Aggregate Planning (PPC)

8/7/2019 Aggregate Planning (PPC)

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JURUSAN TEKNIK INDUSTRI

UNISSULA SEMARANG

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


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ANDRE SUGIYONO04-3

AGREGAT ?

KAPASITAS PRODUKSI.

PERENCANAAN AGREGAT?

Prosespenetapan tingkat output/kapasitasproduksi secara

keseluruhangunamemenuhi tingkat permintaanyang diperolehdari peramalandanpesanandengan tujuanmeminimalkan totalbiayaproduksi.


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FUNGSI PERENCANAAN AGREGATFUNGSI PERENCANAAN AGREGAT

Menjamin rencanapenjualandanrencanaproduksikonsisten terhadaprencanastrategi perusahaan

Alat ukur performansi prosesperencanaan

produksi

Menjaminkemampuanproduksi konsisten

terhadaprencanaproduksi


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Memonitor hasil produksi actual terhadaprencanaproduksi danmembuat penyesuaian

Mengatur persediaanproduk jadi untukmencapai

target danmembuat penyesuaian

Mengarahkanpenyusunandanpelaksanaanjadwal

indukproduksi

FUNGSI PERENCANAANFUNGSI PERENCANAANAGREGATAGREGAT


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TUJUAN PERENCANAAN AGREGATTUJUAN PERENCANAAN AGREGAT

Mengembangkan perencanaan produksi yang feasiblepada tingkat menyeluruh yang akan mencapaikeseimbanagan antara permintaan dan suplai denganmemperhatikan biaya minimal dari rencana produksi

yang dibuat, walaupun biaya bukan satu-satunya bahanpertimbangan.

Sebagai masukan perencana sumber daya sehinggaperencanaan sumber daya dikembangkan untuk

mendukung perencanaan produksi. Meredam (stabilisasi) produksi dan tenaga kerja

terhadap fluktuasi permintaan


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ANDRE SUGIYONO04-7

INPUT AGREGAT PLANNINGINPUT AGREGAT PLANNING

Sumber dayayang tersedia sepanjangperioderencanaproduksi harus diketahui

Data permintaanyang berasal dari peramalandan

pesananharus tersediaMemasukkankebijakanperusahaanyang

berkenaandenganperencanaanagregat,

misalnyaperubahan tingkat tenegakerja, danpenentuankebutuhansumber daya


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ANDRE SUGIYONO04-8

Aggregate Planning RequiresAggregate Planning Requires

Logical overall unit for measuring sales andoutputs

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


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Planning HorizonsPlanning Horizons

Today 3 Months 1 year 5 years

Planning Horizon

Short-range plans

Job assignmentsOrdering

Job scheduling

Dispatching

Intermediate-range plans

Sales planning

Production planning and

budgeting

Setting employment, inventory,subcontracting levels

Analyzing operating plans

Long-range plans

R&D

New product plans

Capital expenses

Facility location, expansion

Responsible:

Operationsmanagers,

supervisors,

foremen

Responsible:

Operations

managers

Responsible:

Top executives


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Relationships of the Aggregate PlanRelationships of the Aggregate Plan

Aggregate

Plan forProduction

Demand

Forecasts,

orders

Master

Production

Schedule, and MRP systems

Detailed Work

Schedules

External

Capacity

Subcontractors

Inventory On

Hand

Raw Materials

Available

Work Force

Marketplace

and Demand

Research and

TechnologyProduct

Decisions

Process

Planning & Capacity

Decisions


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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

Long

range

Intermediate

range

Short

range

Manufacturing

Services

Exhibit 14.1Exhibit 14.1

Sales plan Aggregate operations plan

Forecasting

& demandmanagement


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A mathematically based aggregate planning model requiresconsiderable: time

problem definitionmodel developmentmodel verification

model application expertise

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

specific model

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

WhatWhat s Needed for Aggregates Needed for AggregatePlanningPlanning


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Provides the quantity and timing of production forintermediate 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


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Aggregate Planning StrategiesAggregate Planning StrategiesPure StrategiesPure Strategies

Demand Options change demand:

influencing demand

backordering during high demand periods

counterseasonal product mixing


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The Aggregate Operations PlanThe Aggregate Operations Plan Main purpose: Specify the optimalcombination of

production rate (units completed per unit oftime)

workforce level (number of workers)

inventory on hand (inventory carried fromprevious period)

Product group or broad category(Aggregation)

This planning is done over an intermediate-range planning period of 3 to 18 months


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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 representsforecast demand inunits

Suppose the figure tothe right representsforecast demand inunits

Now suppose thislower figure represents

the aggregate capacityof the company to meetdemand

Now suppose thislower figure represents

the aggregate capacityof the company to meetdemand

What we want to do is

balance out theproduction rate,workforce levels, andinventory to makethese figures match up

What we want to do is

balance out theproduction rate,workforce levels, andinventory to makethese figures match up


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

Planning

for

production

Externa

l

capacity

Competitors

behavior

Raw

material

availability

Market

demand

Economic

conditions

Current

physical

capacit

y

Current

workforce

Inventory

levels

Activities

required

for

productio

n

Externalto firm

Internalto firm


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ANDRE SUGIYONO04-22

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

Option Advantage Disadvantage Some

Comments

Changinginventory levels

Changes inhuman resourcesare gradual, not

abruptproductionchanges

Inventoryholding costs;Shortages may

result in lostsales

Applies mainlyto production,not service,

operations

Varying

workforce sizeby hiring orlayoffs

Avoids use of

other alternatives

Hiring, layoff,

and trainingcosts

Used where size

of labor pool islarge


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CommentsVaryingproduction ratesthrough overtimeor idle time

Matches seasonalfluctuationswithouthiring/training

costs

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/DisadvantagesAdvantages/Disadvantages --ContinuedContinued


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Advantages/DisadvantagesAdvantages/Disadvantages --ContinuedContinued


CommentsUsing part-timeworkers

Less costly andmore flexiblethan full-timeworkers

Highturnover/trainingcosts; qualitysuffers;

schedulingdifficult

Good forunskilled jobs inareas with largetemporary labor

pools

Influencingdemand

Tries to useexcess capacity.Discounts draw

new customers.

Uncertainty indemand. Hard tomatch demand to

supply exactly.

Createsmarketing ideas.Overbooking

used in somebusinesses.


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Advantage/DisadvantageAdvantage/Disadvantage --ContinuedContinued


CommentsBack 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 of

expertise.

Risky findingproducts orservices withopposite demandpatterns.


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STRATEGI DAN TEKNIKSTRATEGI DAN TEKNIK

PERENCANAAN PRODUKSIPERENCANAAN PRODUKSI

STRATEGI MURNISTRATEGI CAMPURAN


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STRATEGI MURNIStrategi murni adalahstrategi denganmelakukanperubahanpadasalahsatu factor yang tersebut diatas,

yang meliputi :1.Mengendalikan jumlahinventori

2.Mengendalikan jumlah tenagakerja

3.Subkontrak4.Mempengaruhi permintaan


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STRATEGI CAMPURANStrategi ini merupakanpenggunaanduaatau lebih

strategi murni untukmenghasilkanperencanaan

produksi yang feasible.


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METODE PERENCANAAN PRODUKSIMETODE PERENCANAAN PRODUKSI

LEVEL METHODLEVEL METHOD WITH OVERTIME

CHASE STRATEGY

LINIER PROGRAMMING

COMPROMISE STRATEGY


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The ExtremesThe Extremes

Level

Strategy

Chase

Strategy

Production

equals

demand

Production rate

is constant


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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


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Key Strategies for Meeting DemandKey Strategies for Meeting Demand

Chase

Level

Some combination of the two


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LEVEL METHODMetode ini menghitung jumlah tenagakerjayang

dibutuhkanberdasarkanpermintaandan inventori yang

ada. Dengan inventori tetapsetiapperiodenya. Tenagakerja yang adaharusdapat memenuhi kebutuhan

permintaan total selamasatu tahun. Dan diasumsikan

tidak adaovertime.


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LEVEL METHOD WITH OVERTIME

Perhitunganyang dilakukansamaseperti level work

force, hanyadiasumsikanadanyaovertime.

CHASE STRATEGYPadastrategi ini adanyakebutuhan tenagakerjayang

bervariansi setiapperiodeberdasarkanpermintaan

yang harusdipenuhi. Dan adanyainventori yangbesarnyasamatiapperiodenya.


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LINIER PROGRAMMINGLinier programming digunakanbilaproduksi yang

berjalan terdiri dari duamacamprodukatau lebih.

Karena tidakmungkin diselesaikandenganmetodesebelumnya. Prosedur perhitunganyang dilakukan

melalui metodesimplekyang biasanyaterdapat dalam

perhitunganmengenai penelitianoperasional.


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TAHAPAN AGREGAT PLANNINGTAHAPAN AGREGAT PLANNING

COLLECTING DATA : SALESFORECAST,ORDERS, ADANYA

BACKORDERS,INVENTORY AWAL

MEMBUAT TABEL INFORMASIMENENTUKAN KAPABILITAS PRODUKSI

MELAKUKAN PARTNERSHIP MEETING YANG

DIHADIRI OLEH SELURUH MANAJER.


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FORMULAFORMULA

RENCANA PRODUKSI = (PERMINTAAN TOTAL-

INVENTORI AWAL)+INVENTORI AKHIR

RENCANA PRODUKSI HARIAN=

RENCANA PRODUKSI BULANAN / JML HARIKERJA

SIKLUS WAKTU=

JAM KERJA YG TERSEDIA PERHARI / PRODUKSIHARIAN


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LEVEL METHODLEVEL METHOD

MEMPUNYAI DISTRIBUSI MERATAMEMPERTAHANKAN TINGKAT KESTABILAN

PRODUKSI SEMENTARA MENGGUNAKAN

INVENTORI YANG BERVARIASI UNTUKMENGAKUMULASI OUTPUT

RENCANA PRODUKSI = PERMINTAAN TOTAL

TAHUNAN / BANYAKNYA PERIODE INVENTORY= (INVENTORI AWAL + PRODUKSI)

PERMINTAAN TOTAL


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CHASE STRATEGYCHASE STRATEGY

MEMPERTAHANKAN TINGKAT KESTABILANINVENTORY

PRODUKSI BERVARIASI MENGIKUTI

PERMINTAAN TOTALRENCANA PRODUKSI = PERMINTAAN TOTAL


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COMPROMISE STRATEGYCOMPROMISE STRATEGY

KOMPROMI ANTARA KEDUA METODEPERENCANAAN PRODUKSI

DITETAPKAN TERLEBIH DAHULU HORISONWAKTU PERENCANAAN PRODUKSI

PRODUKSI DILAKUKAN KETIKA INVENTORY ONHAND HABIS.

RENCANA PRODUKSI = PERMINTAAN TOTAL

TAHUNAN / BANYAKNYA HORISON WAKTUPERENCANAAN


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

Materials $5/unit

Holding costs $1/unit per mo.

Marginal cost of stockout $1.25/unit per mo.Hiring and training cost $200/worker

Layoff costs $250/worker

Labor hours required .15 hrs/unit

Straight time labor cost $8/hourBeginning inventory 250 units

Productive hours/worker/day 7.25

Paid straight hrs/day 8

Workforce 200 people

Suppose we have the following unitdemand and cost information:

Suppose we have the following unitdemand and cost information:

Demand/mo Jan Feb Mar Apr May Jun

4500 5500 7000 10000 8000 6000


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Days/mo 22 19 21 21 22 20

Hrs/worker/mo 159.5

Units/worker 23.98

$/worker $1,408

Productive hours/worker/day 7.25

Paid straight hrs/day 8

Demand/mo Jan Feb Mar Apr May Jun4500 5500 7000 10000 8000 6000

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

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

7.25x2

2

7.25x0.15=1.09 &

1.09x22=23.9822x8hrsx$8=$14

08

CutCut--andand--Try Example: DeterminingTry Example: Determining

Straight Labor Costs and OutputStraight Labor Costs and Output


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

Jan

Days/mo 22

Hrs/worker/mo 159.5

Units/worker 23.98

$/worker $1,408

Jan

Demand 4,500

Beg. inv. 250

Net req. 4,250

Req. workers 177.23

Hired

Fired 22

Workforce 200

Ending inventory 0

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

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

Then, calculate number of workersneeded to produce the netrequirements, or 4250/23.98=177.23or 178 workers

Finally, determine the number ofworkers to hire/fire. In this case weonly need 178 workers, we have200, so 22 can be fired.


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Days/mo 22 19 21 21 22 20

Hrs/worker/mo 159.5

Units/worker 24

$/worker $1,408


Demand 4,500 5,500 7,000 10,000 8,000 6,000

Beg. inv. 250

Net req. 4,250

Req. workers 177.23

Hired

Fired 22

Workforce 200 200 200 200 200 200

Ending inventory 0 0 0 0 0 0

Below are the complete calculations for the remainingmonths in the six month planning horizon

Below are the complete calculations for the remainingmonths in the six month planning horizon


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Demand 4,500 5,500 7,000 10,000 8,000 6,000

Beg. inv. 250

Net req. 4,250 5,500 7,000 10,000 8,000 6,000

Req. workers 3.997 5.989 6.897 9.852 7.524 6.207

Hired 2 1 3

Fired 3 2 1

Workforce 4 6 7 10 8 7

Ending inventory 0 0 0 0 0 0

Jan Feb Mar Apr May Jun Costs

Material $21,250.00 $27,500.00 $35,000.00 $50,000.00 $40,000.00 $30,000.00 203,750.00

Labor 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 1,200.00

Firing 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


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

Jan

Demand 4,500

Beg. inv. 250

Net req. 4,250

Workers 6

Production 6,380

Ending inventory 2,130Surplus 2,130

Shortage

Lets take the same problem

as before but this time usethe Level Workforce strategy

Lets take the same problemas before but this time usethe Level Workforce strategy

This time we will seek to usea workforce level of 6workers

This time we will seek to usea workforce level of 6

workers


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Demand 4,500 5,500 7,000 10,000 8,000 6,000Beg. inv. 250 2,130 2,140 1,230 -2,680 -1,300

Net req. 4,250 3,370 4,860 8,770 10,680 7,300

Workers 6 6 6 6 6 6

Production 6,380 5,510 6,090 6,090 6,380 5,800Ending inventory 2,130 2,140 1,230 -2,680 -1,300 -1,500

Surplus 2,130 2,140 1,230

Shortage 2,680 1,300 1,500

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

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

B l th l t l l ti f th


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4,500 5,500 7,000 10,000 8,000 6,000250 2,130 10 -910 -3,910 -1,620

4,250 3,370 4,860 8,770 10,680 7,300

6 6 6 6 6 6

6,380 5,510 6,090 6,090 6,380 5,800

2,130 2,140 1,230 -2,680 -1,300 -1,500

2,130 2,140 1,2302,680 1,300 1,500


$8,448 $7,296 $8,064 $8,064 $8,448 $7,680 $48,000.00

31,900 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

Below are the complete calculations for the

remaining months in the six month planninghorizon with the other costs included

Below are the complete calculations for the

remaining months in the six month planninghorizon with the other costs included

Note, totalcosts underthis strategyare less than

Chase at$260.408.62

Note, totalcosts underthis strategyare less thanChase at$260.408.62

Labor

MaterialStorageStockout


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The Graphical Approach toThe Graphical Approach toAggregate 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


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C m lati e Demand Graph forCumulative Demand Graph for


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Cumulative Demand Graph forCumulative Demand Graph for

Plan 1Plan 1


Cumulative forecast

requirements

Cumulative level

production using

average monthly

forecast

requirements

Reduction ofinventory

Excess inventoryC

umulativeD

emand(Units)

7,000

6,000

5,000

4,000

3,000

2,000

1,000


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Controlling the Cost of Labor inControlling the Cost of Labor inService FirmsService Firms

Seek:

Close control of labor hours to ensure quick responseto 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

Aggregate Planning (PPC)

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