scheduling – day 2. production planning process process planning strategic capacity planning...
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Scheduling – Day 2
Production Planning Process
Process Planning
Strategic Capacity Planning
Aggregate Planning
Master Production Scheduling
Material Requirements Planning
Order Scheduling Weekly Workforce &Customer Scheduling
Daily Workforce &Customer Scheduling
LongRange
MediumRange
ShortRange
Manufacturing Services
Outline
Scheduling Recap Sequencing rules
Single resource Global
Multiple resources
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 All organizations perform scheduling to some extent…some extent…
Sequencing Rules
Determine the order jobs are processed by Determine the order jobs are processed by a resourcea resource
Types of Sequencing Rules
Sequencing jobs at a single resource
Sequencing jobs across multiple resources
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
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
Global Rules
Consider more than current operation
Look at work at other work centers that needs to be completed before the job is done
Types of Sequencing Rules
Sequencing jobs at a single resource
Sequencing jobs across multiple resources
Scheduling Across Multiple Resources
Previous rules considered scheduling (sequencing) jobs at one resource
How can we schedule jobs across multiple resources??
Two resource problems
Suppose you work with a classmate, Kim on all projects
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In each project you do the research, then Kim writes the report
Processing time (you):
Processing time (Kim):
You want to complete all projects asap
What should be the order for the projects?
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
What order should you do the projects in?
• 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
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
• 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
SequenceEnglish
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
• 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
SequenceEnglish
Management
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
• 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
SequenceEnglish
ManagementFinance
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
• 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
SequenceEnglish
ManagementFinance
Marketing
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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1. 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
Processing time (you):
Processing time (Kim):
• 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
SequenceEnglish
ManagementFinance
Marketing
Accounting
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
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YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
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YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
Marketing
Accounting
YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
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YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
Marketing
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YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
Marketing
Accounting
YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
Marketing
Accounting
YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
ManagementFinance
Marketing
Accounting
YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Sequences tasks to minimize makespan
Two resource problemsJohnson’s Rule
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2 6 3 5 1Processing time (you):
Processing time (Kim):
SequenceEnglish
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YouKim
Period 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Idle time
Sequences tasks to minimize makespan
More Than 2 Resources
Optimal methods don’t exist to minimize makespan
Heuristics CDS Heuristic
Sequencing Rules
Local FCFS LCFS SPT LPT EDD
Global SPO CR
Single Resource Multiple Resources
2 resources Johnson’s rule
> 2 resources heuristics
When should you chooseone rule over another??
Guidelines for Selecting a Sequencing Rule
1.1. SPT most useful when shop is highly congestedSPT most useful when shop is highly congested2.2. Use SPO for periods of normal activityUse SPO for periods of normal activity3.3. Use EDD when only small tardiness values can be Use EDD when only small tardiness values can be
toleratedtolerated4.4. Use FCFS when operating at low-capacity levelsUse FCFS when operating at low-capacity levels
Employee Scheduling
Labor is very flexible resourceLabor is very flexible resource Scheduling workforce is Scheduling workforce is
complicated repetitive taskcomplicated repetitive task Heuristics commonly usedHeuristics commonly used
We’ll cover one simple one today…
Employee Scheduling Heuristic
Let Let N = no. of workers availableN = no. of workers availableDDii = demand for workers on day i = demand for workers on day i
1.1. Assign the first N - DAssign the first N - D11 workers day 1 off. workers day 1 off.
Assign the next N - DAssign the next N - D22 workers day 2 off. workers day 2 off.
Continue in a similar manner until all days are scheduled.Continue in a similar manner until all days are scheduled.
2.2. If number of workdays for full time employee < 5, assign If number of workdays for full time employee < 5, assign remaining workdays so consecutive days off are possible.remaining workdays so consecutive days off are possible.• Assign any remaining work to part-time employees.Assign any remaining work to part-time employees.
3.3. If consecutive days off are desired, consider switching If consecutive days off are desired, consider switching schedules among days with the same demand requirements.schedules among days with the same demand requirements.
Example
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor
SmithSmith
SimpsonSimpson
AllenAllen
DickersonDickerson
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor
SmithSmith
SimpsonSimpson
AllenAllen
DickersonDickerson
N = 5
D1 = D2 = D3 = D4 = D5 = D6 = D7 =
N – D1 = 5 – 3 = 2
XX = day working = day working
OO = day off = day off 1.1. Assign the first N - DAssign the first N - D11 workers day 1 off. workers day 1 off.
Assign the next N - DAssign the next N - D22 workers day 2 off. workers day 2 off.
Continue in a similar manner until all days are have been scheduled.Continue in a similar manner until all days are have been scheduled.
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor OO XX XX OO XX XX XX
SmithSmith OO XX XX OO XX XX XX
SimpsonSimpson XX OO XX XX OO XX XX
AllenAllen XX OO XX XX XX XX OO
DickersonDickerson XX XX OO XX XX XX OO
1.1. Assign the first N - DAssign the first N - D11 workers day 1 off. workers day 1 off.
Assign the next N - DAssign the next N - D22 workers day 2 off. workers day 2 off.
Continue in a similar manner until all days are have been scheduled.Continue in a similar manner until all days are have been scheduled.
N – D2 = 5 – 3 = 2
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor OO XX XX OO XX XX XX
SmithSmith OO XX XX OO XX XX XX
SimpsonSimpson XX OO XX XX OO XX XX
AllenAllen XX OO XX XX XX XX OO
DickersonDickerson XX XX OO XX XX XX OO
5
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5
5
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Workdays
2.2. If number of workdays for full time employee < 5, If number of workdays for full time employee < 5,
assign remaining workdays so consecutive days off are possible.assign remaining workdays so consecutive days off are possible.
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor OO XX XX OO XX XX XX
SmithSmith OO XX XX OO XX XX XX
SimpsonSimpson XX OO XX XX OO XX XX
AllenAllen XX OO XX XX XX XX OO
DickersonDickerson XX XX OO XX XX XX OO
3.3. If consecutive days off are desired, consider switching If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.schedules among days with the same demand requirements.
Completed schedule satisfies requirements Completed schedule satisfies requirements but has no consecutive days off.but has no consecutive days off.
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor OO XX XX OO XX XX XX
SmithSmith OO XX XX OO XX XX XX
SimpsonSimpson XX OO XX XX OO XX XX
AllenAllen XX OO XX XX XX XX OO
DickersonDickerson XX XX OO XX XX XX OO
3.3. If consecutive days off are desired, consider switching If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.schedules among days with the same demand requirements.
DAY OF WEEKDAY OF WEEK MM TT WW THTH FF SASA SUSU
MIN NO. OFMIN NO. OFWORKERS REQUIREDWORKERS REQUIRED 33 33 44 33 44 55 33
TaylorTaylor OO OO XX XX XX XX XX
SmithSmith OO OO XX XX XX XX XX
SimpsonSimpson XX XX XX OO OO XX XX
AllenAllen XX XX XX OO XX XX OO
DickersonDickerson XX XX OO XX XX XX OO
The revised schedule satisfies requirements The revised schedule satisfies requirements with consecutive days off for most employees.with consecutive days off for most employees.
3.3. If consecutive days off are desired, consider switching If consecutive days off are desired, consider switching
schedules among days with the same demand requirements.schedules among days with the same demand requirements.