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SEQUENCING
- PORAS SANCHETI 201051
- DEEPAK MALCHE 200932
Sequencing: Determine the order in which jobs at a work center will be processed.
Requires order for sequencing at all work centers as well as sequencing at individual work centers.
Workstation: An area where one person works, usually with special equipment, on a specialized job.
Job time: Time needed for setup and processing of a job.
Job Flow Time: The length of time a job is in the shop at a particular workstation or work center.
Job Lateness: This is the length of time the job completion date is expected to exceed the date the job was due or promised to a customer.
What is Sequencing..??
Makespan: This is the total time needed to complete
a group of jobs. It is the length of time between the start of
the first job in the group and the completion of the last job in
the group.
Average Number of Jobs: Jobs that are considered in
a shop are considered to be work in process inventory.
Mathematically,
Average Number of Jobs= Total Flow Time / Makespan
PRODUCTION
AND
OPERATIONS MANAGEMENT
FCFS - First Come, First Served: Jobs are processed in
the order in which they arrive at a machine or work center.
SPT-
Shortest Processing Time: Jobs are processed according to p
rocessing time at a machine or work center, shortest job first.
DD -
Due Date: Jobs are processed according to due date, earliest
due date first.
CR -
Critical Ratio: Jobs are processed according to smallest ratio
of time remaining until due date to processing time remaining.
Priority Rules
S/O - Slack
Per Operation: Jobs are processed according to average slack
time (time until due date minus remaining time to process).
Compute by dividing slack time by dividing slack time by
number of remaining operations including the current one.
The set of jobs is known, no new jobs arrive after processing
begins and no jobs are canceled.
Setup time is deterministic
There will be no interruptions in processing such as machine
breakdowns, accidents or worker illnesses.
ASSUMPTIONS TO PRIORITY RULE
S
A. Setup Times
B. Processing Times
C. Changes in the set of jobs.
D. Breakdown Consequences.
FACTORS AFFECTING
SCHEDULING
I. Production capacity is reduced : Orders are delayed.
II. No production: Overhead continues.
III. Cost per unit increases: Quality issues.
IV. Product may be damaged.
V. Safety issues.
1. Injury to employees
2. Injury to customers
Scheduling can hinder or help the Operations Strategy.
An on time delivery of a product or service is only possible if the
Operations Managers is able to do effective scheduling.
An ineffective scheduling would result in inefficient use of resou
rces and possible dissatisfied customers.
Scheduling as an operations strategy can provide an
organization a competitive advantage over its competitors.
Time based competition depends on good scheduling.
OPERATIONS STRATEGY
‘n’ Jobs and 1 Machine.
‘n’ Jobs and 2 Machine.
‘n’ Jobs and 3 Machine.
1 Jobs and ‘m’ Machine.
2 Jobs and ‘m’ Machine.
TYPES OF SEQUENCING
Two Resource Problems
( ‘n’ Jobs and 2 Machines)
Suppose you work with a classmate, Kim on multiple projects.
4 3 5 4 2
2 6 3 5 1
In each project you do the research, and Kim writes the report
Processing time (you):
Processing time (Kim):
You want to complete all projects as soon as possible.
What should be the order
for the projects?
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1
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.
• 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):
Processing time (Kim):
What order should you
do the projects in?
Sequences tasks to minimize makespan
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 51
Processing time (you):
Processing time (Kim):
Sequence
English
Sequences tasks to minimize makespan
Two Resource Problems
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.
• 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
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
Sequence
English
Management
Sequences tasks to minimize makespan
Two Resource Problems
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.
• 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
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
Sequence
English
Management
Finance
Sequences tasks to minimize makespan
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.
• 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
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
Sequence
Marketing
Sequences tasks to minimize makespan
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.
• 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
English
Management
Finance
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
Sequences tasks to minimize makespan
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.
• 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
Management
Finance
Accounting
Marketing
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
Two resource problems
Johnson’s Rule
4 3 5 4 2
2 6 3 5 1Processing time (you):
Processing time (Kim):
You
Kim
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
SEQUENCE
English
Management
Finance
Accounting
Marketing
Two Resource Problems
INDUSTRIAL APPLICATIONS
Automobile Industry
DNA Sequencing
Genome Sequencing
Tyre Manufacturing Industry
Thank You
