1. Scheduling

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 Long Range Medium Range Short Range Manufacturing Services How much & when to produce How much & when to produce the end item How much & when to produce component items

3. Outline Scheduling What is it? Objectives Sequencing rules Single resource

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… All organizations perform scheduling to some extent…

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

6. In manufacturing organizations, managers schedule… Workers Purchases of materials Production of goods Foundry Milling machines LathesGrinding PaintingDrills Office Welding Forging Easier to schedule here Harder to schedule here … Sort WashDryIron

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

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

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

10. 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 - consider only current work center operation - consider current and all subsequent work center operations needed to complete job

11. 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

12. 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 Management Marketing Finance Accounting English 23 151868 9 3826 On the first day your given your English assignment Next, You are given an Accounting assignment… Processing time: Time until due:

13. 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 Management Marketing Finance Accounting English 23 151868 9 3826 What order do you work on the projects? Processing time: Time until due:

14. First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 What order do you work on the projects? Processing time: Time until due: Jobs are processed in order of arrival Which comes first?

15. First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

16. First Come First Served (FCFS) Management Marketing Finance Accounting 23 151868 9 3826 Processing time: Time until due:

17. First Come First Served (FCFS) Management Marketing Finance 23 151868 9 3826 Processing time: Time until due:

18. First Come First Served (FCFS) Management Marketing 23 151868 9 3826 Processing time: Time until due:

19. First Come First Served (FCFS) Management 23 151868 9 3826 Processing time: Time until due: Superimposing due dates… Management Marketing Finance Accounting English

20. First Come First Served (FCFS) 23 151868 9 3826 Superimposing due dates… Processing time: Time until due: So 3 projects are late!! How many weeks late? Management Marketing Finance Accounting English

21. First Come First Served (FCFS) 23 151868 9 3826 Superimposing due dates… Processing time: Time until due: So 3 projects are late!! How many weeks late? Management Marketing Finance Accounting English

22. First Come First Served (FCFS) 23 151868 9 3826 Processing time: Time until due: Avg. job lateness = Total days late Number of jobs = 11 5 = 2.2 days Management Marketing Finance Accounting English

23. total time to process all jobs = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Makespan: Flow time: Sum of times each job spends waiting, and being processed

24. = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time =68161928 ++++ = 77 Makespan

25. = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time == 77 Average flow time =Sum of flow times / # jobs Makespan

26. = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time = Average flow time =77 days/5 jobs = 15.4 days/job Makespan = 77

27. Sum of flow times / total processing time = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time == 77 Average flow time = = 15.4 days/job Avg # jobs in system = Makespan

28. Total processing time / sum of flow time = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time == 77 Average flow time = = 15.4 days/job Avg # jobs in system = 77 days/28 days = 2.75 Makespan Utilization =

29. = 28 days First Come First Served (FCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Flow time == 77 Average flow time = = 15.4 days/job Avg # jobs in system = 77 days/28 days = 2.75 Makespan Utilization = 28 days/77 days= 36.4%

30. 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

31. Last Come First Served (LCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: As jobs pile up the operator picks the one on the top of the stack to work on

32. Last Come First Served (LCFS) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

33. Last Come First Served (LCFS) Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

34. Last Come First Served (LCFS) Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

35. Last Come First Served (LCFS) Accounting English 23 151868 9 3826 Processing time: Time until due:

36. Last Come First Served (LCFS) English 23 151868 9 3826 Processing time: Time until due: Superimposin g due dates…

37. Last Come First Served (LCFS) 23 151868 9 3826 Processing time: Time until due: Superimposin g due dates… So 3 projects are late!!

38. Last Come First Served (LCFS) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates… Avg. job lateness = Total days late Number of jobs = 38 5 = 7.6 days

39. Last Come First Served (LCFS) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates… Flow time =9 12 202228 ++++ = 91 Average flow time =91 days/5 jobs = 18.2 days/job Avg # jobs in system = 91 days/28 days = 3.25 28 days Makespan = Utilization = 28 days/91 days= 30.8%

40. 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

41. Shortest Processing Time (SPT) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Process the job with the shortest processing time first

42. Shortest Processing Time (SPT) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

43. Shortest Processing Time (SPT) Management Marketing Finance English 23 151868 9 3826 Processing time: Time until due:

44. Shortest Processing Time (SPT) Management Finance English 23 151868 9 3826 Processing time: Time until due:

45. Shortest Processing Time (SPT) Management Finance 23 151868 9 3826 Processing time: Time until due:

46. Shortest Processing Time (SPT) Management 23 151868 9 3826 Processing time: Time until due: Superimposing due dates…

47. Shortest Processing Time (SPT) 23 151868 9 3826 Processing time: Time until due: Avg. job lateness = Total days late Number of jobs = 9 5 = 1.8 days Superimposing due dates…

48. Shortest Processing Time (SPT) 23 151868 9 3826 Processing time: Time until due: Flow time = 2 5 11 1928 ++++ = 65 Average flow time =65 days/5 jobs = 13 days/job Avg # jobs in system = 65 days/28 days = 2.32 28 days Makespan = Utilization = 28 days/65 days= 43.1%

49. 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

50. Longest Processing Time (LPT) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Process the job with the longest processing time first

51. Longest Processing Time (LPT) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

52. Longest Processing Time (LPT) Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

53. Longest Processing Time (LPT) Marketing Accounting English 23 151868 9 3826 Processing time: Time until due:

54. Longest Processing Time (LPT) Marketing Accounting 23 151868 9 3826 Processing time: Time until due:

55. Longest Processing Time (LPT) Accounting 23 151868 9 3826 Processing time: Time until due: Superimposing due dates…

56. Longest Processing Time (LPT) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates…

57. Longest Processing Time (LPT) 23 151868 9 3826 Processing time: Time until due: Avg. job lateness = Total days late Number of jobs = 48 5 = 9.6 days

58. 26 + Longest Processing Time (LPT) 23 151868 9 3826 Processing time: Time until due: Flow time = 9 17 23 28 + ++ = 103 Average flow time =103 days/5 jobs = 20.6 days/job Avg # jobs in system = 103 days/28 days = 3.68 28 days Makespan = Utilization =28 days/103 days= 27.2%

59. 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

60. Earliest Due Date (EDD) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due: Process the job with the earliest due date first

61. Earliest Due Date (EDD) Management Marketing Finance Accounting English 23 151868 9 3826 Processing time: Time until due:

62. Earliest Due Date (EDD) Management Marketing Finance English 23 151868 9 3826 Processing time: Time until due:

63. Earliest Due Date (EDD) Management Marketing Finance 23 151868 9 3826 Processing time: Time until due:

64. Earliest Due Date (EDD) Management Finance 23 151868 9 3826 Processing time: Time until due:

65. Earliest Due Date (EDD) Management 23 151868 9 3826 Processing time: Time until due: Superimposing due dates…

66. Earliest Due Date (EDD) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates…

67. Earliest Due Date (EDD) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates… Avg. job lateness = Total days late Number of jobs = 6 5 = 1.2 days

68. Earliest Due Date (EDD) 23 151868 9 3826 Processing time: Time until due: Superimposing due dates… Flow time = 2 8 111928 + + + + = 68 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% 28 days Makespan =

69. Summary Avg flowtime Avg lateness 2.2 Avg #jobs FCFS utilization LCFS SPT 7.6 1.8 15.4 18.2 13 2.75 3.25 2.32 36.4% 30.8% 43.1% LPT EDD 9.620.6 3.68 27.2% 1.213.6 2.43 41.2%

70. 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 Next class we’ll look at global rules and cover rules for multiple resources