Scheduling Production Planning Process Planning Long Range Medium

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Scheduling

Scheduling

Production Planning Process Planning Long Range Medium Range Strategic Capacity Planning Aggregate Planning Manufacturing

Production Planning Process Planning Long Range Medium Range Strategic Capacity Planning Aggregate Planning Manufacturing Master Production Scheduling Material Requirements Planning Order Scheduling Short Range How much & when to produce Services How much & when to produce the end item How much & when to produce component items Weekly Workforce & Customer Scheduling Daily Workforce & Customer Scheduling

Outline n Scheduling ü What is it? ü Objectives ü Sequencing rules n Single

Outline n Scheduling ü What is it? ü Objectives ü Sequencing rules n Single resource

Scheduling ü Deals with the timing of operations ü Specifies when resources are needed

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

In service organizations, managers schedule… Nursing staff Operating room use Classroom use Instructor schedules

In service organizations, managers schedule… Nursing staff Operating room use Classroom use Instructor schedules

In manufacturing organizations, managers schedule… Workers Purchases of materials Production of goods … Grinding

In manufacturing organizations, managers schedule… Workers Purchases of materials Production of goods … Grinding Easier to schedule here Sort Forging Lathes Painting Welding Drills Office Milling machines Foundry Wash Dry Harder to schedule here Iron

Sequencing Rules ü Determine the order jobs are processed by a resource üWhich job

Sequencing Rules ü Determine the order jobs are processed by a resource üWhich job should a machine do first, next, etc. ? üWhich surgeries should go to the operating room first? üWhat order should you work on your course projects in? ü Many sequencing rules exist ü Each attempts to achieve to an objective

Objectives in Scheduling ü Meet customer due dates ü Minimize job lateness ü Minimize

Objectives in Scheduling ü Meet customer due dates ü Minimize job lateness ü Minimize response time ü Minimize completion time ü Minimize time in the system ü Minimize overtime ü Maximize machine or labor utilization ü Minimize idle time ü Minimize work-in-process inventory

Types of Sequencing Rules n Sequencing jobs at a single resource n Sequencing jobs

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

Sequencing Rules (Single Resource) n Local ü ü ü - consider only current work

Sequencing Rules (Single Resource) n Local ü ü ü - consider only current work center operation First Come First Served Last Come First Served Shortest Processing Time Longest Processing Time Earliest Due Date n Global - consider current and all subsequent work center operations needed to complete job ü Slack Per Remaining Operation ü Critical Ratio

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

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

Sequencing Example This semester you took 5 classes Each has a major project due

Sequencing Example This semester you took 5 classes Each has a major project due at some point in the semester Projects are assigned during the first week of the semester 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9 On the first Next, day You are given your given an Accounting your English assignment… assignment

Sequencing Example This semester you took 5 classes Each has a major project due

Sequencing Example This semester you took 5 classes Each has a major project due at some point in the semester Projects are assigned during the first week of the semester 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9 What order do you work on the projects?

First Come First Served (FCFS) Jobs are processed in order of arrival Which comes

First Come First Served (FCFS) Jobs are processed in order of arrival Which comes first? 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9 What order do you work on the projects?

First Come First Served (FCFS) 18 6 8 Eng oun anc rke Ma lish

First Come First Served (FCFS) 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) 15 18 6 8 oun anc rke Ma ting

First Come First Served (FCFS) 15 18 6 8 oun anc rke Ma ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Ma 2 6 15 18 6 8 anc e

First Come First Served (FCFS) Ma 2 6 15 18 6 8 anc e 8 ting rke Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Processing time: 9 Ma 8 2 6 15 18

First Come First Served (FCFS) Processing time: 9 Ma 8 2 6 15 18 6 8 ting rke Ma nag em ent Time until due: 23 3

First Come First Served (FCFS) Superimposing due dates… 18 6 8 Eng oun anc

First Come First Served (FCFS) Superimposing due dates… 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Superimposing due dates… So 3 projects are late!! How

First Come First Served (FCFS) Superimposing due dates… So 3 projects are late!! How many weeks late? 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Superimposing due dates… So 3 projects are late!! How

First Come First Served (FCFS) Superimposing due dates… So 3 projects are late!! How many weeks late? 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Total days late = 11 = 2. 2 days

First Come First Served (FCFS) Total days late = 11 = 2. 2 days Number of jobs 5 Avg. job lateness = 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Makespan: total time to process all jobs = 28

First Come First Served (FCFS) Makespan: total time to process all jobs = 28 days Flow time: Sum of times each job spends waiting, and being processed 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Makespan = 28 days + Ma 15 18 6

First Come First Served (FCFS) Makespan = 28 days + Ma 15 18 6 8 Eng oun lish 6 ting 2 e 8 ting rke Ma nag em ent Time until due: 23 + 3 Acc Processing time: 9 16 +19 anc 6 +8 Fin Flow time = 28 = 77

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average flow time = Sum of flow times / # jobs 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average flow time = 77 days/5 jobs 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9 = 15. 4 days/job

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average flow time = 15. 4 days/job Avg # jobs in system = Sum of flow times / total processing time 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average flow time = 15. 4 days/job Avg # jobs in system = 77 days/28 days = 2. 75 Utilization = Total processing time / sum of flow time 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average

First Come First Served (FCFS) Makespan = 28 days Flow time = 77 Average flow time = 15. 4 days/job Avg # jobs in system = 77 days/28 days = 2. 75 Utilization = 28 days/77 days = 36. 4% 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

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

Last Come First Served (LCFS) As jobs pile up the operator picks the on

Last Come First Served (LCFS) As jobs pile up the operator picks the on the top of the stack to work on 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Last Come First Served (LCFS) 18 6 8 Eng oun anc rke Ma lish

Last Come First Served (LCFS) 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Last Come First Served (LCFS) 15 18 6 8 Eng oun Acc anc rke

Last Come First Served (LCFS) 15 18 6 8 Eng oun Acc anc rke Ma lish 6 ting 2 e 8 ting Time until due: 23 3 Fin Processing time: 9

Last Come First Served (LCFS) 15 18 6 8 Eng oun Acc lish 6

Last Come First Served (LCFS) 15 18 6 8 Eng oun Acc lish 6 ting 2 e 8 anc Time until due: 23 3 Fin Processing time: 9

Last Come First Served (LCFS) 6 15 18 6 8 Eng lish 2 ting

Last Come First Served (LCFS) 6 15 18 6 8 Eng lish 2 ting 8 oun Time until due: 23 3 Acc Processing time: 9

Last Come First Served (LCFS) Superimposing due dates… 8 2 6 15 18 6

Last Come First Served (LCFS) Superimposing due dates… 8 2 6 15 18 6 8 lish Time until due: 23 3 Eng Processing time: 9

Last Come First Served (LCFS) Superimposing due dates… So 3 projects are late!! Processing

Last Come First Served (LCFS) Superimposing due dates… So 3 projects are late!! Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Last Come First Served (LCFS) Superimposing due dates… Total days late = 38 =

Last Come First Served (LCFS) Superimposing due dates… Total days late = 38 = 7. 6 days Number of jobs 5 Avg. job lateness = Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Last Come First Served (LCFS) Makespan = 28 days Superimposing due dates… Flow time

Last Come First Served (LCFS) Makespan = 28 days Superimposing due dates… Flow time = 9 + 12 + 20 +22 + 28 = 91 Average flow time = 91 days/5 jobs = 18. 2 days/job Avg # jobs in system = 91 days/28 days = 3. 25 Utilization = 28 days/91 days = 30. 8% Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

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

Shortest Processing Time (SPT) Process the job with the shortest processing time first 18

Shortest Processing Time (SPT) Process the job with the shortest processing time first 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Shortest Processing Time (SPT) 18 6 8 Eng oun anc rke Ma lish 15

Shortest Processing Time (SPT) 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Shortest Processing Time (SPT) Ma 6 15 18 6 8 Eng anc lish 2

Shortest Processing Time (SPT) Ma 6 15 18 6 8 Eng anc lish 2 e 8 ting rke Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Shortest Processing Time (SPT) Ma 6 15 18 6 8 anc lish 2 e

Shortest Processing Time (SPT) Ma 6 15 18 6 8 anc lish 2 e 8 Eng nag em ent Time until due: 23 3 Fin Processing time: 9

Shortest Processing Time (SPT) Ma nag 2 6 15 18 6 8 e 8

Shortest Processing Time (SPT) Ma nag 2 6 15 18 6 8 e 8 anc em ent Time until due: 23 3 Fin Processing time: 9

Shortest Processing Time (SPT) Superimposing due dates… Processing time: 9 Ma nag em ent

Shortest Processing Time (SPT) Superimposing due dates… Processing time: 9 Ma nag em ent Time until due: 23 3 8 2 6 15 18 6 8

Shortest Processing Time (SPT) Superimposing due dates… Total days late = 9 Number of

Shortest Processing Time (SPT) Superimposing due dates… Total days late = 9 Number of jobs 5 Avg. job lateness = Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8 = 1. 8 days

Shortest Processing Time (SPT) Makespan = 28 days Flow time = 2 +5 +

Shortest Processing Time (SPT) Makespan = 28 days Flow time = 2 +5 + 11 + + 28 19 = 65 Average flow time = 65 days/5 jobs = 13 days/job Avg # jobs in system = 65 days/28 days = 2. 32 Utilization = 28 days/65 days = 43. 1% Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

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

Longest Processing Time (LPT) Process the job with the longest processing time first 18

Longest Processing Time (LPT) Process the job with the longest processing time first 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Longest Processing Time (LPT) 18 6 8 Eng oun anc rke Ma lish 15

Longest Processing Time (LPT) 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Longest Processing Time (LPT) 15 18 6 8 Eng oun Acc anc rke Ma

Longest Processing Time (LPT) 15 18 6 8 Eng oun Acc anc rke Ma lish 6 ting 2 e 8 ting Time until due: 23 3 Fin Processing time: 9

Longest Processing Time (LPT) 6 15 18 6 8 Eng oun rke Ma lish

Longest Processing Time (LPT) 6 15 18 6 8 Eng oun rke Ma lish 2 ting 8 ting Time until due: 23 3 Acc Processing time: 9

Longest Processing Time (LPT) 2 6 15 18 6 8 oun rke Ma ting

Longest Processing Time (LPT) 2 6 15 18 6 8 oun rke Ma ting 8 ting Time until due: 23 3 Acc Processing time: 9

Longest Processing Time (LPT) Superimposing due dates… 2 6 15 18 6 8 ting

Longest Processing Time (LPT) Superimposing due dates… 2 6 15 18 6 8 ting 8 oun Time until due: 23 3 Acc Processing time: 9

Longest Processing Time (LPT) Superimposing due dates… Processing time: 9 Time until due: 23

Longest Processing Time (LPT) Superimposing due dates… Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Longest Processing Time (LPT) Total days late = 48 = 9. 6 days Number

Longest Processing Time (LPT) Total days late = 48 = 9. 6 days Number of jobs 5 Avg. job lateness = Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Longest Processing Time (LPT) Makespan = 28 days + 17 + 23 +26 +28

Longest Processing Time (LPT) Makespan = 28 days + 17 + 23 +26 +28 = 103 Flow time = 9 Average flow time = 103 days/5 jobs = 20. 6 days/job Avg # jobs in system = 103 days/28 days = 3. 68 Utilization = 28 days/103 days = 27. 2% Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

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

Earliest Due Date (EDD) Process the job with the earliest due date first 18

Earliest Due Date (EDD) Process the job with the earliest due date first 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Earliest Due Date (EDD) 18 6 8 Eng oun anc rke Ma lish 15

Earliest Due Date (EDD) 18 6 8 Eng oun anc rke Ma lish 15 ting 6 e 2 ting 8 Acc Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Earliest Due Date (EDD) Ma 6 15 18 6 8 Eng anc lish 2

Earliest Due Date (EDD) Ma 6 15 18 6 8 Eng anc lish 2 e 8 ting rke Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Earliest Due Date (EDD) Ma 2 6 15 18 6 8 anc e 8

Earliest Due Date (EDD) Ma 2 6 15 18 6 8 anc e 8 ting rke Ma nag em ent Time until due: 23 3 Fin Processing time: 9

Earliest Due Date (EDD) Ma nag 2 6 15 18 6 8 e 8

Earliest Due Date (EDD) Ma nag 2 6 15 18 6 8 e 8 anc em ent Time until due: 23 3 Fin Processing time: 9

Earliest Due Date (EDD) Superimposing due dates… Processing time: 9 Ma nag em ent

Earliest Due Date (EDD) Superimposing due dates… Processing time: 9 Ma nag em ent Time until due: 23 3 8 2 6 15 18 6 8

Earliest Due Date (EDD) Superimposing due dates… Processing time: 9 Time until due: 23

Earliest Due Date (EDD) Superimposing due dates… Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Earliest Due Date (EDD) Superimposing due dates… Total days late = 6 Number of

Earliest Due Date (EDD) Superimposing due dates… Total days late = 6 Number of jobs 5 Avg. job lateness = Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8 = 1. 2 days

Earliest Due Date (EDD) Makespan = 28 days Superimposing due dates… Flow + 28

Earliest Due Date (EDD) Makespan = 28 days Superimposing due dates… Flow + 28 = 68 time = 2 + 8 + 11 + 19 Average flow time = 68 days/5 jobs = 13. 6 days/job Avg # jobs in system = 68 days/28 days = 2. 43 Utilization = 28 days/68 days = 41. 2% Processing time: 9 Time until due: 23 3 8 2 6 15 18 6 8

Summary Avg lateness Avg flowtime Avg #jobs utilization FCFS 2. 2 15. 4 2.

Summary Avg lateness Avg flowtime Avg #jobs utilization FCFS 2. 2 15. 4 2. 75 36. 4% LCFS 7. 6 18. 2 3. 25 30. 8% SPT 1. 8 13 2. 32 43. 1% LPT 9. 6 20. 6 3. 68 27. 2% EDD 1. 2 13. 6 2. 43 41. 2%

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last

Sequencing Rules (Single Resource) n Local ü ü ü First Come First Served Last Come First Served Shortest Processing Time Longest Processing Time Earliest Due Date Next class we’ll look at global rules and cover rules for multiple resources n Global ü Slack Per Remaining Operation ü Critical Ratio