Bab003 Agregate Planning

JURUSAN TEKNIK INDUSTRIUNISSULA SEMARANG

ANDRE SUGIYONO04-1

PPICPPICAggregate PlanningAggregate Planning

Chapter Chapter 003003www.andresugiyono.edublogs.orgwww.andresugiyono.edublogs.org


ANDRE SUGIYONO04-2

Learning ObjectivesLearning ObjectivesWhen you complete this chapter, you should be

able to :♦ Identify or Define:

♦ Aggregate planning♦ Tactical scheduling♦ Graphic technique for aggregate planning♦ Mathematical techniques for aggregate planning

♦ Describe or Explain:♦ How to do aggregate planning♦ How service firms develop aggregate plans


ANDRE SUGIYONO04-3

♦AGREGAT ?

KAPASITAS PRODUKSI.♦PERENCANAAN AGREGAT?

Proses penetapan tingkat output/kapasitas produksi secarakeseluruhan guna memenuhi tingkat permintaan yang diperolehdari peramalan dan pesanan dengan tujuan meminimalkan total biaya produksi.


ANDRE SUGIYONO04-4

FUNGSI PERENCANAAN AGREGATFUNGSI PERENCANAAN AGREGAT

♦ Menjamin rencana penjualan dan rencana produksikonsisten terhadap rencana strategi perusahaan

♦ Alat ukur performansi proses perencanaanproduksi

♦ Menjamin kemampuan produksi konsistenterhadap rencana produksi


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♦Memonitor hasil produksi actual terhadap rencanaproduksi dan membuat penyesuaian

♦Mengatur persediaan produk jadi untuk mencapaitarget dan membuat penyesuaian

♦Mengarahkan penyusunan dan pelaksanaan jadwalinduk produksi

FUNGSI PERENCANAAN FUNGSI PERENCANAAN AGREGATAGREGAT


ANDRE SUGIYONO04-6

TUJUAN PERENCANAAN AGREGATTUJUAN PERENCANAAN AGREGAT

♦ Mengembangkan perencanaan produksi yang feasible pada tingkat menyeluruh yang akan mencapaikeseimbanagan antara permintaan dan suplai denganmemperhatikan biaya minimal dari rencana produksiyang dibuat, walaupun biaya bukan satu-satunya bahanpertimbangan.

♦ Sebagai masukan perencana sumber daya sehinggaperencanaan sumber daya dikembangkan untukmendukung perencanaan produksi.

♦ Meredam (stabilisasi) produksi dan tenaga kerjaterhadap fluktuasi permintaan


ANDRE SUGIYONO04-7

INPUT AGREGAT PLANNINGINPUT AGREGAT PLANNING

♦Sumber daya yang tersedia sepanjang perioderencana produksi harus diketahui

♦Data permintaan yang berasal dari peramalan danpesanan harus tersedia

♦Memasukkan kebijakan perusahaan yang berkenaan dengan perencanaan agregat, misalnya perubahan tingkat tenega kerja, danpenentuan kebutuhan sumber daya


ANDRE SUGIYONO04-8

Aggregate Planning RequiresAggregate Planning Requires

♦Logical overall unit for measuring sales and outputs

♦Forecast of demand for intermediate planning period in these aggregate units

♦Method for determining costs♦Model that combines forecasts and costs so that

planning decisions can be made


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♦ Setting goals & objectives♦ Example: Meet demand within the limits

of available resources at the least cost♦ Determining steps to achieve goals

♦ Example: Hire more workers♦ Setting start & completion dates

♦ Example: Begin hiring in Jan.; finish, Mar.♦ Assigning responsibility

PlanningPlanning


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Planning Tasks and ResponsibilitiesPlanning Tasks and Responsibilities


ANDRE SUGIYONO04-11

Planning HorizonsPlanning Horizons

Today 3 Months 1 year 5 yearsPlanning Horizon

Short-range plansJob assignmentsOrderingJob schedulingDispatching

Intermediate-range plansSales planningProduction planning and

budgetingSetting employment, inventory,

subcontracting levelsAnalyzing operating plans

Long-range plansR&DNew product plansCapital expensesFacility location, expansion

Responsible: Operations managers, supervisors, foremen

Responsible: Operations managers

Responsible: Top executives


ANDRE SUGIYONO04-12

Relationships of the Aggregate PlanRelationships of the Aggregate Plan

AggregatePlan for

Production

DemandForecasts,

orders

MasterProduction

Schedule, and MRP systems

Detailed WorkSchedules

ExternalCapacity

Subcontractors

Inventory OnHand

Raw MaterialsAvailable

Work Force

Marketplaceand Demand

Research andTechnology

ProductDecisions

ProcessPlanning & Capacity

Decisions


ANDRE SUGIYONO04-13

Master scheduling

Material requirements planning

Order schedulingWeekly workforce andcustomer scheduling

Daily workforce and customer scheduling

Process planning

Strategic capacity planning

Sales and operations (aggregate) planning

Longrange

Intermediaterange

Shortrange

ManufacturingServices

Exhibit 14.1Exhibit 14.1

Sales plan Aggregate operations plan

Forecasting & demand management


ANDRE SUGIYONO04-14

A mathematically based aggregate planning model requires considerable:♦ time

♦ problem definition♦ model development♦ model verification♦ model application

♦ expertise♦ people who understand the problem♦ people who understand both the modeling process, and the

specific model♦ money

♦ money to pay for all of the above♦ often requires funding for several people for several months!

WhatWhat’’s Needed for Aggregate s Needed for Aggregate PlanningPlanning


ANDRE SUGIYONO04-15

♦ Provides the quantity and timing of production for intermediate future♦ Usually 3 to 18 months into future

♦ Combines (‘aggregates’) production♦ Often expressed in common units

♦ Example: Hours, dollars, equivalents (e.g., FTE students)

♦ Involves capacity and demand variables

Aggregate PlanningAggregate Planning


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♦ Meet demand♦ Use capacity efficiently♦ Meet inventory policy♦ Minimize cost

♦ Labor♦ Inventory♦ Plant & equipment♦ Subcontract

Aggregate Planning GoalsAggregate Planning Goals


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Aggregate Planning StrategiesAggregate Planning StrategiesPure StrategiesPure Strategies

♦ Capacity Options — change capacity:♦ changing inventory levels♦ varying work force size by hiring or layoffs♦ varying production capacity through overtime or idle

time♦ subcontracting♦ using part-time workers


ANDRE SUGIYONO04-18

Aggregate Planning StrategiesAggregate Planning StrategiesPure StrategiesPure Strategies

♦ Demand Options — change demand:

♦ influencing demand♦ backordering during high demand periods♦ counterseasonal product mixing


ANDRE SUGIYONO

The Aggregate Operations PlanThe Aggregate Operations Plan♦ Main purpose: Specify the optimal

combination of♦ production rate (units completed per unit of

time)♦ workforce level (number of workers)♦ inventory on hand (inventory carried from

previous period)♦ Product group or broad category

(Aggregation)♦ This planning is done over an intermediate-

range planning period of 3 to 18 months


ANDRE SUGIYONO

Balancing Aggregate DemandBalancing Aggregate Demandand Aggregate Production Capacityand Aggregate Production Capacity

0

2000

4000

6000

8000

10000

Jan Feb Mar Apr May Jun

45005500

7000

10000

8000

6000

0

2000

4000

6000

8000

10000


4500 4000

90008000

4000

6000

Suppose the figure to the right represents forecast demand in units

Suppose the figure to the right represents forecast demand in units

Now suppose this lower figure represents the aggregate capacity of the company to meet demand

Now suppose this lower figure represents the aggregate capacity of the company to meet demand

What we want to do is balance out the production rate, workforce levels, and inventory to make these figures match up

What we want to do is balance out the production rate, workforce levels, and inventory to make these figures match up


ANDRE SUGIYONO

Required Inputs to the Production Planning SystemRequired Inputs to the Production Planning System

Planning for

production

External capacity

Competitors’behavior

Raw material availability

Market demand

Economic conditions

Currentphysical capacity

Current workforce

Inventory levels

Activities required for production

External to firm

Internal to firm


ANDRE SUGIYONO04-22

Aggregate Scheduling Options Aggregate Scheduling Options --Advantages and DisadvantagesAdvantages and Disadvantages

Option Advantage Disadvantage SomeComments

Changinginventory levels

Changes inhuman resourcesare gradual, notabruptproductionchanges

Inventoryholding costs;Shortages mayresult in lostsales

Applies mainlyto production,not service,operations

Varyingworkforce sizeby hiring orlayoffs

Avoids use ofother alternatives

Hiring, layoff,and trainingcosts

Used where sizeof labor pool islarge


ANDRE SUGIYONO04-23


Varyingproduction ratesthrough overtimeor idle time

Matches seasonalfluctuationswithouthiring/trainingcosts

Overtimepremiums, tiredworkers, may notmeet demand

Allowsflexibility withinthe aggregateplan

Subcontracting Permitsflexibility andsmoothing of thefirm's output

Loss of qualitycontrol; reducedprofits; loss offuture business

Applies mainlyin productionsettings

Advantages/Disadvantages Advantages/Disadvantages --ContinuedContinued


ANDRE SUGIYONO04-24

Advantages/Disadvantages Advantages/Disadvantages --ContinuedContinued


Using part-timeworkers

Less costly andmore flexiblethan full-timeworkers

Highturnover/trainingcosts; qualitysuffers;schedulingdifficult

Good forunskilled jobs inareas with largetemporary laborpools

Influencingdemand

Tries to useexcess capacity.Discounts drawnew customers.

Uncertainty indemand. Hard tomatch demand tosupply exactly.

Createsmarketing ideas.Overbookingused in somebusinesses.


ANDRE SUGIYONO04-25

Advantage/Disadvantage Advantage/Disadvantage --ContinuedContinued


Back orderingduring high-demand periods

May avoidovertime. Keepscapacity constant

Customer mustbe willing towait, butgoodwill is lost.

Many companiesbackorder.

Counterseasonalproducts andservice mixing

Fully utilizesresources; allowsstable workforce.

May requireskills orequipmentoutside a firm'sareas ofexpertise.

Risky findingproducts orservices withopposite demandpatterns.


ANDRE SUGIYONO04-26

STRATEGI DAN TEKNIK STRATEGI DAN TEKNIK PERENCANAAN PRODUKSIPERENCANAAN PRODUKSI

♦STRATEGI MURNI♦STRATEGI CAMPURAN


ANDRE SUGIYONO04-27

♦STRATEGI MURNIStrategi murni adalah strategi dengan melakukanperubahan pada salah satu factor yang tersebut diatas, yang meliputi :1.Mengendalikan jumlah inventori2.Mengendalikan jumlah tenaga kerja3.Subkontrak4.Mempengaruhi permintaan


ANDRE SUGIYONO04-28

♦STRATEGI CAMPURANStrategi ini merupakan penggunaan dua atau lebihstrategi murni untuk menghasilkan perencanaanproduksi yang feasible.


ANDRE SUGIYONO04-29

METODE PERENCANAAN PRODUKSIMETODE PERENCANAAN PRODUKSI

♦LEVEL METHOD♦LEVEL METHOD WITH OVERTIME♦CHASE STRATEGY♦LINIER PROGRAMMING♦COMPROMISE STRATEGY


ANDRE SUGIYONO04-30

The ExtremesThe Extremes

Level Strategy

Chase Strategy

Production equals

demand

Production rate is constant


ANDRE SUGIYONO04-31

♦ Mixed strategy♦ Combines 2 or more aggregate scheduling options

♦ Level scheduling strategy♦ Produce same amount every day♦ Keep work force level constant ♦ Vary non-work force capacity or demand options♦ Often results in lowest production costs

Aggregate Planning StrategiesAggregate Planning Strategies


ANDRE SUGIYONO

Key Strategies for Meeting DemandKey Strategies for Meeting Demand

♦Chase

♦Level

♦Some combination of the two


ANDRE SUGIYONO04-33

♦LEVEL METHODMetode ini menghitung jumlah tenaga kerja yang dibutuhkan berdasarkan permintaan dan inventori yang ada. Dengan inventori tetap setiap periodenya. Tenagakerja yang ada harus dapat memenuhi kebutuhanpermintaan total selama satu tahun. Dan diasumsikantidak ada overtime.


ANDRE SUGIYONO04-34

♦LEVEL METHOD WITH OVERTIMEPerhitungan yang dilakukan sama seperti level work force, hanya diasumsikan adanya overtime.♦ CHASE STRATEGYPada strategi ini adanya kebutuhan tenaga kerja yang bervariansi setiap periode berdasarkan permintaanyang harus dipenuhi. Dan adanya inventori yang besarnya sama tiap periodenya.


ANDRE SUGIYONO04-35

♦LINIER PROGRAMMINGLinier programming digunakan bila produksi yang berjalan terdiri dari dua macam produk atau lebih. Karena tidak mungkin diselesaikan dengan metodesebelumnya. Prosedur perhitungan yang dilakukanmelalui metode simplek yang biasanya terdapat dalamperhitungan mengenai penelitian operasional.


ANDRE SUGIYONO04-36

TAHAPAN AGREGAT PLANNINGTAHAPAN AGREGAT PLANNING

♦COLLECTING DATA : SALES FORECAST,ORDERS, ADANYA BACKORDERS,INVENTORY AWAL

♦MEMBUAT TABEL INFORMASI♦MENENTUKAN KAPABILITAS PRODUKSI♦MELAKUKAN PARTNERSHIP MEETING YANG

DIHADIRI OLEH SELURUH MANAJER.


ANDRE SUGIYONO04-37

FORMULAFORMULA

♦RENCANA PRODUKSI = (PERMINTAAN TOTAL-INVENTORI AWAL)+INVENTORI AKHIR

♦RENCANA PRODUKSI HARIAN =RENCANA PRODUKSI BULANAN / JML HARI KERJA

♦SIKLUS WAKTU =JAM KERJA YG TERSEDIA PERHARI / PRODUKSI HARIAN


ANDRE SUGIYONO04-38

LEVEL METHODLEVEL METHOD

♦MEMPUNYAI DISTRIBUSI MERATA♦MEMPERTAHANKAN TINGKAT KESTABILAN

PRODUKSI SEMENTARA MENGGUNAKAN INVENTORI YANG BERVARIASI UNTUK MENGAKUMULASI OUTPUT

♦RENCANA PRODUKSI = PERMINTAAN TOTAL TAHUNAN / BANYAKNYA PERIODE

♦ INVENTORY = (INVENTORI AWAL + PRODUKSI) –PERMINTAAN TOTAL


ANDRE SUGIYONO04-39

CHASE STRATEGYCHASE STRATEGY

♦MEMPERTAHANKAN TINGKAT KESTABILAN INVENTORY

♦PRODUKSI BERVARIASI MENGIKUTI PERMINTAAN TOTAL

♦RENCANA PRODUKSI = PERMINTAAN TOTAL


ANDRE SUGIYONO04-40

COMPROMISE STRATEGYCOMPROMISE STRATEGY

♦KOMPROMI ANTARA KEDUA METODE PERENCANAAN PRODUKSI

♦DITETAPKAN TERLEBIH DAHULU HORISON WAKTU PERENCANAAN PRODUKSI

♦PRODUKSI DILAKUKAN KETIKA INVENTORY ON HAND HABIS.

♦RENCANA PRODUKSI = PERMINTAAN TOTAL TAHUNAN / BANYAKNYA HORISON WAKTU PERENCANAAN


ANDRE SUGIYONO

Aggregate Planning Examples: Unit Demand and Cost DataAggregate Planning Examples: Unit Demand and Cost Data

Materials $5/unitHolding costs $1/unit per mo.Marginal cost of stockout $1.25/unit per mo.Hiring and training cost $200/workerLayoff costs $250/workerLabor hours required .15 hrs/unitStraight time labor cost $8/hourBeginning inventory 250 unitsProductive hours/worker/day 7.25Paid straight hrs/day 8Workforce 200 people

Suppose we have the following unit demand and cost information:

Suppose we have the following unit demand and cost information:

Demand/mo Jan Feb Mar Apr May Jun

4500 5500 7000 10000 8000 6000


ANDRE SUGIYONO04-42

Jan Feb Mar Apr May JunDays/mo 22 19 21 21 22 20Hrs/worker/mo 159.5Units/worker 23.98$/worker $1,408

Productive hours/worker/day 7.25Paid straight hrs/day 8

Demand/mo Jan Feb Mar Apr May Jun

4500 5500 7000 10000 8000 6000

Given the demand and cost information below, whatare the aggregate hours/worker/month, units/worker, and dollars/worker?

Given the demand and cost information below, whatare the aggregate hours/worker/month, units/worker, and dollars/worker?

7.25x22

7.25x0.15=1.09 & 1.09x22=23.9822x8hrsx$8=$14

08

CutCut--andand--Try Example: Determining Try Example: Determining Straight Labor Costs and OutputStraight Labor Costs and Output


ANDRE SUGIYONO

Chase StrategyChase Strategy(Hiring & Firing to meet demand)(Hiring & Firing to meet demand)Jan

Days/mo 22Hrs/worker/mo 159.5Units/worker 23.98$/worker $1,408

JanDemand 4,500Beg. inv. 250Net req. 4,250Req. workers 177.23HiredFired 22Workforce 200Ending inventory 0

Lets assume our current workforce is 7 workers.Lets assume our current workforce is 7 workers.

First, calculate net requirements for production, or 4500-250=4250 units

Then, calculate number of workers needed to produce the net requirements, or 4250/23.98=177.23 or 178 workers

Finally, determine the number of workers to hire/fire. In this case we only need 178 workers, we have 200, so 22 can be fired.


ANDRE SUGIYONO

Jan Feb Mar Apr May JunDays/mo 22 19 21 21 22 20Hrs/worker/mo 159.5Units/worker 24$/worker $1,408

Jan Feb Mar Apr May JunDemand 4,500 5,500 7,000 10,000 8,000 6,000Beg. inv. 250Net req. 4,250Req. workers 177.23HiredFired 22Workforce 200 200 200 200 200 200Ending inventory 0 0 0 0 0 0

Below are the complete calculations for the remaining months in the six month planning horizon

Below are the complete calculations for the remaining months in the six month planning horizon


ANDRE SUGIYONO

Jan Feb Mar Apr May JunDemand 4,500 5,500 7,000 10,000 8,000 6,000Beg. inv. 250Net req. 4,250 5,500 7,000 10,000 8,000 6,000Req. workers 3.997 5.989 6.897 9.852 7.524 6.207Hired 2 1 3Fired 3 2 1Workforce 4 6 7 10 8 7Ending inventory 0 0 0 0 0 0

Jan Feb Mar Apr May Jun CostsMaterial $21,250.00 $27,500.00 $35,000.00 $50,000.00 $40,000.00 $30,000.00 203,750.00Labor 5,627.59 7,282.76 9,268.97 13,241.38 10,593.10 7,944.83 53,958.62Hiring cost 400.00 200.00 600.00 1,200.00Firing cost 750.00 500.00 250.00 1,500.00

$260,408.62

Below are the complete calculations for the remaining months in the six month planning horizon with the other costs included


ANDRE SUGIYONO

Level Workforce Strategy (Surplus and Shortage Allowed)Level Workforce Strategy (Surplus and Shortage Allowed)

JanDemand 4,500Beg. inv. 250Net req. 4,250Workers 6Production 6,380Ending inventory 2,130Surplus 2,130Shortage

Lets take the same problem as before but this time use the Level Workforce strategy

Lets take the same problem as before but this time use the Level Workforce strategy

This time we will seek to use a workforce level of 6 workers

This time we will seek to use a workforce level of 6 workers


ANDRE SUGIYONO

Jan Feb Mar Apr May JunDemand 4,500 5,500 7,000 10,000 8,000 6,000Beg. inv. 250 2,130 2,140 1,230 -2,680 -1,300Net req. 4,250 3,370 4,860 8,770 10,680 7,300Workers 6 6 6 6 6 6Production 6,380 5,510 6,090 6,090 6,380 5,800Ending inventory 2,130 2,140 1,230 -2,680 -1,300 -1,500Surplus 2,130 2,140 1,230Shortage 2,680 1,300 1,500

Note, if we recalculate this sheet with 7 workers we would have a surplusNote, if we recalculate this sheet with 7 workers we would have a surplus

Below are the complete calculations for the remaining months in the six month planning horizonBelow are the complete calculations for the remaining months in the six month planning horizon


ANDRE SUGIYONO

Jan Feb Mar Apr May Jun4,500 5,500 7,000 10,000 8,000 6,000

250 2,130 10 -910 -3,910 -1,6204,250 3,370 4,860 8,770 10,680 7,300

6 6 6 6 6 66,380 5,510 6,090 6,090 6,380 5,8002,130 2,140 1,230 -2,680 -1,300 -1,5002,130 2,140 1,230

2,680 1,300 1,500

Jan Feb Mar Apr May Jun$8,448 $7,296 $8,064 $8,064 $8,448 $7,680 $48,000.0031,900 27,550 30,450 30,450 31,900 29,000 181,250.002,130 2,140 1,230 5,500.00

3,350 1,625 1,875 6,850.00

$241,600.00



Note, total costs under this strategy are less than Chase at $260.408.62

Note, total costs under this strategy are less than Chase at $260.408.62

LaborMaterialStorageStockout


ANDRE SUGIYONO04-49

The Graphical Approach to The Graphical Approach to Aggregate PlanningAggregate Planning

♦ Forecast the demand for each period♦ Determine the capacity for regular time, overtime,

and subcontracting, for each period♦ Determine the labor costs, hiring and firing costs,

and inventory holding costs♦ Consider company policies which may apply to the

workers or to stock levels♦ Develop alternative plans, and examine their total

costs


ANDRE SUGIYONO04-50

Forecast and Average Forecast Forecast and Average Forecast DemandDemand

0

10

20

30

40

50

60

70

Prod

uctio

n ra

te p

er w

orking

day


Forecast Demand

Level production using average monthly forecast demand

22 18 21 21 22 20


ANDRE SUGIYONO04-51

Cumulative Demand Graph for Cumulative Demand Graph for Plan 1Plan 1


Cumulative forecast requirements

Cumulative level production using average monthly

forecast requirements

Reduction of inventory

Excess inventoryCumu

lative

Dem

and (

Units

)7,000

6,000

5,000

4,000

3,000

2,000

1,000


ANDRE SUGIYONO04-52

Controlling the Cost of Labor in Controlling the Cost of Labor in Service FirmsService Firms

Seek:♦ Close control of labor hours to ensure quick response

to customer demand♦ On-call labor resource that can be added or deleted to

meet unexpected demand♦ Flexibility of individual worker skills to permit

reallocation of available labor♦ Flexibility of individual worker in rate of output or hours

of work to meet demand

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Bab003 Agregate Planning