1. 10/6 Production Sequencing Roll call/collect homework issues w/ Excel for CPM lecture: production sequencing small groups assign homework

2. CPM & Excel Deceptive: “on critical path”. Sensitivity report: shadow price of 1 or “LaGrange multiplier” of 1. Go to spreadsheet example.

3. Production Sequencing Multiple jobs, one work center (machine, person, etc.) Schedule to minimize mean flow time.

4. Production Sequencing: terms Work center: machine, person, etc., where some particular task is done. Scheduling: assigning jobs to work centers. Sequencing: the order in which to process the jobs at a given work center. Flow time: amount of time that passes from when an order was received and when it was finished.

5. Job Sequencing Priority Rules for Dispatching Jobs –FCFS- first come, first served –LCFS- last come, first served –SOT - shortest operation time –LOT- longest operation time –Ddate- due date

6. Job Sequencing: Example Copy shop w/ one color copier. Orders arrive in the morning in this order: –A. Brochures, 4 hrs.needed in 8 hrs. –B. Presentation, 1 hr.needed in 3 hrs. –C. Flyers, 6 hrs.needed in 7 hrs. –D. Invitations, 8 hrs.needed in 12 hrs. –E. Booklets, 5 hrs.needed in 14 hrs.

7. Job Sequencing: Example How to schedule to minimize the flow time? Orders arrive in the morning in this order: –A. Brochures, 4 hrs.needed in 8 hrs. –B. Presentation, 1 hr.needed in 3 hrs. –C. Flyers, 6 hrs.needed in 7 hrs. –D. Invitations, 8 hrs.needed in 12 hrs. –E. Booklets, 5 hrs.needed in 14 hrs.

8. Copy Shop: FCFS Arr.TimeDue A48 B13 C67 D812 E514 Arr.TimeDueFlow Time A480 + 4 = 4 B134 + 1 = 5 C675 + 6 = 11 D81211 + 8 = 19 E51419 + 5 = 24 tot. flow time = 4 + 5 + 11 + 19 + 24 = 63 mean flow time = 63 / 5 = 12.6 hrs.

9. Copy Shop: LCFS Arr.TimeDue A48 B13 C67 D812 E514 Arr.TimeDueFlow Time E5140 + 5 = 5 D8125 + 8 = 13 C6713 + 6 = 19 B1319 + 1 = 20 A4820 + 4 = 24 tot. flow time = 5 + 13 + 19 + 20 + 24 = 81 mean flow time = 81 / 5 = 16.2 hrs.

10. Copy Shop: SOT Arr.TimeDue A48 B13 C67 D812 E514 Arr.TimeDueFlow Time B130 + 1 = 1 A481 + 4 = 5 E5145 + 5 = 10 C6710 + 6 = 16 D81216 + 8 = 24 tot. flow time = 1 + 5 + 10 + 16 + 24 = 56 mean flow time = 56 / 5 = 10.2 hrs.

11. Copy Shop: LOT Arr.TimeDue A48 B13 C67 D812 E514 Arr.TimeDueFlow Time D8120 + 8 = 8 C678 + 6 = 14 E51414 + 5 = 19 A4819 + 4 = 23 B1323 + 1 = 24 tot. flow time = 8 + 14 + 19 + 23 + 24 = 88 mean flow time = 88 / 5 = 17.6 hrs.

12. Copy Shop: DDate Arr.TimeDue A48 B13 C67 D812 E514 Arr.TimeDueFlow Time B130 + 1 = 1 C671 + 6 = 7 A487 + 4 = 11 D81211 + 8 = 19 E51419 + 5 = 24 tot. flow time = 1+ 7 + 11 + 19 + 24 = 62 mean flow time = 62 / 5 = 12.4 hrs.

13. Job Sequencing: notes Note that the ending flow time was identical for all methods. (Additivity rule) The MEAN flow time varied. SOT will ALWAYS produce the lowest mean flow time.

14. Job Sequencing: 2 work centers Multiple jobs to do 2 work centers, jobs must be done sequentially (EX: first copy, then staple)

15. Johnson’s Rule: 2 work centers List the time for each job on each machine. Select the shortest operation time. If the shortest time is on 1st machine, schedule that job first. If the shortest time is on 2nd machine, schedule that job LAST. Repeat steps until all jobs are scheduled.

16. 2 work centers - Example Copy shop: 4 jobs to do, w/ times for each machine –bookletscopy: 3fold: 2 –brochurescopy: 6fold: 8 –catalogscopy: 5fold: 6 –packetscopy: 7fold: 4

17. 2 work centers - Example Step 1: find shortest time. 4 jobs to do, w/ times for each machine –bookletscopy: 3fold: 2 –brochurescopy: 6fold: 8 –catalogscopy: 5fold: 6 –packetscopy: 7fold: 4

18. 2 work centers - Example Step 2: on 2nd machine, so schedule it last. 4 jobs to do, w/ times for each machine –brochurescopy: 6fold: 8 –catalogscopy: 5fold: 6 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2

19. 2 work centers - Example Repeat: find lowest (remaining) time. 4 jobs to do, w/ times for each machine –brochurescopy: 6fold: 8 –catalogscopy: 5fold: 6 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2

20. 2 work centers - Example Repeat: 2nd mach., so move (next to) last. 4 jobs to do, w/ times for each machine –brochurescopy: 6fold: 8 –catalogscopy: 5fold: 6 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2

21. 2 work centers - Example Repeat: find lowest time. 4 jobs to do, w/ times for each machine –brochurescopy: 6fold: 8 –catalogscopy: 5 fold: 6 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2

22. 2 work centers - Example Repeat: 1st machine, move to front of line. 4 jobs to do, w/ times for each machine –catalogscopy: 5fold: 6 –brochurescopy: 6fold: 8 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2

23. 2 work centers - Example Done. 4 jobs to do, w/ times for each machine –catalogscopy: 5fold: 6 –brochurescopy: 6fold: 8 –packetscopy: 7fold: 4 –bookletscopy: 3fold: 2 catalogs brochures packets booklets Copy fold IDLE

24. Small Group Exercise You have an engraving business in a kiosk at the mall. Today, while you were out buying nachos, your clueless assistant received 4 orders in this sequence: a bracelet, which will take 10 min. to engrave, a locket (6 min.), an award plaque (24 min.), and a pen (12 min.). Your assistant also promised that they would be ready at 12:25, 12:15, 12:40, and 12:50, respectively. It is now 12:00 exactly. Minimize the number of dissatisfied customers by seeing which priority rule you should use. Should you fire your assistant?

25. Small Group Exercise timedue Bracelet1025 Locket615 Award2440 Pen1250 FCFSLCFSSOTLOTDdate B 10P 12L 6A 24L 6 L 16A 36B 16P 36B 16 A 40L 42P 28B 46A 40 P 52B 52A 52L 52P 52 # late 2 2 1 2 1 Choose DDate

26. 10/6 Homework DUE 10/8: Handout DUE 10/13: pg. 176, #20, pg. 177, #23