amount, units

Unit

costs

Total

costs

80

200*

120

300

$12

$1

$8

$5

$960

$400

$960

$1,500

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

5=

70

0

Total Cost at period 5 $3,820

Inte

rna

l ca

pa

city


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 planningdapat dibedakan menjadi:

1. Linear cost relationships (Metode LDR)

2. Non-linear cost relationships (Metode Bowman)


Klasifikasi Metode Aggregate Planning

Aggregate

planning

method

Cost relationships

Linear Nonlinear

Not yielding

optimal plan

A. Trial and error:

▪ Using table

▪ Using graph

C. Heuristic models and

Computer search

models

Yielding optimal

plan

B. Linear programming

▪ Transportation

method

▪ Simplex method

D. Linear decision rule

Dynamic programming


Sistem Aggregate Planning

Aggregate

Planning

Production rate

Work-force size

Desired inventory

Amount of

subcontracting

Performance criteria(Minimize total production cost)

Output

Decision

Allocate demand

to production

periods using

feasible

alternatives

Period-by-period

demand forecasts

Feasible production

alternatives

Cost data on item 2

Initial condition

Input

ConstraintsCapacity limits for

production alternatives


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


Trial and ErrorForecast demand per Kuartal

Kuartal Demand Kumulatif

1 220 220

2 170 390

3 400 790

4 600 1390

5 380 1770

6 200 1970

7 130 2100

8 300 2400

Demand per kuartal

0

200

400

600

800

1 2 3 4 5 6 7 8

Kuartal

Kuantita

s d

em

and


1 2 3 4 5 6 7 8 9 10 11 12 13

Time Periods

Un

its

Business Cycle

Production

Trial and ErrorLevel Strategy (2)


Trial and ErrorLevel Strategy (1)

Adjusted Ongkos

Inventory*) inventory

1 220 300 80 350 17.500

2 170 300 210 480 24.000

3 400 300 110 380 19.000

4 600 300 -190 80 4.000

5 380 300 -270 0 0

6 200 300 -170 100 5.000

7 130 300 0 270 13.500

8 300 300 0 270 13.500

Total 96.500

Kuartal Demand InventoryProduction

Level

*) Initial inventory: 270


1 2 3 4 5 6 7 8 9 10 11 12 13

Time Periods

Un

its

Business Cycle

Production

Trial and ErrorChase Strategy (3)


Trial and ErrorChase Strategy (3)

Kuartal Demand Hiring Layoff Total

1 220 0 0 0

2 170 0 7.500 7.500

3 400 23.000 0 23.000

4 600 20.000 0 20.000

5 380 0 33.000 33.000

6 200 0 27.000 27.000

7 130 0 10.500 10.500

8 300 17.000 0 17.000

Total 138.000

0

200

400

600

800

1 2 3 4 5 6 7 8


Trial and ErrorSubcontract Strategy

1 220 130 90 7,200

2 170 130 40 3,200

3 400 130 270 21,600

4 600 130 470 37,600

5 380 130 250 20,000

6 200 130 70 5,600

7 130 130 0 0

8 300 130 170 13,600

Total 108,800

Kuartal Demand SubcontractProduction

level

Incremental

cost


Aggregate PlanningStrategy - Hybrid

1 2 3 4 5 6 7 8 9 10 11 12 13

Time Periods

Un

its

Business Cycle

Production

rate break


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


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


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.


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


MAIN OBJECTIVE


a. Production Rate : jumlah unit yang dapat diselesaikan setiap unit waktutertentu. (misal, setiap minggu atau setiap bulan).

b. Workforce : jumlah dari pekerja setiap unit dari kapasitas yangdibutuhkan untuk melakukan produksi.

c. Overtime : jumlah dari waktu lembur perencanaan produksi.

d. Machine Capacity Level : jumlah unit dari kapasitas mesin yang dibutuhkanuntuk produksi.

e. Subcontracting : kebutuhan kapasitas yang disubkontrakkan pada satuperencanaan waktu tertentu.

f. Backlog : permintaan yang tidak dipenuhi, yang muncul padaperiode tertentu tetapi akan dipenuhi pada periode yang akan datang.

g. Backorder : permintaan yang tidak terpenuhi, tetapi pelangganmasih mau menunggu untuk memproduksi barang tersebut.

MAIN OBJECTIVE


h. Safety Stock : jumlah produk yang diproduksi pada satu periode tertentudan digunakan ketika jumlah permintaan lebih besar dari jumlah unit produksi.

i. Inventory : persediaan (stok) dari suatu item atau sumber daya yangdigunakan dalam suatu perusahan.

j. Inventory on Hand : jumlah persediaan yang tidak digunakan dari periodesebelumnya.

k. Shortage / Stock out : jumlah demand > jumlah supply.

MAIN OBJECTIVE


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.

ADA PERTANYAAN ?


rahma rei sakura, s.t., m.t. nip. 153112 - dosen.itats.ac.id · rahma rei sakura, s.t., m.t. nip....

Documents