1. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Chapter 13 Scheduling To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved.

2. Scheduling Specifies when labor, equipment, facilities are needed to produce a product or provide a service Specifies when labor, equipment, facilities are needed to produce a product or provide a service Last stage of planning before production occurs Last stage of planning before production occurs

3. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Scheduling by Process Type Process Industry Process Industry Linear programming Linear programming EOQ with noninstantaneous replenishment EOQ with noninstantaneous replenishment Mass Production Mass Production Assembly line balancing Assembly line balancing Project Project Project -scheduling techniques (PERT, CPM) Project -scheduling techniques (PERT, CPM)

4. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Scheduling Batch/Job Shop Operations Batch Production Batch Production Many planning steps Many planning steps Aggregate planning Aggregate planning Master scheduling Master scheduling Material requirements planning (MRP) Material requirements planning (MRP) Capacity requirements planning (CRP) Capacity requirements planning (CRP) Scheduling determines Scheduling determines Machine/worker/job assignments Machine/worker/job assignments Resource/requirement matching Resource/requirement matching

5. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Difficulties of Job Shop Scheduling Variety of jobs (customers) processed Variety of jobs (customers) processed Distinctive routing and processing requirements of each job/customer Distinctive routing and processing requirements of each job/customer Number of different orders in the facility at any one time Number of different orders in the facility at any one time Competition for common resources Competition for common resources

6. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. This Variety Necessitates Planning for the production of each job as it arrives Planning for the production of each job as it arrives Scheduling its use of limited resources Scheduling its use of limited resources Monitoring its progress through the system Monitoring its progress through the system

7. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. 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

8. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Shop Floor Control 1.Loading - Check availability of material, machines & labor 2.Sequencing - Release work orders to shop & issue dispatch lists for individual machines 3.Monitoring - Maintain progress reports on each job until it is complete

9. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Loading Allocate work to machines (resources) Allocate work to machines (resources) Perform work on most efficient resources Perform work on most efficient resources Use assignment method of linear programming to determine allocation Use assignment method of linear programming to determine allocation

10. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Assignment Method 1.Perform row reductions by subtracting minimum value in each row from all other row values 2.Perform column reductions by subtracting minimum value in each column from all other column values 3.Result is an opportunity cost matrix by crossing out all zeros in matrix using minimum number of horizontal & vertical lines

11. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Assignment Method 4.If number of lines equals number of rows in matrix, optimum solution has been found. Make assignments where zeros appear. Otherwise modify matrix by subtracting minimum uncrossed value from all uncrossed values & adding it to all cells where two lines intersect. All other values in matrix remain unchanged. 5.Repeat steps 3 & 4 until optimum solution reached

12. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Assignment Method COOKER FOOD1234 Beans105610 Peaches6246 Tomatoes7656 Corn95410 Row reductionColumn reductionCover all zeros 5015301434 501530143014 4024202323 402420232023 21010100 210101000100 5106310535 510631053105 Number lines  number of rows so modify matrix Example 13.1

13. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Assignment Method Example 13.1 Modify matrixCover all zeros 1012 10121012 0021 00210021 0320 03200320 1103 11031103 Number of lines = number of rows so at optimal solution FOOD1234 Beans1012 Peaches0021 Tomatoes0320 Corn1103 COOKER FOOD1234 Beans10610 Beans105610 Peaches246 Peaches6246 Tomatoes765 Tomatoes7656 Corn9510 Corn95410COOKER Orders completed in 6 hours

14. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Sequencing Prioritize jobs assigned to a resource Prioritize jobs assigned to a resource If no order specified use first-come first-served (FCFS) If no order specified use first-come first-served (FCFS) Many other sequencing rules exist Many other sequencing rules exist Each attempts to achieve to an objective Each attempts to achieve to an objective

15. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Sequencing Rules FCFS - first-come, first-served FCFS - first-come, first-served LCFS - last come, first served LCFS - last come, first served DDATE - earliest due date DDATE - earliest due date CUSTPR - highest customer priority CUSTPR - highest customer priority SETUP - similar required setups SETUP - similar required setups SLACK - smallest slack SLACK - smallest slack CR - critical ratio CR - critical ratio SPT - shortest processing time SPT - shortest processing time LPT - longest processing time LPT - longest processing time

16. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Critical Ratio Rule CR considers both time and work remaining CR = = If CR > 1, job ahead of schedule If CR < 1, job behind schedule If CR = 1, job on schedule time remainingdue date - today’s date work remainingremaining processing time

17. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Sequencing Jobs Through One Process Flowtime (completion time) Time for a job to flow through the system Flowtime (completion time) Time for a job to flow through the system Makespan Time for a group of jobs to be completed Makespan Time for a group of jobs to be completed Tardiness Difference between a late job’s due date and its completion time Tardiness Difference between a late job’s due date and its completion time

18. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68

19. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68 A055100 B51015150 C15217512 D178251213 E25631823 FCFSSTARTPROCESSINGCOMPLETIONDUE SEQUENCETIMETIMETIMEDATETARDINESS Example 13.2 FCFS

20. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68 C02250 E26880 A8513103 D13821129 B2110311516 DDATESTARTPROCESSINGCOMPLETIONDUE SEQUENCETIMETIMETIMEDATETARDINESS Example 13.2 DDATE

21. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules E06680 C62853 D8816124 A165211011 B2110311516 SLACKSTARTPROCESSINGCOMPLETIONDUE SEQUENCETIMETIMETIMEDATETARDINESS Example 13.2 PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68 SLACK Job A(10) - 5=5* B(15) - 10=5* C(5) - 2=3 D(12) - 8=4 E(8) - 6=2

22. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules E06680 D6814122 B141024159 A245291019 C29231526 CRSTARTPROCESSINGCOMPLETIONDUE SEQUENCETIMETIMETIMEDATETARDINESS Example 13.2 PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68 CR Job A(10) / 5=2.00 B(15) / 10=1.50 C(5) / 2=2.50 D(12) / 8=1.50 E(8) / 6=1.33

23. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules PROCESSINGDUE JOBTIMEDATE A510 B1015 C25 D812 E68 C02250 A257100 E761385 D13821129 B2110311516 SPTSTARTPROCESSINGCOMPLETIONDUE SEQUENCETIMETIMETIMEDATETARDINESS Example 13.2 SPT

24. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Simple Sequencing Rules FCFS18.609.623 FCFS18.609.6323 DDATE15.00 DDATE15.005.6316 SLACK16.406.8416 CR20.8011.2426 SPT6.0 SPT14.806.0316 AVERAGEAVERAGENO. OFMAXIMUM RULECOMPLETION TIMETARDINESSJOBS TARDYTARDINESS Example 13.2 Summary

25. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Sequencing Jobs Through Two Serial Process 1.List time required to process each job at each machine. Set up a one-dimensional matrix to represent desired sequence with # of slots equal to # of jobs. 2.Select smallest processing time at either machine. If that time is on machine 1, put the job as near to beginning of sequence as possible. 3.If smallest time occurs on machine 2, put the job as near to the end of the sequence as possible. 4.Remove job from list. 5.Repeat steps 2-4 until all slots in matrix are filled & all jobs are sequenced.

26. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 Example 13.3

27. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 Example 13.3

28. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 C Example 13.3

29. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 C Example 13.3

30. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 CE Example 13.3

31. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 CE Example 13.3

32. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCE Example 13.3

33. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCDE Example 13.3

34. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCDE Example 13.3

35. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCDE Example 13.3

36. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCDE Example 13.3 EADBC Process 1 (sanding)511203138 EADBC Process 2 (painting) 51523303741 Idle time Completion time

37. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Johnson’s Rule JOBPROCESS 1PROCESS 2 A68 B116 C73 D97 E510 ABCDE

38. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Sequencing Jobs Through Many Machines/Processes Facility is dynamic, new jobs added Facility is dynamic, new jobs added Develop global sequencing rules Develop global sequencing rules First-in-system, first-served (FISFS) First-in-system, first-served (FISFS) Work-in-next-queue (WINQ) Work-in-next-queue (WINQ) Fewest # remaining operations (NOPN) Fewest # remaining operations (NOPN) Slack per remaining operation (S/OPN) Slack per remaining operation (S/OPN) Remaining work (RWK) Remaining work (RWK) Study system via simulation Study system via simulation

39. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Guidelines for Selecting a Sequencing Rule 1.SPT most useful when shop is highly congested 2.Use SLACK or S/OPN for periods of normal activity 3.Use DDATE when only small tardiness values can be tolerated 4.Use LPT if subcontracting is anticipated 5.Use FCFS when operating at low-capacity levels 6.Do not use SPT to sequence jobs that have to be assembled with other jobs at a later date

40. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Monitoring Gantt Chart Gantt Chart Shows both planned and completed activities against a time scale Shows both planned and completed activities against a time scale Input / Output Control Input / Output Control Monitors the input and output from each work center Monitors the input and output from each work center

41. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Gantt Chart 12345689 10 1112Days 1 2 3 Today’s Date Job 32B Job 23C Job 11C Job 12A Facility Key: Planned activity Completed activity Behind schedule Ahead of schedule On schedule Figure 13.1

42. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Gantt Chart

43. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Input/Output Control Input/Output Report Planned input65657075 Actual input60606565 Deviation Planned output75757575 Actual output70706565 Deviation Backlog30 PERIOD1234TOTAL Example 13.4

44. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Input/Output Control Input/Output Report Planned input60657075270 Actual input60606565250 Deviation0-5-5-10-20 Planned output75757575300 Actual output70706565270 Deviation-5-5-10-10-30 Backlog3020101010 PERIOD1234TOTAL Example 13.4

45. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Advanced Planning and Scheduling Systems Infinite - assumes infinite capacity Infinite - assumes infinite capacity Loads without regard to capacity Loads without regard to capacity Then levels the load and sequences jobs Then levels the load and sequences jobs Finite - assumes finite (limited) capacity Finite - assumes finite (limited) capacity Sequences jobs as part of the loading decision Sequences jobs as part of the loading decision Resources are never loaded beyond capacity Resources are never loaded beyond capacity

46. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Advanced Planning and Scheduling Systems Advanced planning and scheduling (APS) Advanced planning and scheduling (APS) Add-ins to ERP systems Add-ins to ERP systems Constraint-based programming (CBP) identifies a solution space and evaluates alternatives Constraint-based programming (CBP) identifies a solution space and evaluates alternatives Genetic algorithms based on natural selection properties of genetics Genetic algorithms based on natural selection properties of genetics Manufacturing execution system (MES) monitors status, usage, availability, quality Manufacturing execution system (MES) monitors status, usage, availability, quality

47. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Theory of Constraints Not all resources are used evenly Not all resources are used evenly Concentrate on the” bottleneck” resource Concentrate on the” bottleneck” resource Synchronize flow through the bottleneck Synchronize flow through the bottleneck Use process and transfer batch sizes to move product through facility Use process and transfer batch sizes to move product through facility

48. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Synchronous Manufacturing Demand = 100 A’s Machine setup time = 60 minutes B A C D B1 5 B1 1 5 B2 3 B2 2 3 B3 7 B3 1 7 C1 2 C1 3 2 C2 10 C2 1 10 C3 15 C3 2 15 D1 10 D1 3 10 D2 8 D2 2 8 D3 5 D3 3 5 Operation j of item i performed at machine center k takes l minutes to process Item i Key: i Ij l Ij k l Example 13.5 MACHINE 1MACHINE 2MACHINE 3 B15B23C12 B37C315D35 C210D28D110 Sum2226*17

49. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Synchronous Manufacturing Demand = 100 A’s Machine setup time = 60 minutes B A C D B1 5 B1 1 5 B2 3 B2 2 3 B3 7 B3 1 7 C1 2 C1 3 2 C2 10 C2 1 10 C3 15 C3 2 15 D1 10 D1 3 10 D2 8 D2 2 8 D3 5 D3 3 5 Operation j of item i performed at machine center k takes l minutes to process Item i Key: i Ij l Ij k l Example 13.5 MACHINE 1MACHINE 2MACHINE 3 B15B23C12 B37C315D35 C210D28D110 Sum2226*17 Machine 1 Machine 3 Setup Completion time 10022322 122732 020012601940 2737 C2B1B3 C3B2D2 C1D1D3Idle Setup 1562 15121872 Setup Machine 2 Idle 2

50. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Solution Method 1. Identify bottleneck machine - sum process time of all operations to be performed on machine 2. Schedule first item whose lead time to the bottleneck is <= bottleneck processing time 3. Forward schedule the bottleneck machine 4. Backward schedule other machines to sustain bottleneck schedule 5. Recall that transfer batch size does not have to equal process batch size

51. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Employee Scheduling Labor is very flexible resource Labor is very flexible resource Scheduling workforce is complicated repetitive task Scheduling workforce is complicated repetitive task Assignment method can be used Assignment method can be used Heuristics are commonly used Heuristics are commonly used

52. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Employee Scheduling Heuristic 1.Let N = no. of workers available D i = demand for workers on day i X = day working O = day off 2.Assign the first N - D 1 workers day 1 off. Assign the next N - D 2 workers day 2 off. Continue in a similar manner until all days are have been scheduled. 3.If number of workdays for full time employee < 5, assign remaining workdays so consecutive days off are possible. 4.Assign any remaining work to part-time employees. 5.If consecutive days off are desired, consider switching schedules among days with the same demand requirements.

53. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Employee Scheduling DAY OF WEEKMTWTHFSASU MIN NO. OF WORKERS REQUIRED3343453 TaylorSmithSimpsonAllenDickerson Example 13.6

54. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Employee Scheduling DAY OF WEEKMTWTHFSASU MIN NO. OF WORKERS REQUIRED3343453 TaylorOXXOXXX SmithOXXOXXX SimpsonXOXXOXX AllenXOXXXXO DickersonXXOXXXO Completed schedule satisfies requirements but has no consecutive days off. Example 13.6

55. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. Employee Scheduling DAY OF WEEKMTWTHFSASU MIN NO. OF WORKERS REQUIRED3343453 TaylorOOXXXXX SmithOOXXXXX SimpsonXXOOXXX AllenXXXOXXO DickersonXXXXOXO The revised schedule satisfies requirements with consecutive days off for most employees. Example 13.6

56. To Accompany Russell and Taylor, Operations Management, 4th Edition,  2003 Prentice-Hall, Inc. All rights reserved. DSS for Scheduling Generate scheduling pattern to follow cyclically throughout the year; Generate scheduling pattern to follow cyclically throughout the year; Determine whether 40-hour or 80-hour base for overtime is more cost-effective; Determine whether 40-hour or 80-hour base for overtime is more cost-effective; Examine the effect of alternate-days-off patterns; Examine the effect of alternate-days-off patterns; Determine the appropriate breakdown of part-time verses full-time employees; Determine the appropriate breakdown of part-time verses full-time employees; Justify the use of additional staff; and Justify the use of additional staff; and Determine the benefit of cross-training employees in certain areas. Determine the benefit of cross-training employees in certain areas.