Kuliah 3 - Aggregate Plan

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PERENCANAAN AGREGAT

Kuliah 3

LSiPro – FT Untirta

Muhammad Adha Ilhami


Tujuan Pembelajaran

• Mahasiswa mampu menggunakan teknik

agregasi

• Mahasiswa mampu menyusun Master

Production Schedule (MPS) atau Jadwal Induk

Produksi (JIP).


Pemahaman Dasar

• Bahwa aggregate plan (AP) merupakan tahapperencanaan awal dimana hasilnya adalah MPS (Top Level Production Plan) dan dilakukan oleh Top Level

Business Plan.

• AP memperhatikan kapasitas dan kapabilitasperusahaan.

• Analisa AP dilakukan dalam kelompok produk (product family) dengan unit agregat.

• AP melibatkan pemilihan strategi manufaktur.

• AP berperan dalam sebagai interface antaraperusahaan/sistemmanufaktur dan pasar produknya.


Company Top Level Plan


• Alur informasi

dalam AP.

• Data (input)

dan Hasil

(output) AP.

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Planning Horizon


Aggregate planning: Perencanaan kapasitas jangkamenengah, biasanya dilakukan untuk 2 sampai 12 bulan. AP prinsipnya menyesuaikan kapasitas dan permintaan

Shortrange

Intermediate range

Long range

Now 2 months 1 Year

Overview of Planning Level


• Short-range plans (Detailed plans)– Machine loading

– Job assignments

• Intermediate plans (General levels)– Employment

– Output

• Long-range plans– Long term capacity

– Location / layout

– Product/Process design

Why Aggregate Plan?


• Detil lebih sulit diperoleh untuk waktu yang lebih panjang

• Detil membawa banyak ketidakpastian: agregasi yang dilakukanditujukan mengurangi variabilitas– Permintaan total pakaian lebih sedikit mengandung bias dibandingkan

permintaan kaos, celana, dan kemeja.

• Jika terdapat variabilitas kenapa repot-repot membuat rencanadetil, bagaimanapun juga input akat berubah.– Buat rencana yang fleksibel

– Fleksibilitas dan agregasi biasanya sejalan

Rencana Agregat


Strategi perencanaan dalam tahapan Perencanaan dan

Pengendalian Produksi yang bermuara pada perencanaan

kapasitas yang optimal.

Proses agregasi (aggregation) ialah pengelompokan beberapa

jenis item menjadi product family.

Proses disagregasi (disaggregation) adalah proses derivasi

product family menjadi item.

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Istilah Berkaitan dengan Produk


• Type: kelompok beberapa product families.

• Product family: kelompok beberapa items.

• Item: produk akhir individual yang dibeli (digunakan) oleh konsumen.

• Biasanya hirarki tersebut dimulai dari product family, karena bila sebuah pabrik membuat lebih dari satu jenis type maka operasi perusahaan itu akan menjadi sangat kompleks.

• Pengelompokan sejumlah item ke dalam sebuah product

family dilakukan dengan teknik Group Technology (GT).

Satuan Agregat


• Unit agregat yang biasa

digunakan dalam proses

agregasi :

Jam kerja buruh, mesin atau

resource lainnya.

Waktu standar.

Harga jual, Ongkos produksi.

Satuan agregat dummy

(pseudo product).

Aggregate plan units


• At this level of planning, there is not a lot of detail. Individual end product identity is typically not present. Instead, planning is performed for a composite, or average unit of product in a particular family of similar products. For example, we may plan for units of hair dryers, without regard for whether they are 1500 watt dryers, 1600 watt dryers, 1875 watt dryers, travel dryers, etc.

• Decisions are typically aggregated into monthly time periods. Weekly or daily detail is not needed at this level of decision making. Those finer time breakdowns will be made at lower levels of decision making still to come.

Contoh Proses Agregasi


IBM memproduksi komputer laptop, desktop, notebook dan mesin teknologi tinggi lainnya. Proses agregasi adalah pengelompokkan jenis – jenis komputer tersebut ke dalam family product (misalnya famili komputer).

Sebuah rumah sakit bisa melakukan agregasi jasa yang diberikan menjadi jumlah perawat atau dokter yang dibutuhkan.

PT. Telkomsel bisa melakukan agregasi jumlah unit penjualan kartu prabayar (kartu simpati) dan kartu pascabayar (kartu hallo) menjadi jumlah rupiah penjualan yang diterima. Kartu hallo juga terdiri dari beberapa item.

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Prinsip Aggregate Plan


• Aggregate planning: General plan

– Combined products = aggregate product

• Short and long sleeve shirts = shirt – Single product

– Pooled capacities = aggregated capacity

• Dedicated machine and general machine = machine– Single capacity

– Time periods = time buckets

• Consider all the demand and production of a given month together

– Quite a few time buckets

– When does the demand or production take place in a time bucket?

Aggregate Plan Input


• Sumber daya

– Tenaga Kerja

– Fasilitas

• Ramalan Permintaan

• Statemen KebijakanPerusahaan

– Subkontrak

– Overtime

– Tingkat Persediaan

– Back order

• Biaya

– Biaya inventori

– Biaya back order

– Biaya Hiring/firing

– Biaya Overtime

– Biaya subkontrak

Aggregate Plan Output


• Biaya total Perusahaan

• Projected levels of inventory

– Inventory

– Output

– Employment

– Subcontracting

– Backordering

Strategi Umum AP


• Proactive

– Mengubah demand menyamai kapasitas.

• Reactive

– Mengubah kapasitas menyamai permintaan.

• Mixed

– Gabungan proaktif dan reaktif

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NATURE OF THE AGGREGATE

PLANNING PROBLEM


Time

1 year

Demand Forecast

Regular (or Normal) Capacity Limit

Units of

“Aggregate”

Product

AGGREGATE PLANNING STRATEGIES


Aggregate Planning Strategies

Operations Oriented Marketing Oriented

Leveling strategyChase strategy

Shifting demandCounter seasonal products

Operation Oriented


Strategi untuk mengatasi demand yang berfluktuasi dikategorikan

sebagai strategi berorientasi operasi atau berorientasi market/pasar.

Leveling strategy: Maintain output at a constant (level) rate

throughout the planning horizon. Accommodate seasonal variations

in demand through the accumulation and depletion of inventories.

Chase strategy: Vary the output rate to match the seasonal

variations in demand. Output rate can be varied by (1) hiring and

firing workers, (2) utilizing overtime and idle time, or (3)

subcontracting.

Hybrid strategy: A cost effective aggregate plan may require the use

of a combination of the pure strategies listed above. Such a plan is

referred to as a hybrid plan.

Marketing Oriented


Strategi/taketik marketing berhubungan dengan demand siklis.

Ilustrasi :

Biasanya produksi tertentu (tetap) namun jika demand berada di

bawah produksi,maka marketing harus diandalkan sehingga demand

setara dengan produksi.

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Alur Proses Pengolahan Data –

Peramalan – Rencana Agregat


Item Family Family

Data

Data ProdukA

Data ProdukB

Data ProdukC

PeramalanFamily

PerancanganAgregatFamily

Disagregasi

Disagregasi

Disagregasi

MPS

Agregasi

Agregasi

Agregasi

Data

Data familyA

Data familyB

Data familyC

Peramalan Family

Peramalan Family

Peramalan Family




Disagregasi

Disagregasi

Disagregasi

MPS

Agregasi

Agregasi

Agregasi

Contoh Hasil Peramalan Permintaan

(Dalam agregat)


Month

JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Demand Forecast100 150 250 400 250 50 90 160 260 390 240 60

Additional DataHiring cost: $200 per worker hiredFiring cost: $100 per worker firedRegular pay: $5000 per worker per monthOvertime pay: 1.5 times regular payInventory carrying cost: $10 per unit (based on end of month balances)Backorder cost: $20 per unit (based on end of month shortage)Productivity: 10 units per worker per month (this has also been scaled down from what was originally expressed in thousands of units per month)Beginning workforce size: 20 workers (available at the beginning of January)Beginning inventory: 0 units (no inventory available at the beginning of January)

LEVEL STRATEGY WITH INVENTORY

AND BACKORDERS• Total annual demand = 2,400 units.

• Average monthly production needed = 2,400 units/12 months = 200 units per month.

• Current work force size is 20 workers. This is just enough (because productivity = 10 units per

worker per month).


Month JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Demand Forecast 100 150 250 400 250 50 90 160 260 390 240 60

Production 200 200 200 200 200 200 200 200 200 200 200 200

Beginning Inv. 0 100 150 100 -100 -150 0 110 150 90 -100 -140

Ending Inv. 100 150 100 -100 -150 0 110 150 90 -100 -140 0

Carrying Cost 1000 1500 1000 1100 1500 900

Backorder Cost 2000 3000 2000 2800

Regular Labor Cost 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000 100,000

Overtime Cost

Total Inventory Carrying Cost: $7,000Total Backorder Cost: $9,800Total Hiring Cost 0Total Firing Cost 0Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: 0Total Annual Cost: $1,216,800

LEVEL STRATEGY WITH SUBCONTRACT

• Total annual demand = 2,400 units.



worker per month). Subcontract fee is $30 per unit.


Month JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Demand Forecast 100 150 250 400 250 50 90 160 260 390 240 60

Production 200 200 200 200 200 200 200 200 200 200 200 200

Beginning Inv. 0 100 150 100 -100 -150 0 110 150 90 -100 -140

Ending Inv. 100 150 100 -100 -150 0 110 150 90 -100 -140 0

Carrying Cost 1000 1500 1000 1100 1500 900

Subcontract Cost 3000 4500 3000 4200


Overtime Cost

Total Inventory Carrying Cost: $7,000Total Subcontract Cost: $14,200Total Hiring Cost 0Total Firing Cost 0Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: 0Total Annual Cost: $1,221,200

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CHASE STRATEGY WITH HIRING AND

FIRING• Total annual demand = 2,400 units.



worker per month).


MonthJAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Demand Forecast 100 150 250 400 250 50 90 160 260 390 240 60

Workers Needed 10 15 25 40 25 5 9 16 26 39 24 6

Number Hired 5 10 15 4 7 10 13

Number Fired 10 15 20 15 18

Hiring Cost 1,000 2,000 3,000 800 1,400 2,000 2,600

Firing Cost 1,000 1,500 2,000 1,500 1,800

Labor Cost 50,000 75,000 125,000 200,000 125,000 25,000 45,000 80,000 130,000 195,000 120,000 30,000

Overtime Cost

Total Inventory Carrying Cost: 0Total Backorder Cost: 0Total Hiring Cost $12,800Total Firing Cost $7,800Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: 0Total Annual Cost: $1,220,600

CHASE STRATEGY WITH OVERTIME

AND IDLE TIME• Total annual demand = 2,400 units.



worker per month).


MonthJAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC

Demand Forecast 100 150 250 400 250 50 90 160 260 390 240 60

Capacity * 20 20 20 20 20 20 20 20 20 20 20 20

Capacity Needed * 10 15 25 40 25 5 9 16 26 39 24 6

Overtime * 5 20 5 6 19 4

Idle Time * 10 5 15 11 4 14


Overtime Cost 37,500 150,000 37,500 45,000 142,500 30,000

Total Inventory Carrying Cost: 0Total Backorder Cost: 0Total Hiring Cost 0Total Firing Cost 0Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: $442,500Total Annual Cost: $1,642,500

Pilih Yang Mana?



Total Inventory Carrying Cost: 0Total Backorder Cost: 0Total Hiring Cost $12,800Total Firing Cost $7,800Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: 0Total Annual Cost: $1,220,600

Total Inventory Carrying Cost: 0Total Backorder Cost: 0Total Hiring Cost 0Total Firing Cost 0Total Regular Payroll Cost: $1,200,000Total Overtime Payroll Cost: $442,500Total Annual Cost: $1,642,500

Apa Konsekwensinya?

Level Inventory & Backorder Chase Fired & Hired

Chase Overtime & Idletime


Level Subcontract

Linear Programming


Keterangan:

r : ongkos produksi per unit reg time

P : jumlah unit yang diproduksi reg time

h : ongkos kenaikan per unit produk

At : jumlah unit kenaikan produksi

f : ongkos penurunan per unit produk

Rt : jumlah unit penurunan produksi

v : ongkos produksi per unit overtime

Ot : jumlah unit diproduksi overtime

c : ongkos inventori per unit

Kuliah 3 - Aggregate Plan

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