1. Production Scheduling

2. Production Planning Process
Process Planning
Long
Range
Strategic Capacity Planning
Medium
Aggregate Planning
Range
Manufacturing
Services
Master Production Scheduling
Material Requirements Planning
Weekly Workforce &
Order Scheduling
Customer Scheduling
Short
Range
Daily Workforce &
Customer Scheduling

3. Outline Scheduling Recap Sequencing rules Single resource
Global
Multiple resources

4. Scheduling Deals with the timing of operations
Specifies when resources are needed to produce a product or provide a service
Helps us decide what order to perform jobs
All organizations perform scheduling to some extent…

5. Sequencing Rules
Determine the order jobs are processed by a resource

6. Types of Sequencing Rules
Sequencing jobs at a single resource
Sequencing jobs across multiple resources

7. Sequencing Rules (Single Resource)
Local
First Come First Served
Last Come First Served
Shortest Processing Time
Longest Processing Time
Earliest Due Date
Global
Slack Per Remaining Operation
Critical Ratio
Last class

8. Sequencing Rules (Single Resource)
Local
First Come First Served
Last Come First Served
Shortest Processing Time
Longest Processing Time
Earliest Due Date
Global
Slack Per Remaining Operation
Critical Ratio

9. Global Rules Consider more than current operation
Look at work at other work centers that needs to be completed before the job is done

10. Types of Sequencing Rules
Sequencing jobs at a single resource
Sequencing jobs across multiple resources

11. Scheduling Across Multiple Resources
Previous rules considered scheduling (sequencing) jobs at one resource
How can we schedule jobs across multiple resources??

12. What should be the order
Two resource problems
Suppose you work with a classmate, Kim on all projects
In each project you do the research, then Kim writes the report
You want to complete all projects asap
Processing time (you): 2 6 3 5 1
Processing time (Kim): 4 3 5 4 2
What should be the order
for the projects?
Finance
English
Marketing
Accounting
Management

13. Two resource problems Sequences tasks to minimize makespan
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Processing time (you): 2 6 3 5 1
Processing time (Kim): 4 3 5 4 2
What order should you
do the projects in?
Finance
English
Marketing
Accounting
Management

14. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Sequence
English
Processing time (you): 2 6 3 5 1
Processing time (Kim): 4 3 5 4 2
Finance
English
Marketing
Accounting
Management

15. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim): 4 3 5 4 2
Finance
English
Marketing
Accounting
Management

16. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Finance
English
Marketing
Accounting
Management

17. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Finance
English
Marketing
Accounting
Management
Marketing

18. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Find the smallest processing time
If its on the 1st machine, assign the task at the beginning
of the sequence and eliminate it from further consideration
If its on the 2nd machine, assign the task at the end
of the sequence and eliminate it from further consideration
2. Repeat step 1 for all unassigned tasks
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

19. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

20. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

21. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

22. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

23. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

24. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

25. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

26. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

27. Two resource problems Sequences tasks to minimize makespan Sequence
Johnson’s Rule
Sequences tasks to minimize makespan
Idle time
Sequence
English
Processing time (you): 2 6 3 5 1
Management
Processing time (Kim):
Finance 4 3 5 4 2
Accounting
Finance
English
Marketing
Accounting
Management
Marketing

28. Optimal methods don’t exist to minimize makespan
More Than 2 Resources
Optimal methods don’t exist to minimize makespan
Heuristics
CDS Heuristic

29. Sequencing Rules Single Resource Multiple Resources Local Global
FCFS
LCFS
SPT
LPT
EDD
Global
SPO CR
2 resources
Johnson’s rule
> 2 resources
heuristics
When should you choose
one rule over another??

30. Guidelines for Selecting a Sequencing Rule
SPT most useful when shop is highly congested
Use SPO for periods of normal activity
Use EDD when only small tardiness values can be tolerated
Use FCFS when operating at low-capacity levels

31. Employee Scheduling Labor is very flexible resource
Scheduling workforce is complicated repetitive task
Heuristics commonly used
We’ll cover one simple one today…

32. Employee Scheduling Heuristic
Let N = no. of workers available Di = demand for workers on day i
Assign the first N - D1 workers day 1 off.
Assign the next N - D2 workers day 2 off.
Continue in a similar manner until all days are scheduled.
If number of workdays for full time employee < 5, assign remaining workdays so consecutive days off are possible.
Assign any remaining work to part-time employees.
If consecutive days off are desired, consider switching schedules among days with the same demand requirements.

33. Example DAY OF WEEK M T W TH F SA SU MIN NO. OF
WORKERS REQUIRED
Taylor
Smith
Simpson
Allen
Dickerson

34. N = 5 N – D1 = 5 – 3 = 2 DAY OF WEEK M T W TH F SA SU MIN NO. OF
X = day working
O = day off
Assign the first N - D1 workers day 1 off.
Assign the next N - D2 workers day 2 off.
Continue in a similar manner until all days are have been scheduled.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor
Smith
Simpson
Allen
Dickerson
D1 =
D2 =
D3 =
D4 =
D5 =
D6 =
D7 =
N = 5
N – D1 =
5 – 3 = 2

35. N – D2 = 5 – 3 = 2 DAY OF WEEK M T W TH F SA SU MIN NO. OF
Assign the first N - D1 workers day 1 off.
Assign the next N - D2 workers day 2 off.
Continue in a similar manner until all days are have been scheduled.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O X X O X X X
Smith O X X O X X X
Simpson X O X X O X X
Allen X O X X X X O
Dickerson X X O X X X O
N – D2 =
5 – 3 = 2

36. DAY OF WEEK M T W TH F SA SU MIN NO. OF WORKERS REQUIRED 3 3 4 3 4 5 3
If number of workdays for full time employee < 5,
assign remaining workdays so consecutive days off are possible.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O X X O X X X
Smith O X X O X X X
Simpson X O X X O X X
Allen X O X X X X O
Dickerson X X O X X X O
Work
days 5 5 5 5 5

37. If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O X X O X X X
Smith O X X O X X X
Simpson X O X X O X X
Allen X O X X X X O
Dickerson X X O X X X O
Completed schedule satisfies requirements but has no consecutive days off.

38. DAY OF WEEK M T W TH F SA SU MIN NO. OF WORKERS REQUIRED 3 3 4 3 4 5 3
If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O X X O X X X
Smith O X X O X X X
Simpson X O X X O X X
Allen X O X X X X O
Dickerson X X O X X X O

39. If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O O X X X X X
Smith O O X X X X X
Simpson X X X O O X X
Allen X X X O X X O
Dickerson X X O X X X O
The revised schedule satisfies requirements with consecutive days off for most employees.