Scheduling is a fundamental aspect of industrial engineering that deals with organizing and optimizing the use of resources in a production process. It's essentially creating a detailed plan for when and how tasks should be completed to achieve specific goals

1. Chapter Outline
1. Introduction
2. Scheduling Operations
3. Scheduling in Low-Volume Systems
4. Scheduling Services
5. Operations Strategy
6.0
Scheduling
R a y m e A n a n g P h D , P E n g .

2. •Explain what
scheduling
involves.
•Importance of
good scheduling.
•Compare product
& service
scheduling. • Describe
scheduling needs
in job shop.
• Use the
assignment
method for
loading.
2
Learning
Objectives
• Describe
scheduling needs
in high-volume
systems.
• Describe
scheduling needs
in intermediate-
volume systems.

3. Introduction
Scheduling
• Establishing the
timing of the use of
equipment, facilities
and human activities
in an organization.
• Scheduling occurs in
every organization’s
activities.
• In the decision-
making hierarchy,
scheduling is the
final step in the
transformation
process before
actual output.
• Effective scheduling can yield cost savings,
increases in productivity and other benefits.
• Objectives of scheduling are to achieve trade-
offs among conflicting goals, including efficient
utilization of staff, equipment and facilities,
minimization of customer waiting time,
inventories and process time. 3

4. Scheduling
Hierarchy
• Comparison of
scheduling hierarchy
between
manufacturing and
services industry.

5. Characteristics
• Standardize equipment.
• Standardize activities.
• Identical operations.
• Require automated
equipment for processing
& handling.
• High and uniform output.
Products:
• Autos
• Smartphones
• Radios
• Televisions
• Toys
• Office supplies
Process Industries:
• Petroleum refining
• Sugar refining
• Mining
• Waste treatment
Scheduling in High-
Volume Systems
5
Goals
To obtain a smooth rate of
flow of goods in order to
get a high utilization of labor
and equipment.

6. Characteristics
• Products made to
order.
• Job shop: Systems
with many variations
in many
requirements.
• Loading: The
assignment of jobs to
processing centers.
Gantt Charts:
• Visual aid for loading and scheduling purposes.
• Types: Load Chart & Schedule Chart
• What’s the difference of those?
• Finite loading: Jobs are assigned to work centers taking
into account the work center capacity and job processing
times.
• Infinite loading: Jobs are assigned to work centers without
regard to the capacity of the work center.
Scheduling in Low-
Volume Systems
6

7. Assignment
Method of Linear
Programming
• A linear
programming
model for optimal
assignment of tasks
and resources.
• Objective: To
obtain an optimum
matching of tasks
and resources.
• Hungarian Method: Method of assigning jobs by one-for-
one matching to identify the lowest-cost solution
• *The basic procedure
1. Subtract the lowest number in each row from every number in the
row. Enter the results in new table.
2. Subtract the lowest number in each column from every number in
the column. Enter the results in another table.
3. Draw the minimum number of vertical and horizontal lines
necessary to cover all the zeros in the table. If the number of lines
equals either the number of rows or the number of columns,
proceed to step 6. Otherwise proceed to step 4.
4. If the number of lines drawn is less than the number of rows:
A. Subtract the smallest uncovered number from every uncovered number in the
table.
B. Add the smallest uncovered number to the numbers at intersections of cross-out
lines.
C. Numbers crossed out but not at intersections of cross-out lines carry over to the
next table.
5. Repeat steps 3 & 4 until an optimal table is obtained.
6. Make the assignments. Begin with rows or columns with only one
zero. Match items that have zeros, using only one match for each
row and each column. Eliminate both the row and the column after
the match.

8. Assignment
Method of Linear
Programming
Example 1:
Four jobs are to be
assigned to four
workers.The number
in the table represent
cost associated with
each job-worker
combination.
Solution
1. Subtract the lowest
number in each row
from every number
in the row. Enter the
results in new table.

9. Assignment
Method of Linear
Programming
Solution
2. Subtract the
lowest number in
each row from
every number in
the row. Enter the
results in new
table.

10. Assignment
Method of Linear
Programming
Solution
3. Draw the
minimum number
of vertical and
horizontal lines
necessary to cover
all the zeros in the
table. If the
number of lines
equals either the
number of rows
or the number of
columns, proceed
to step 6.
Otherwise
proceed to step 4.
• There are only three lines crossed out all zeros and the
table has four rows, this is not the optimum. Note that the
smallest uncovered value is 1.

11. Assignment
Method of Linear
Programming
Solution
4. If the number of lines
drawn is less than the
number of rows:
A. Subtract the smallest
uncovered number
from every
uncovered number
in the table.
B. Add the smallest
uncovered number
to the numbers at
intersections of
cross-out lines.
C. Numbers crossed
out but not at
intersections of
cross-out lines carry
over to the next
table.

12. Assignment
Method of Linear
Programming
Solution
5. Repeat steps 3 & 4
until an optimal
table is obtained.
6. Make the
assignments. Begin
with rows or
columns with only
one zero. Match
items that have
zeros, using only
one match for each
row and each
column. Eliminate
both the row and
the column after the
match.

13. Assignment
Method of Linear
Programming
Exercise 1
Use the assignment
method to determine
the best way to
assign workers job.
Given the following
cost information.
Compute the total
cost for your
assignment.
JOB
C
B
A
6
8
5
1
WORKERS
9
7
6
2
3
5
4
3
Solution:

14. Assignment
Method of Linear
Programming
Exercise 2
Assign trucks to
delivery routes so
that total costs are
minimized.
Given the cost data
shown.
What is the total
cost?
ROUTE
E
D
C
B
A
7
8
9
5
4
1
TRUCK
5
3
8
4
6
2
6
4
10
3
7
3
8
5
5
2
5
4
9
4
3
5
6
5
Solution:

15. • Determining the
order in which the
jobs at a work
center will be
processed.
• Sequencing
determine jobs
processed at
various work
centers and at
individual
workstations.
An area where one or
few workers and/or
machines perform
similar work.
Priority Rules
Simple heuristics
used to select the
order in which jobs
will be processed.
Sequencing
What is
workstation?
15

16. Possible Priority
Rules
First Come First
Serve (FCFS)
Jobs are processed in the order in which they
arrive at a machine or work center.
Shortest Processing
Time (SPT)
Jobs are processed according to processing time
at a machine or work center, shortest job first.
Earliest Due Date
(EDD)
Jobs are processed according to due date, earliest
due date first.
Critical Ratio (CR) Jobs are processed according to smallest ratio of
time remaining until due date to processing time
remaining.
Slack per Operation
(S/O)
Jobs are processed according to average slack
time. Compute by dividing slack time by number
of remaining operations, including the current one.
Rush Emergency or preferred customers first.

17. Assumptions
of Priority
Rules
• The set of jobs
• No new jobs arrive after processing
begin.
• No job are cancelled.
• Setup time is independent of processing
sequence.
• Setup time is deterministic.
• Processing time are deterministic rather
than variable.
• There will be no interruptions in
processing such as machine breakdowns,
accidents, or work illness.

18. Job flow time
• The amount of
time from when a
job arrives until it
is finished.
Performance
Measures
18
Job lateness
• The difference
between actual
completion time
and the due date.
Makespan
• Total time needed
to complete a
group of jobs from
the beginning of
the first job to the
completion of the
last job.
Average
number of jobs
• Total flow time /
Makespan

19. Example 2:
Determining Job
Sequences Using
FCFS Rules
Processing times
(including setup
times) and due dates
for six jobs waiting to
be processed at a
work center are given
in Table 1.
Performance
Measures
19
Determine the sequence of jobs, the average
flow time, average tardiness, and average no. of
jobs at the work center for First Come First
Serve (FCFS) rules. Assume jobs arrive in the
order shown.
Due Date
(days from present
time)
ProcessingTime
(days)
Job
7
2
A
16
8
B
4
4
C
17
10
D
15
5
E
18
12
F
Table 1

20. (2) – (3) Days
Tardy
(0 if negative)
(3)
Due
Date
(2)
Flow
Time
(1)
Processing
Time
Job
0
7
2
2
A
0
16
10
8
B
10
4
14
4
C
7
17
24
10
D
14
15
29
5
E
23
18
41
12
F
54
120
41
20
The FCFS sequence is simply A-B-C-D-E-F. The
measures of effectiveness are as follows:
1) Average flow time: 120/6 = 20 days
2) Average tardiness: 54/6 = 9 days
3) The makespan is 41 days. Average number
of jobs at the work center: 120/41 = 2.93
Example 2:
Determining Job
Sequences Using
FCFS Rules
Solution A:
Performance
Measures

21. (2) – (3) Days
Tardy
(0 if negative)
(3)
Due
Date
(2)
Flow
Time
(1)
Processing
Time
Job
0
7
2
2
A
2
4
6
4
C
0
15
11
5
E
3
16
19
8
B
12
17
29
10
D
23
18
41
12
F
40
108
41
21
The SPT sequence is simply A-C-E-B-D-F. The
measures of effectiveness are as follows:
1) Average flow time: 108/6 = 18 days
2) Average tardiness: 40/6 = 6.67 days
3) The makespan is 41 days. Average number
of jobs at the work center: 108/41 = 2.63
Example 2:
Determining Job
Sequences Using
SPT Rules
Solution B:
Performance
Measures

22. The sequence is C-A-E-B-D-F. The measures of
effectiveness are as follows:
1) Average flow time: 110/6 = 18.33 days
2) Average tardiness: 40/6 = 6.33 days
3) The makespan is 41 days. Average number
of jobs at the work center: 110/41 = 2.68
(2) – (3) Days
Tardy
(0 if negative)
(3)
Due
Date
(2)
Flow
Time
(1)
Processing
Time
Job
0
4
4
4
C
0
7
6
2
A
0
15
11
5
E
3
16
19
8
B
12
17
29
10
D
23
18
41
12
F
38
110
41
22
Example 2:
Determining Job
Sequences Using
EDD Rules
Solution C:
Performance
Measures

23. Critical Ratio
Calculation
(3)
Due
Date
Processing
Time
Job
(7-0)/2 = 3.5
7
2
A
(16-0)/8 = 2.0
16
8
B
(4-0)/4 = 1.0 (Lowest)
4
4
C
(17-0)/10 = 1.7
17
10
D
(15-0)/5 = 3.0
15
5
E
(18-0)/12 = 1.5
18
12
F
23
Using CR we find
Example 2:
Determining Job
Sequences Using
CR Rules
Solution D:
Performance
Measures
Critical Ratio
Calculation
(3)
Due
Date
Processing
Time
Job
(7-4)/2 = 1.5
7
2
A
(16-4)/8 = 1.5
16
8
B
-
-
-
C
(17-4)/10 = 1.3
17
10
D
(15-4)/5 = 2.2
15
5
E
(18-4)/12 = 1.17 (Lowest)
18
12
F
At day 4 (Sequence C completed)

24. Critical Ratio
Calculation
(3)
Due
Date
Processing
Time
Job
(7-16)/2 = -4.5 (lowest)
7
2
A
(16-16)/8 = 0.0
16
8
B
-
-
-
C
(17-16)/10 = 0.1
17
10
D
(15-16)/5 = -0.2
15
5
E
-
-
-
F
24
At day 16 (Sequence C & F completed)
Example 2:
Determining Job
Sequences Using
CR Rules
Solution D (cont.):
Performance
Measures
Critical Ratio
Calculation
(3)
Due
Date
Processing
Time
Job
-
-
-
A
(16-18)8 = -0.25
16
8
B
-
-
-
C
(17-18)/10 = -0.10
17
10
D
(15-18)/5 = -0.60 (lowest)
15
5
E
-
-
-
F
At day 18 (Sequence C, F & A completed)

25. Critical Ratio
Calculation
(3)
Due
Date
Processing
Time
Job
-
-
-
A
(16-23)/8 = 0.875 (lowest)
16
8
B
-
-
-
C
(17-23)/10 = -0.60
17
10
D
-
-
-
E
-
-
-
F
25
At day 23 (Sequence C, F, A & E completed)
Example 2:
Determining Job
Sequences Using
CR Rules
Solution D (cont.):
Performance
Measures

26. 26
Example 2:
Determining Job
Sequences Using
CR Rules
Solution D (cont.):
Performance
Measures
The job sequence is simply C-F-A-E-B-D. The
measures of effectiveness are as follows:
1) Average flow time: 133/6 = 22.17 days
2) Average tardiness: 58/6 = 9.67 days
3) The makespan is 41 days. Average number
of jobs at the work center: 133/41 = 3.24
(2) – (3) Days
Tardy
(0 if negative)
(3)
Due
Date
(2)
Flow
Time
(1)
Processing
Time
Job
0
4
4
4
C
0
18
16
12
F
11
7
18
2
A
8
15
23
5
E
15
16
31
8
B
24
17
41
10
D
58
133
41

27. Average
Number of
Jobs at the
Work Center
Average
Tardiness
Average Flow
Time (days)
Rule
2.93
9.00
20.00
FCFS
2.63
6.67
18.00
SPT
2.68
6.33
18.33
EDD
3.24
9.67
22.17
CR
27
Comparison of the four rules
Performance
Measures
• SPT was the best on minimizing flow time
and minimizing average number of jobs.
• CR was the worst in every measures.
• EDD prove superior in average tardiness.
• This results in faster job completion and
potential to generate revenue.

28. Scheduling
Services involved
1. Costumers
2. Workforce
3. Equipment
28
Appointment
Systems
• Control the timing
of customer arrivals
in order to minimize
customer waiting
while achieving a
high degree of
capacity utilization.
Reservation
Systems
• Enable service
systems to formulate
a fairly accurate
estimate of the
demand on the
system for a given
time period.
• Minimize customer
disappointment
generated excessive
waiting or inability
to obtain service

29. Yield Management
• The application of
pricing strategies
to allocate
capacity among
various
categories of
demand.
29
• The basic yield
management
concept is
applicable to
railroads as well
as airlines.
• Yield management
is multidisciplinary
because it blends
elements of
marketing,
operations and
financial
management.

30. Scheduling the
Workforce
• Capacity
management.
• Best when demand
can be predicted
with reasonable
accuracy.
30
• Eg. :Airlines must
schedule flight crews,
aircraft, baggage
handling equipment,
ticket counter, gate
personnel, food
service, cleaning,
maintenance etc.
Scheduling Multiple
Resources
• Coordination is
necessary.
• Eg.: University must
schedule classrooms,
faculty, equipment,
students etc.

31. Operations Strategy
31
• A good scheduling will help operation strategy in every business
organizations.
• The services can be delivered in a timely manner.
• Resources can be used to best advantage and customers will be
satisfied.
• Effective scheduling can reduce costs and increase productivity

32. Q & A Thank you