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Scheduling – Day 2

Scheduling – Day 2

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Scheduling – Day 2

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  1. Scheduling – Day 2

  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. 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? English Finance Marketing Accounting Management

  13. Two resource problems Sequences tasks to minimize makespan Johnson’s Rule • 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? English Finance Marketing Accounting Management

  14. Two resource problems Sequences tasks to minimize makespan Johnson’s Rule • 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 English Finance Marketing Accounting Management

  15. Two resource problems Sequences tasks to minimize makespan Johnson’s Rule • 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 English Finance Marketing Accounting Management

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

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

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

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

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

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

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

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

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

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

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

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

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

  29. Sequencing Rules Single Resource Multiple Resources • Local • 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 availableDi = 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 3 3 4 3 4 5 3 Taylor Smith Simpson Allen Dickerson

  34. X = day working O = day off DAY OF WEEK M T W TH F SA SU MIN NO. OF WORKERS REQUIRED 3 3 4 3 4 5 3 Taylor Smith Simpson Allen Dickerson 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. D1 = D2 = D3 = D4 = D5 = D6 = D7 = N = 5 N – D1 = 5 – 3 = 2

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

  37. DAY OF WEEK M T W TH F SA SU MIN NO. OF WORKERS REQUIRED 3 3 4 3 4 5 3 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 If consecutive days off are desired, consider switching schedules among days with the same demand requirements. 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 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 If consecutive days off are desired, consider switching schedules among days with the same demand requirements.

  39. DAY OF WEEK M T W TH F SA SU MIN NO. OF WORKERS REQUIRED 3 3 4 3 4 5 3 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 If consecutive days off are desired, consider switching schedules among days with the same demand requirements. The revised schedule satisfies requirements with consecutive days off for most employees.