Operation management 6e by russel and taylor ch14

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Chapter 14
Sales and Operations Planning
Operations
Operations Management
Management -- 66thth Edition
Edition
Roberta Russell & Bernard W. Taylor, III

Copyright 2009 John Wiley & Sons, Inc.

Beni Asllani
University of Tennessee at Chattanooga

Lecture Outline
 The Sales and Operations Planning
Process
 Strategies for Adjusting Capacity
 Strategies for Managing Demand
 Quantitative Techniques for Aggregate
Planning
 Hierarchical Nature of Planning
 Aggregate Planning for Services
Copyright 2009 John Wiley & Sons, Inc.

14-2

Sales and Operations Planning
 Determines the resource capacity needed to
meet demand over an intermediate time

horizon




Aggregate refers to sales and operations planning
for product lines or families
Sales and Operations planning (S&OP) matches
supply and demand

 Objectives




Establish a company wide game plan for allocating
resources
Develop an economic strategy for meeting
demand

Copyright 2009 John Wiley & Sons, Inc.

14-3

Sales and Operations Planning
Process

Copyright 2009 John Wiley & Sons, Inc.

14-4

The Monthly S&OP Planning
Process

Copyright 2009 John Wiley & Sons, Inc.

14-5

Meeting Demand Strategies
 Adjusting capacity




Resources necessary to meet demand
are acquired and maintained over the
time horizon of the plan
Minor variations in demand are handled
with overtime or under-time

 Managing demand


Proactive demand management

Copyright 2009 John Wiley & Sons, Inc.

14-6

Strategies for Adjusting Capacity
 Level production


Producing at a constant rate
and using inventory to
absorb fluctuations in
demand

 Overtime and under-time


 Subcontracting


 Chase demand


Hiring and firing workers to
match demand
Maintaining resources for
high-demand levels

Let outside companies
complete the work

 Part-time workers



 Peak demand


Increasing or decreasing
working hours

Hiring part time workers to
complete the work

 Backordering

Copyright 2009 John Wiley & Sons, Inc.



Providing the service or
product at a later time period

14-7

Level Production
Demand

Units

Production

Time
Copyright 2009 John Wiley & Sons, Inc.

14-8

Chase Demand
Demand

Units

Production

Time
Copyright 2009 John Wiley & Sons, Inc.

14-9

Strategies for Managing Demand
 Shifting demand into
other time periods




Incentives
Sales promotions
Advertising campaigns

 Offering products or
services with countercyclical demand patterns
 Partnering with suppliers
to reduce information
distortion along the
supply chain
Copyright 2009 John Wiley & Sons, Inc.

14-10

Quantitative Techniques For AP






Pure Strategies
Mixed Strategies
Linear Programming
Transportation Method
Other Quantitative
Techniques

Copyright 2009 John Wiley & Sons, Inc.

14-11

Pure Strategies
Example:

QUARTER

SALES FORECAST (LB)

Spring
Summer
Fall
Winter

80,000
50,000
120,000
150,000

Hiring cost = $100 per worker
Firing cost = $500 per worker
Inventory carrying cost = $0.50 pound per quarter
Regular production cost per pound = $2.00
Production per employee = 1,000 pounds per quarter
Beginning work force
= 100 workers
Copyright 2009 John Wiley & Sons, Inc.

14-12

Level Production Strategy

Level production
(50,000 + 120,000 + 150,000 + 80,000)
= 100,000 pounds
4

QUARTER
Spring
Summer
Fall
Winter

SALES
FORECAST
80,000
50,000
120,000
150,000

PRODUCTION
PLAN
INVENTORY
100,000
100,000
100,000
100,000
400,000

20,000
70,000
50,000

0
140,000

Cost of Level Production Strategy
(400,000 X $2.00) + (140,00 X $.50) = $870,000
Copyright 2009 John Wiley & Sons, Inc.

14-13

Chase Demand Strategy
QUARTER

SALES
PRODUCTION WORKERS WORKERS WORKERS
FORECAST PLAN
NEEDED
HIRED
FIRED

Spring
Summer

80,000
50,000

80,000
50,000

80

50

0
0

20
30

Fall
Winter

120,000
150,000

120,000
150,000

120
150

70
30

0
0

100

50

Cost of Chase Demand Strategy
(400,000 X $2.00) + (100 x $100) + (50 x $500) = $835,000

Copyright 2009 John Wiley & Sons, Inc.

14-14

Level Production with Excel

Copyright 2009 John Wiley & Sons, Inc.

14-15

Chase Demand with Excel

Copyright 2009 John Wiley & Sons, Inc.

14-16

Mixed Strategy
 Combination of Level Production and
Chase Demand strategies
 Examples of management policies




no more than x% of the workforce can be
laid off in one quarter
inventory levels cannot exceed x dollars

 Many industries may simply shut down
manufacturing during the low demand
season and schedule employee
vacations during that time
Copyright 2009 John Wiley & Sons, Inc.

14-17

Mixed Strategies with Excel

Copyright 2009 John Wiley & Sons, Inc.

14-18

Mixed Strategies with Excel
(cont.)

Copyright 2009 John Wiley & Sons, Inc.

14-19

General Linear Programming (LP)
Model

 LP gives an optimal solution, but demand
and costs must be linear
 Let






Wt = workforce size for period t
Pt =units produced in period t
It =units in inventory at the end of period t
Ft =number of workers fired for period t
Ht = number of workers hired for period t

Copyright 2009 John Wiley & Sons, Inc.

14-20

LP MODEL
Minimize Z = $100 (H1 + H2 + H3 + H4)
+ $500 (F1 + F2 + F3 + F4)
+ $0.50 (I1 + I2 + I3 + I4)
+ $2 (P1 + P2 + P3 + P4)
Subject to

P1 - I 1

= 80,000

I1 + P2 - I2

= 50,000

I2 + P3 - I3

= 120,000

I3 + P4 - I4

= 150,000

(4)
Production

1000 W1

= P1

(5)

constraints

1000 W2

= P2

(6)

1000 W3

= P3

(7)

1000 W4

=P
14-21 4

(8)

(1)
Demand
(2)
constraints
(3)

Copyright 2009 John Wiley & Sons, Inc.

Setting up the Spreadsheet

Copyright 2009 John Wiley & Sons, Inc.

14-22

The LP Solution

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14-23

Transportation Method
SUBCONTRACT
QUARTER
1
CAPACITY

500
2
500
3
500
4
500

EXPECTED

REGULAR

OVERTIME

DEMAND

CAPACITY

CAPACITY

1500

1200

150

1600

1300

200

3000

1300

200

900

1000

Regular production cost per unit
Overtime production cost per unit
Subcontracting cost per unit

Copyright 2009 John Wiley & Sons, Inc.

100

$20
$25
$28

14-24

Transportation Tableau
PERIOD OF USE
PERIOD OF PRODUCTION

1

Beginning
Inventory
1 Regular

2
0

3

300
600

Overtime
Subcontract
2 Regular