Aggregate Planning (PPC)

PPIC Ag Aggr greega gate te Pla P lann nnin ingg Aggregate Planning Chapter 003 www.andresugiyono.edublogs.org JURUSAN TEKNIK IINDUSTR NDUSTRII UNISSULA SEMARANG

04-1

ANDRE SUGIYONO

Learn Lea rnin ingg Object Objectiv ivees When you complete this chapter, you should be able to : Define: ♦ Identify or Define: ♦ ♦ ♦ ♦

♦

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

Describe or Explain: Explain: ♦ ♦

How to do aggregate planning How service firms develop aggregate plans

JURUSAN TEKNIK IINDUSTR NDUSTRII UNISSULA SEMARANG

04-2

ANDRE SUGIYONO

AGREGAT ?

♦

KAPASITAS PRODUKSI. ♦PERENCANAAN AGREGAT? Prose roses s penetapa tapan tin tingkat kat output/ka tput/kap pasitas prod roduks ksii secara cara kese keseluruh luruha an guna memenuhi tin tingkat kat permi rmintaan taan yan yang diperoleh iperoleh dari peram ramalan dan pesan sanan dengan tujua tujuan meminima inimalkan lkan total total biaya produ roduks ksii. JURUSAN TEKNIK IINDUSTR NDUSTRII UNISSULA SEMARANG

04-3

ANDRE SUGIYONO

FUNGSII PERE FUNGS PERENCANA NCANAA A N AGRE A GREGA GAT T ♦

Menjamin ren rencan cana penjualan jualan dan ren rencan cana prod roduks ksii kon konsisten sisten terha terhadap ren rencan cana strateg strategii perusa rusahaan

♦

Alat ukur kur performa rformansi prose roses s peren rencanaan produksi

♦

Menjamin kem kemampuan produ roduksi ksi kon konsisten terhad terhadap renca rencan na produ roduksi ksi


04-4

ANDRE SUGIYONO

FUNGSII PERENC FUNGS PERENCA A NA NAA AN AGREGAT ♦

Memonito itor hasil prod roduks ksii actua ctual terha terhadap ren rencan cana produ roduksi ksi dan membuat penyesu yesua aian

♦

Mengatur persed rsediaan iaan prod roduk jadi jadi untuk mencap capai target arget dan dan membu embuat at peny penyes esua uaiian

♦

Menga engarah rahka kan n peny penyus usun unan an dan dan pel pelaksa aksana naan an jadw adwal induk duk produ roduksi ksi


04-5

ANDRE SUGIYONO

TUJUAN PERENCANAAN AGREGAT ♦

♦

♦

Mengembangkan perencanaan produksi yang feasible pada tingkat menyeluruh yang akan mencapai keseimbanagan antara permintaan dan suplai dengan memperhatikan biaya minimal dari rencana produksi yang dibuat, walaupun biaya bukan satu-satunya bahan pertimbangan. Sebagai masukan perencana sumber daya sehingga perencanaan sumber daya dikembangkan untuk mendukung perencanaan produksi. Meredam (stabilisasi) produksi dan tenaga kerja terhadap fluktuasi permintaan

JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

04-6

ANDRE SUGIYONO

INPUT AGREGAT PLANNING ♦

♦

♦

Sumber daya yang tersedia sepanjang periode rencana produksi harus diketahui Data permintaan yang berasal dari peramalan dan pesanan harus tersedia Memasukkan kebijakan perusahaan yang berkenaan dengan perencanaan agregat, misalnya perubahan tingkat tenega kerja, dan penentuan kebutuhan sumber daya


04-7

ANDRE SUGIYONO

Aggregate 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


04-8

ANDRE SUGIYONO

Planning ♦

Setting goals & objectives ♦

♦

Determining steps to achieve goals ♦

♦

Example: Hire more workers

Setting start & completion dates ♦

♦

Example: Meet demand within the limits of available resources at the least cost

Example: Begin hiring in Jan.; finish, Mar.

Assigning responsibility


04-9

ANDRE SUGIYONO

Planning Tasks and Responsibilities


04-10

ANDRE SUGIYONO

Planning Horizons Short-range plans Job assignments Ordering Job scheduling Dispatching Responsible: Operations managers, supervisors, foremen

Today

Responsible: Operations managers

Intermediate-range plans Sales planning Production planning and budgeting Setting emplo yment, inventory, subcontracting levels Analyzing operating plans

3 Months

1 year

Responsible: Top executi ves

Long-range plans R&D New product plans Capital expenses Facility location, expansion

5 years

Planning Horizon JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

04-11

ANDRE SUGIYONO

Relationships of the Aggregate Plan Marketplace and Demand

Demand Forecasts, orders

Product Decisions

Process Planning & Capacity Decisions

Research and Technology

Work Force

Aggregate Plan fo r Production

Raw Materials Available Inventory On Hand External Capacity Subcontractors

Master Production Schedule, and MRP systems

Detailed Work Schedules


04-12

ANDRE SUGIYONO

Exhibit Exhibit14.1 14.1

Process planning

Long range

Strategic capacity planning

Intermediate Forecasting & demand range management

Sales and operations (aggregate) planning Sales plan

Manufacturing

Aggregate operations plan

Services

Master scheduling Material requirements planning

Short range

Weekly workforce and customer scheduling

Order scheduling


Daily workforce and customer scheduling

04-13

ANDRE SUGIYONO

What ’ s Needed for Aggregate Planning 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! ♦


04-14

ANDRE SUGIYONO

Aggregate Planning ♦

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


04-15

ANDRE SUGIYONO

Aggregate Planning Goals ♦

Meet demand

♦

Use capacity efficiently

♦

Meet inventory policy

♦

Minimize cost ♦

Labor

♦

Inventory

♦

Plant & equipment

♦

Subcontract


04-16

ANDRE SUGIYONO

Aggregate Planning Strategies Pure 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


04-17

ANDRE SUGIYONO

Aggregate Planning Strategies Pure Strategies ♦

Demand Options —change demand: ♦

influencing demand

♦

backordering during high demand periods

♦

counterseasonal product mixing


04-18

ANDRE SUGIYONO

The 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 intermediaterange planning period of 3 to 18 months ♦


ANDRE SUGIYONO

Balancing Aggregate Demand and Aggregate Production Capacity 10000

Suppose Supposethe thefigure figureto to the right represents the right represents forecast forecastdemand demandin in units units Now Nowsuppose supposethis this lower lowerfigure figurerepresents represents the aggregate the aggregatecapacity capacity of the company of the companyto tomeet meet demand demand

10000 8000 8000 6000

7000 6000

5500 4500

4000 2000 0 Jan

Feb

Mar

Apr

May

Jun

9000

10000

8000

8000

What Whatwe wewant wantto todo doisis balance balanceout outthe the production rate, production rate, workforce workforcelevels, levels,and and inventory to make inventory to make these thesefigures figuresmatch matchup up JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

6000 6000

4500

4000

Jan

Feb

4000

4000 2000 0 Mar

Apr

ANDRE SUGIYONO

May

Jun

Required Inputs to the Production Planning System Competitors’ behavior Externa l capacity

Raw material availability Planning for production

Current Current physical workforce capacit y JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

Inventory levels

Market demand

External to firm

Economic conditions

Activities required for ANDRE SUGIYONO productio n

Internal to firm

Aggregate Scheduling Options Advantages and Disadvantages Option

Advantage

Disadvantage

Changing inventory levels

Changes in human resources are gradual, not abrupt production changes

Varying workforce size by hiring or layoffs

Avoids use of Hiring, layoff, other alternatives and training costs


Inventory holding costs; Shortages may result in lost sales

04-22

Some Comments Applies mainly to production, not service, operations

Used where size of labor pool is large

ANDRE SUGIYONO

Advantages/Disadvantages Continued Option

Advantage

Disadvantage Some Comments

Varying production rates through overtime or idle time

Matches seasonal fluctuations without hiring/training costs Permits flexibility and smoothing of the firm's output

Overtime premiums, tired workers, may not meet demand

Allows flexibility within the aggregate plan

Loss of quality control; reduced profits; loss of future business

Applies mainly in production settings

Subcontracting


04-23

ANDRE SUGIYONO

Advantages/Disadvantages Continued Option

Advantage

Disadvantage

Some Comments

Using part-time workers

Less costly and more flexible than full-time workers

Good for unskilled jobs in areas with large temporary labor pools

Influencing demand

Tries to use excess capacity. Discounts draw new customers.

High turnover/training costs; quality suffers; scheduling difficult Uncertainty in demand. Hard to match demand to supply exactly.


04-24

Creates marketing ideas. Overbooking used in some businesses.

ANDRE SUGIYONO

Advantage/Disadvantage Continued Option

Advantage

Back ordering during highdemand periods

May avoid Customer must overtime. Keeps be willing to capacity constant wait, but goodwill is lost.

Many companies backorder.

Counterseasonal Fully utilizes May require products and resources; allows skills or service mixing stable workforce. equipment outside a firm's areas of expertise.

Risky finding products or services with opposite demand patterns.


Disadvantage

04-25

Some Comments

ANDRE SUGIYONO

STRATEGI DAN TEKNIK PERENCANAAN PRODUKSI ♦

STRATEGI MURNI

♦

STRATEGI CAMPURAN


04-26

ANDRE SUGIYONO

STRATEGI MURNI Strategi murni adalah strategi dengan melakukan perubahan pada salah satu factor yang tersebut diatas, yang meliputi : 1.Mengendalikan jumlah inventori 2.Mengendalikan jumlah tenaga kerja 3.Subkontrak 4.Mempengaruhi permintaan ♦


04-27

ANDRE SUGIYONO

STRATEGI CAMPURAN

♦

Strategi ini merupakan penggunaan dua atau lebih strategi murni untuk menghasilkan perencanaan produksi yang feasible.


04-28

ANDRE SUGIYONO

METODE PERENCANAAN PRODUKSI ♦

LEVEL METHOD

♦

LEVEL METHOD WITH OVERTIME

♦

CHASE STRATEGY

♦

LINIER PROGRAMMING

♦

COMPROMISE STRATEGY


04-29

ANDRE SUGIYONO

The Extremes

Level Strategy

Chase Strategy

Production rate is constant

Production equals demand


04-30

ANDRE SUGIYONO

Aggregate Planning Strategies ♦

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


04-31

ANDRE SUGIYONO

Key Strategies for Meeting Demand ♦

Chase

♦

Level

♦

Some combination of the two


ANDRE SUGIYONO

LEVEL METHOD

♦

Metode ini menghitung jumlah tenaga kerja yang dibutuhkan berdasarkan permintaan dan inventori yang ada. Dengan inventori tetap setiap periodenya. Tenaga kerja yang ada harus dapat memenuhi kebutuhan permintaan total selama satu tahun. Dan diasumsikan tidak ada overtime.


04-33

ANDRE SUGIYONO

LEVEL METHOD WITH OVERTIME

♦

Perhitungan yang dilakukan sama seperti level work force, hanya diasumsikan adanya overtime. ♦

CHASE STRATEGY

Pada strategi ini adanya kebutuhan tenaga kerja yang bervariansi setiap periode berdasarkan permintaan yang harus dipenuhi. Dan adanya inventori yang besarnya sama tiap periodenya. JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

04-34

ANDRE SUGIYONO

LINIER PROGRAMMING

♦

Linier programming digunakan bila produksi yang berjalan terdiri dari dua macamproduk atau lebih. Karena tidak mungkin diselesaikan dengan metode sebelumnya. Prosedur perhitungan yang dilakukan melalui metode simplek yang biasanya terdapat dalam perhitungan mengenai penelitian operasional.


04-35

ANDRE SUGIYONO

TAHAPAN 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.


04-36

ANDRE SUGIYONO

FORMULA ♦

RENCANA PRODUKSI = (PERMINTAAN TOTALINVENTORI AWAL)+INVENTORI AKHIR

♦

RENCANA PRODUKSI HARIAN = RENCANA PRODUKSI BULANAN / JML HARI KERJA

♦

SIKLUS WAKTU = JAM KERJA YG TERSEDIA PERHARI / PRODUKSI HARIAN


04-37

ANDRE SUGIYONO

LEVEL 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 SUGIYONO JURUSAN TEKNIK INDUSTRI

♦

UNISSULA SEMARANG

04-38

CHASE STRATEGY ♦

MEMPERTAHANKAN TINGKAT KESTABILAN INVENTORY

♦

PRODUKSI BERVARIASI MENGIKUTI PERMINTAAN TOTAL

♦

RENCANA PRODUKSI = PERMINTAAN TOTAL


04-39

ANDRE SUGIYONO

COMPROMISE 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 ♦


04-40

ANDRE SUGIYONO

Aggregate Planning Examples: Unit Demand and Cost Data Suppose Supposewe wehave havethe thefollowing followingunit unit demand demandand andcost costinformation: information: Demand/mo

Jan

Feb

Mar

Apr

May

Jun

4500

5500

7000

10000

8000

6000

Materials Holding costs Marginal cost of stockout Hiring and training cost Layoff costs Labor hours required Straight time labor cost Beginning inventory Productive hours/worker/day Paid straight hrs/day JURUSAN TEKNIK INDUSTR I UNISSULA SEMARANG Workforce

$5/unit $1/unit per mo. $1.25/unit per mo. $200/worker $250/worker .15 hrs/unit $8/hour 250 units 7.25 8 ANDRE SUGIYONO 200 people

Cut-and-Try Example: Determining Straight Labor Costs and Output Given Giventhe thedemand demandand andcost costinformation informationbelow, below,what what are the aggregate hours/worker/month, units/worker, are the aggregate hours/worker/month, units/worker,and and dollars/worker? dollars/worker? Demand/mo

Jan

Feb

Mar

Apr

May

Jun

4500

5500

7000

10000

8000

6000

Productive hours/worker/day Paid straight hrs/day

22x8hrsx$8=$14 08Days/mo

Feb

M ar

Apr

M ay

Jun

22

19

21

21

22

20

159.5

Units/w orker

23.98


7.25x0.15=1.09 & 1.09x22=23.98

Jan

Hrs/w orker/mo $/w orker

7.25 8

7.25x2 2

$1,408

04-42

ANDRE SUGIYONO

Chase Strategy (Hiring & Firing to meet demand) Jan Days/mo

22

Hrs/w orker/mo

159.5

Units/w orker

23.98

$/w orker

Demand

4,500

Beg. inv.

250

Net req.

4,250 177.23

Hired Fired W orkforce EndinJURUSAN ginvento ry INDUSTRI TEKNIK UNISSULA SEMARANG

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

$1,408

Jan

Req. w orkers

Lets Letsassume assumeour ourcurrent currentworkforce workforceisis77workers. workers.

22 200 0

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

Below Beloware arethe thecomplete completecalculations calculationsfor forthe theremaining remaining months monthsin inthe thesix sixmonth monthplanning planninghorizon horizon Jan

Feb

M ar

Apr

M ay

Jun

22

19

21

21

22

20

Jan

Feb

M ar

Apr

M ay

Jun

Demand

4,500

5,500

7,000

10,000

8,000

6,000

Beg. inv.

250

200

200

200

200

200

200

0

0

0

0

0

0

Days/mo Hrs/w orker/mo

159.5

Units/w orker $/w orker

24 $1,408

Net req. Req. w orkers

4,250 177.23

Hired Fired W orkforce Endinginventory JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

22

ANDRE SUGIYONO

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

Jan 4,500

Feb 5,500

Mar 7,000

Apr 10,000

May 8,000

Jun 6,000

Beg. inv. Net req.

250 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

2

1

3 1 7 0

Hired Fired Workforce

3 4

6

7

10

2 8

Ending inventory

0

0

0

0

0

Jan Feb Mar Apr May Jun $21,250.00 $27,500.00 $35,000.00 $50,000.00 $40,000.00 $30,000.00 5,627.59 7,282.76 9,268.97 13,241.38 10,593.10 7,944.83

Material Labor Hiring cost Firing cost

400.00 750.00


200.00

600.00

Costs 203,750.00 53,958.62 1,200.00

500.00 ANDRE SUGIYONO

250.00

1,500.00

$260,408.62

Level Workforce Strategy (Surplus and Shortage Allowed) Lets Letstake takethe thesame sameproblem problem as asbefore beforebut butthis thistime timeuse use the theLevel LevelWorkforce Workforcestrategy strategy This Thistime timewe wewill willseek seekto touse use aaworkforce workforcelevel levelof of66 workers workers

Jan Demand

4,500

Beg. inv.

250

Net req.

4,250

Workers

6

Production

6,380

Ending inventory

2,130

Surplus

2,130

Shortage JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

ANDRE SUGIYONO

Below Beloware arethe thecomplete completecalculations calculationsfor forthe the remaining remainingmonths monthsin inthe thesix six month monthplanning planninghorizon horizon

Demand Beg. inv. Net req. Workers Production Ending inventory Surplus Shortage

Jan 4,500 250 4,250 6 6,380 2,130 2,130

Feb 5,500 2,130 3,370 6 5,510 2,140 2,140

Mar 7,000 2,140 4,860 6 6,090 1,230 1,230

Apr 10,000 1,230 8,770 6 6,090 -2,680

May 8,000 -2,680 10,680 6 6,380 -1,300

Jun 6,000 -1,300 7,300 6 5,800 -1,500

2,680

1,300

1,500

Note, Note, ifif we we recalculate recalculate this this sheet sheet with with 77 workers workers we we would would have have aa surplus surplus JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

ANDRE SUGIYONO

Below Below are are the the complete complete calculations calculations for for the the remaining remaining months months in in the the six six month month planning planning horizon horizon with with the the other other costs costs included included Jan 4,500 250 4,250 6 6,380 2,130 2,130

Jan $8,448 31,900 2,130

Feb 5,500 2,130 3,370 6 5,510 2,140 2,140

Feb $7,296 27,550 2,140

Mar 7,000 10 4,860 6 6,090 1,230 1,230

Mar $8,064 30,450 1,230


Apr 10,000 -910 8,770 6 6,090 -2,680

May 8,000 -3,910 10,680 6 6,380 -1,300

Jun 6,000 -1,620 7,300 6 5,800 -1,500

2,680

1,300

1,500

Apr $8,064 30,450

May $8,448 31,900

Jun $7,680 29,000

3,350

1,625

1,875

Note, Note,total total costs costsunder under this thisstrategy strategy are areless lessthan than Chase Chaseat at $260.408.62 $260.408.62 $48,000.00 181,250.00 5,500.00 6,850.00

$241,600.00 ANDRE SUGIYONO

Labor Material Storage Stockout

The Graphical Approach to Aggregate 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


04-49

ANDRE SUGIYONO

Forecast and Average Forecast Demand 70 y a d g n i k r o w r e p e t a r n o it c u d o r P

60 50

Forecast Demand

Level production using average monthly forecast demand

40 30 20 10 0 Jan

Feb

Mar

Apr

May

Jun

22

18

21

21

22

20


04-50

ANDRE SUGIYONO

Cumulative Demand Graph for Plan 1 7,000 ) 6,000 s ti Reduction of n Cumulative level inventory U ( 5,000 production using d n 4,000 average monthly a forecast m e D3,000 requirements e v it Cumulative forecast 2,000 a l requirements u m1,000 u C Excess inventory

Jan Feb Mar Apr May Jun JURUSAN TEKNIK INDUSTRI UNISSULA SEMARANG

04-51

ANDRE SUGIYONO

Aggregate Planning (PPC)

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