Aggregate Sales & Ops. Planning

7/30/2019 Aggregate Sales & Ops. Planning

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Tata McGraw

C

HAPTE

R

16

AggregateS

alesand

Operations

Planning


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Chapter 16

Aggregate Sales andOperations Planning


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Sales and Operations Planning

The Aggregate Operations Plan

Examples: Chase and Levelstrategies

OBJECTIVES

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1-4

Process planning

Strategic capacity

planning

Sales and operations

(aggregate) planning

Sales

plan

Aggregate

operations

plan

Supply network

planning

Forecasting and

demand management

Master scheduling

Material requirements

planning

Order scheduling

Vehicle capacity

planning

Vehicle loading

Vehicle dispatching

Warehouse

receipt

planning

Weeklyworkforce

scheduling

Daily workforce

scheduling

Manufacturing Logistics Services

Long

range

Medium

range

Short

range

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Sales and Operations Planning Activities

Long-range planning Greater than one year planning horizon

Usually performed in annual increments

Medium-range planning Six to eighteen months

Usually with weekly, monthly or quarterlyincrements

Short-range planning One day to less than six months

Usually with weekly or daily increments

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The Aggregate Operations Plan

Main purpose: Specify theoptimal 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 to18 months

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Balancing Aggregate Demandand 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 tothe right representsforecast demand inunits

Now suppose thislower figure representsthe aggregate capacityof the company tomeet demand

What we want to do isbalance out theproduction rate,workforce levels, andinventory to makethese figures match up

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Required Inputs to the Production Planning System

Planningfor

production

External

capacity

Competitorsbehavior

Raw materialavailability

Marketdemand

Economic

conditions

Current

physical

capacity

Current

workforce

Inventory

levels

Activities

required

for

production

External

to firm

Internal

to firm

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Key Strategies for Meeting Demand

Chase

Level

Stable workforce

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Aggregate 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/unitStraight time labor cost $8/hour

Beginning inventory 250 units

Productive hours/worker/day 7.25

Paid straight hrs/day 8

Suppose we have the following unit

demand 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 159.5 137.75 152.25 152.25 159.5 145

Units/worker 1063.33 918.33 1015 1015 1063.33 966.67

$/worker $1 ,408 1 ,216 1 ,344 1 ,344 1 ,408 1 ,280

Productive hours/worker/day 7.25

Paid 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, anddollars/worker?

7.25x2

2

7.25x0.15=48.33

&

84.33x22=1063.3322x8hrsx$8=$140

8

Cut-and-Try Example: DeterminingStraight Labor Costs and Output

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Chase Strategy(Hiring & Firing to meet demand)

Jan

Days/mo 22

Hrs/worker/mo 159 .5

Units/wo rke r 1 ,0 63 .3 3

$ /worker $1 ,408

Jan

Demand 4 ,500

Beg. inv. 250

Net req. 4 ,250Req. workers 3 .997

Hired

Fired 3

W orkforce 4

Ending inventory 0

Lets assume our current workforce is 7workers.

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

Then, calculate number of workersneeded to produce the netrequirements, or4250/1063.33=3.997 or 4 workers

Finally, determine the number ofworkers to hire/fire. In this case weonly need 4 workers, we have 7, so3 can be fired.

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Jan Feb Mar Apr May JunDays/mo 22 19 21 21 22 20

Hrs/worker/mo 159.5 137.75 152.25 152.25 159.5 145

Units/worker 1,063 918 1,015 1,015 1,063 967

$/worker $1,408 1,216 1,344 1,344 1,408 1,280


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

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 ,000Beg. 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 1Workforce 4 6 7 10 8 7

Ending inventory 0 0 0 0 0 0

Jan Feb Mar Apr May Jun Costs

M ate rial $ 2 1,2 5 0.0 0 $ 2 7,5 0 0.0 0 $ 3 5,0 0 0.0 0 $ 5 0,0 0 0.0 0 $ 4 0,0 0 0.0 0 $ 3 0,0 0 0.0 0 2 0 3,7 5 0.0 0

Labor 5 ,627.59 7,282.76 9 ,268.97 13 ,241.38 10,593 .10 7 ,944 .83 53,958 .62

Hiring 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 inthe six month planning horizon with the other costs included

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Level Workforce Strategy (Surplus and Shortage Allowed)

Jan

Demand 4,500

Beg. inv. 250

Net req. 4,250

Workers 6

Production 6,380Ending inventory 2,130

Surplus 2,130

Shortage

Lets take the same problem asbefore but this time use theLevel Workforce strategy

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 6,000

Beg. 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 5,800

Ending 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 workers

we would have a surplus

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

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

250 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 1,230

2,680 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 29,000 181,250.00

2,130 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 planning

horizon with the other costs included

Note, totalcosts underthis strategy

are less thanChase at$260.408.62

Labor

Material

Storage

Stockout

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Question Bowl

Sales and Operations Planning

activities are usually conductedduring which planning timehorizon?

a. Long-rangeb. Intermediate-rangec. Short-range

d. Really short-rangee. None of the above

Answer: b. Intermediate-range (i.e., 6 to

18 months)

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Question Bowl

Which of the following are

Production Planning Strategiescan involve trade-offs among theworkforce size, work hours,inventory, and backlogs?

a. Chase strategyb. Stable workforce-variable work

hours

c. Level strategyd. All of the abovee. None of the above

Answer: d. All of the above

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Question Bowl

Which of the following are consideredrelevant costs in the Aggregate

Production Plan?a. Costs associated with changes in

the production rateb. Inventory holding costsc. Backordering costs

d. Basic production costse. All of the above

Answer: e. All of the above

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Question Bowl

Which of the following AggregatePlanning Techniques can beperformed using simplespreadsheets?

a. Cut-and-tryb. Linear programmingc. Transportation methodd. All of the above

e. None of the above

Answer: a. Cut-and-try (The other two involve more

complex computational effort than simple

spreadsheets.)

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End of Chapter 16

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Aggregate Sales & Ops. Planning