PERT 05 Agregat Planning

� Planning

� Konsep Agregat Planning

� Strategi Agregat Planning

� Metode Agregat Planning

� Agregat Planning di bidang Jasa

� Manajemen Pendapatan

� 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

Planning

Figure 13.1

Planning Horizons

Today 3 Months 1 year 5 years

Planning Horizon

Short-range plans

Job assignments

Ordering

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:

Operations

managers,

supervisors,

foremen

Responsible:

Operations

managers

Responsible:

Top executives

Relationships of the Aggregate Plan

Aggregate

Schedule for

Production

Priority

Planning &

Scheduling

Demand

Forecasts,

orders

Master

Production

ScheduleDetailed Work

Schedules

Plant

Capacity

External

Capacity

Inventory On

Hand

Raw Materials

Available

Work Force

Marketplace

and Demand

Research and

Technology

Product

Decisions

Process

Planning &

Decisions

� 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 Planning

� Meet demand

� Use capacity efficiently

� Meet inventory policy

� Minimize cost– Labor

– Inventory

– Plant & equipment

– Subcontract

Aggregate Planning Goals

Aggregate Planning 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

Aggregate Planning StrategiesPure Strategies

�Demand Options — change demand:

– influencing demand

– backordering during high demand periods

– counterseasonal product mixing

� 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 Strategies

� Graphical & charting techniques

– Popular & easy-to-understand

– Trial & error approach

� Mathematical approaches

– Transportation method

– Linear decision rule

– Management coefficients model

– Simulation

Aggregate Planning Methods

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

Comparison of Aggregate Planning Methods

Charting/graphica

l methods

Transportation

method

Managementcoefficient model

Trial and error

Optimization

Heuristic

Simple to understand, easy

to use. Many solutions; one

chosen may not be optimal

LP software

available;permits sensitivity

analysis and constraints.

Linear function may not be

realistic

Simple, easy to implement;

tries to mimic manager’s

decision process; uses

regression

Techniques Approaches Aspects

Controlling the Cost of Labor in Service 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

1.1. Most services cannot be inventoriedMost services cannot be inventoried

2.2. Demand for services is difficult to predictDemand for services is difficult to predict

3.3. Capacity is also difficult to predictCapacity is also difficult to predict

4.4. Service capacity must be provided at the Service capacity must be provided at the

appropriate place and timeappropriate place and time

5.5. Labor is usually the most constraining Labor is usually the most constraining

resource for servicesresource for services

Aggregate Planning for ServicesAggregate Planning for Services

Yield Management

Yield Management

NONO--SHOWSSHOWS PROBABILITYPROBABILITY PP((NN < < XX))

00 .15.15 .00.00

11 .25.25 .15.15

22 .30.30 .40.40

33 .30.30 .70.70

Optimal probability of noOptimal probability of no--showsshows

P(P(nn < < xx) ) ≤≤≤≤≤≤≤≤ = = .517= = .517CCuu

CCuu

+ + CCoo

7575

75 + 7075 + 70

.517.517

Hotel should be overbooked by two rooms

Yield Management: ExampleYield Management: Example

Operational Management

Agus Prayitno

Planning Horizons

Today 3 Months 1 year 5 years

Planning Horizon

Short-range plans

Job assignments

Ordering

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:

Operations

managers,

supervisors,

foremen

Responsible:

Operations

managers

Responsible:

Top executives

Operational Management

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Developing Aggregate Plan

• Pilih strategi dasar :

– Level, chase, or hybrid

• Tetapkan tingkat produksi (rate):

– Level plan with back orders: rate = rata-rata permintaan sepanjang batas perencanaan, selebihnya menjadi back order.

– Level plan without back orders: rate adalah sejumlah permintaan pada suatu waktu.

– Chase plan: melakukan produksi dengan kerja lembur atau subkontrak dalam memenuhi permintaan.

Operational Management

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Developing the Aggregate Plan

• Hitung jumlah tenaga kerja yang dibutuhkan

• Hitung tingkat persediaan setiap periode,

• Hitung biaya setiap periode dan biaya keseluruhan

• Evaluasi dampak rencana terhadap konsumen dan tenaga kerja.

Operational Management

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Evaluating Alternative Plans

• Level strategy plan

• Chase strategy plan

Operational Management

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Aggregate Planning Example

Period 1 2 3 4 5 6 7

Demand 3000 6000 2000 1500 4000 5500 8500

Beginning Inventory 2500

Beginning Workforce 18

Labor Standard (units/worker) 250

Cost

Costs Per Unit

Regular Time Labor Cost $9.60

Overtime/Subcontracting $14.40

Inventory Holding Cost $5.00

Backorders $7.50

Hiring $500.00

Layoff $750.00

Operational Management

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Level StrategyAggregate Production Planning Cost Total Total

Costs Per Unit Units Cost

Regular Time Labor Cost $9.60 28000 $268,800

Overtime/Subcontracting $14.40 0 $0

Beginning Inventory 2500 Inventory Holding Cost $5.00 25000 $125,000

Beginning Workforce 18 Backorders $7.50 0 $0

Labor Standard (units/worker) 250 Hiring $500.00 0 $0

Layoff $750.00 2 $1,500

Total Costs $395,300

Period 1 2 3 4 5 6 7 8

Demand 3000 6000 2000 1500 4000 5500 8500

Cumulative Demand 3000 9000 11000 12500 16500 22000 30500

Net Cumulative Demand 500 6500 8500 10000 14000 19500 28000

Production/Inventory Planning

Production 4000 4000 4000 4000 4000 4000 4000

Cumulative Production 4000 8000 12000 16000 20000 24000 28000

Inventory (Excess Units) 3500 1500 3500 6000 6000 4500 0

Backorders (Units Short) 0 0 0 0 0 0 0

Capacity Planning

Workers Hired 0 0 0 0 0 0 0

Workers Layed Off 2 0 0 0 0 0 0

Workforce Available 16 16 16 16 16 16 16

Regular Time Capacity (units) 4000 4000 4000 4000 4000 4000 4000

Operational Management

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Non-Financial Criteria

• Operations perspective:

– Smooth & even flow is easy to manage

• Human resources perspective:

– Nobody hired or fired, no overtime or furloughs, so employee morale should be fine

• Marketing perspective:

– All demand met, so no customer service issues

Operational Management

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Chase StrategyAggregate Production Planning Cost Total Total

Costs Per Unit Units Cost

Regular Time Labor Cost $9.60 28000 $268,800

Overtime/Subcontracting $14.40 0 $0

Beginning Inventory 2500 Inventory Holding Cost $5.00 0 $0

Beginning Workforce 18 Backorders $7.50 0 $0

Labor Standard (units/worker) 250 Hiring $500.00 50 $25,000

Layoff $750.00 34 $25,500

Total Costs $319,300

Period 1 2 3 4 5 6 7 8

Demand 3000 6000 2000 1500 4000 5500 8500

Cumulative Demand 3000 9000 11000 12500 16500 22000 30500

Net Cumulative Demand 500 6500 8500 10000 14000 19500 28000

Production/Inventory Planning

Production 500 6000 2000 1500 4000 5500 8500

Cumulative Production 500 6500 8500 10000 14000 19500 28000

Inventory (Excess Units) 0 0 0 0 0 0 0

Backorders (Units Short) 0 0 0 0 0 0 0

Capacity Planning

Workers Hired 0 22 0 0 10 6 12

Workers Layed Off 16 0 16 2 0 0 0

Workforce Available 2 24 8 6 16 22 34

Regular Time Capacity (units) 500 6000 2000 1500 4000 5500 8500

Overtime/Subcontracting (units) 0 0 0 0 0 0 0

Total Production Capacity (units) 500 6000 2000 1500 4000 5500 8500

Operational Management

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Non-Financial Criteria• Operations perspective:

– Can operations ramp up & back down this quickly?

– Much more difficult to accomplish

• Human resources perspective:– Will employees tolerate being hired & fired so rapidly?

– What about training & learning curve issues?

• Marketing perspective:– All demand is met (assuming no strikes)

Operational Management

Agus Prayitno

A Minimum Cost Plan (Hybrid Strategy)

Aggregate Production Planning Cost Total TotalCosts Per Unit Units Cost

Regular Time Labor Cost $9.60 28000 $268,800Overtime/Subcontracting $14.40 0 $0

Beginning Inventory 2500 Inventory Holding Cost $5.00 2750 $13,750Beginning Workforce 18 Backorders $7.50 0 $0Labor Standard (units/worker) 250 Hiring $500.00 28 $14,000

Layoff $750.00 12 $9,000

Total Costs $305,550

Period 1 2 3 4 5 6 7 8

Demand 3000 6000 2000 1500 4000 5500 8500

Cumulative Demand 3000 9000 11000 12500 16500 22000 30500Net Cumulative Demand 500 6500 8500 10000 14000 19500 28000

Production/Inventory Planning

Production 3250 3250 2000 1500 4000 5500 8500

Cumulative Production 3250 6500 8500 10000 14000 19500 28000

Inventory (Excess Units) 2750 0 0 0 0 0 0Backorders (Units Short) 0 0 0 0 0 0 0

Capacity Planning

Workers Hired 0 0 0 0 10 6 12Workers Layed Off 5 0 5 2 0 0 0

Workforce Available 13 13 8 6 16 22 34Regular Time Capacity (units) 3250 3250 2000 1500 4000 5500 8500

Overtime/Subcontracting (units) 0 0 0 0 0 0 0

Total Production Capacity (units) 3250 3250 2000 1500 4000 5500 8500