Rahma Rei Sakura, S.T., M.T. NIP. 153112 - dosen.itats.ac.id · Rahma Rei Sakura, S.T., M.T. NIP....
Transcript of Rahma Rei Sakura, S.T., M.T. NIP. 153112 - dosen.itats.ac.id · Rahma Rei Sakura, S.T., M.T. NIP....
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 3
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 4
Introduction
Factory
Warehouse
Food Mart
Retailer
End
Consumer
Aggregate Planning
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 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 - 16027304 7
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.
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 9
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 10
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 12
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 13
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 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 - 16027304 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 - 16027304 17
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 18
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 19
Controllable (Decision) Variable
Inventory
Production rate
Manpower
Capacity : overtime / recruitment / layoff (tenaga kerja /
workforce)
Subcontract
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 20
Relevant Cost
Hiring/layoff cost
Overtime/undertime cost
Inventory carrying cost
Subcontracting incremental cost
Part time labor cost
Backorder cost
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 22
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 23
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 planningdapat dibedakan menjadi:
1. Linear cost relationships (Metode LDR)
2. Non-linear cost relationships (Metode Bowman)
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 25
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 26
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 28
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 29
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)
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 30
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 31
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)
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 32
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 33
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 34
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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 - 16027304 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 - 16027304 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 - 16027304 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 - 16027304 40
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 41
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
MANAJEMEN OPERASIONAL PRODUKSI - 16027304 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.