1. Lecture 20 Production Activity Control (Revision)
Books
Introduction to Materials Management, Sixth Edition, J. R. Tony Arnold, P.E., CFPIM, CIRM, Fleming College, Emeritus, Stephen N. Chapman, Ph.D., CFPIM, North Carolina State University, Lloyd M. Clive, P.E., CFPIM, Fleming College
Operations Management for Competitive Advantage, 11th Edition, by Chase, Jacobs, and Aquilano, 2005, N.Y.: McGraw-Hill/Irwin.
Operations Management, 11/E, Jay Heizer, Texas Lutheran University, Barry Render, Graduate School of Business, Rollins College, Prentice Hall

2. Objectives Production activity control Gantt chart
Critical ratio scheduling
Finite loading
Scheduling
Assignment method
Sequencing
Slack
Johnson's Rule
Monitoring
Advance planning and scheduling
Scheduling procedure
Employee Scheduling

3. Production Activity Control
PAC in the MPC System
Shop Floor Control
Vendor Scheduling
Production Activity Control Techniques
Basic Data
Gantt Charts
Priority Scheduling
Finite Loading
Process Design Impact on Scheduling
Batch Manufacturing – Work Orders
Repetitive Manufacturing – JIT

4. Production Activity Control in the MPC System

5. Basic Data

6. Routing Data and Operation Setback Chart

7. Gantt Charts _____________________________________________________
The incoming orders at Tom's Sailboard follow different routes through the shop but all orders must stop at each of the three work centers in the plant. The table below shows all tasks for four jobs that arrive over 5 days and need to be scheduled at the company. It is currently November 10 and Tom works a seven-day week.
_____________________________________________________
Arrival Job/WC Processing time (days)
Order date routing WC 1 WC 2 WC 3
(B)iff Nov
(G)riffin Nov
(H)erbie Nov
(K)errie Nov
Assume that the new material for all orders is in stock and that a
first-come/first-served sequencing rule is used at all work centers. All three
work centers are idle as work begins on orders B and G on November 10.

8. Tom’s Sailboard
Construct a Gantt chart depicting the processing and idle times for the three work centers for these four jobs.
Arrival Job/WC Processing time (days)
Order date routing WC 1 WC 2 WC 3
(B)iff Nov
(G)riffin Nov
(H)erbie Nov
(K)errie Nov

9. Tom’s Sailboard
How many days does each job wait in queue for processing at work center 2?
The determination of how long jobs wait at work center 2 is as follows: B and G are processed immediately at work center 2, order K must wait 1 day (11/14) and order H waits 4 days (11/12, 11/13 at WC3) and (11/16 and 11/17 at WC2).

10. Priority Sequencing Rules
First Come, First Served
Shortest Operation Next
Earliest Due Date
Order Slack: (Time Remaining until Due Date – Sum of Remaining Setup and Run Time)
Slack per Operation
Critical Ratio: (Due Date-Now)/(Lead Time Remaining)
________________________________________
Lead Time Remaining includes setup, run, move and queue time for all remaining operations.

11. __________________________
Knox Machine
The jobs below are waiting to be processed at the P&W Grinder at the Knox Machine Company. (There are no other jobs and the machine is empty.)
__________________________
Machine processing Date job arrived Job due
Job time (in days)*__ at this machine date__ A B C D
*Note: This is the final operation for each of these jobs.
___________________________________________________________

12. Knox Machine: Solution
The production manager has heard about three dispatching rules: the Shortest Operation Next Rule, the First-Come/First-Served Rule, and the Earliest Due Date Rule. In what sequence would these jobs be processed at the P&W grinder if each rule was applied?
The shortest operation next rule: B-D-A-C
The first-come, first-served rule: D-A-B-C
The earliest due date rule: C-A-D-B
Machine processing Date job arrived Job due
Job time (in days)*__ at this machine date__ A B C D
*Note: This is the final operation for each of these jobs.

13. Knox Machine: Solution
If it's now the morning of July 10 and the Shortest Operation Next Rule is used, when would each of the four jobs start and be completed on the P&W grinder? (Express your schedule in terms of the calendar dates involved, assuming that there are 7 working days each week.)
P & W Grinder
Job B D A C
Date
7/10
7/11
7/12
7/13
7/14
7/15
7/16
7/17
7/18
7/19
7/20
7/21

14. Critical Ratio Scheduling
Eight weeks remain for constructing the a 50­foot yacht. Assume that each week consists of 5 work days, for a total lead time of 40 days. The work required to complete the yacht comprises 10 operations, 4 days for each.

15. Yacht Project Example
On Tuesday morning of week 3, 3 of the 10 operations had been completed and the yacht was waiting for the fourth operation. What's the critical ratio priority?

16. Yacht Project Example
What's the critical ratio priority if only 2 of the 10 operations are completed by Tuesday morning of week 3?

17. Finite Loading

18. The Bundy Company
The Bundy Company produces for three products (A, K, and P). Each order goes through the same three machine centers, but not necessarily in the same sequence. Each order must be finished at a machine center before another can be started. Orders cannot be split. The shop works a single eight-hour shift five days per week. Assume that the time to move between machines is negligible. each machine center is operated eight hours per day. All three machines are currently available for scheduling, and no further orders will arrive.

19. The Bundy Company Processing time Machine at machine center
center ___(in days)____ Order
Order routing due date A K P
Note: Order due dates are fixed based on the shop calendar. It is now 8:00 A.M. Monday (day 1), Monday of next week is day 6, etc.

20. The Bundy Company
Using the horizontal loading procedure with earliest-due-date priority sequencing rule, prepare a Gantt chart showing the production schedule for the three orders above.

21. The Bundy Company
Using the vertical loading procedure and the shortest-operation-next priority sequencing rule, prepare a Gantt chart showing the production schedule for the three orders above.

22. Scheduling

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

24. Scheduled Operations Batch Production Process Industry
Aggregate planning
Master scheduling
Material requirements planning (MRP)
Capacity requirements planning (CRP)
Process Industry
Linear programming
EOQ with non-instantaneous replenishment
Mass Production
Assembly line balancing
Project
Project -scheduling techniques (PERT, CPM)

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

26. Shop Floor Control (SFC)
Schedule and monitor day-to-day job shop production
Also called production control and production activity control (PAC)
Performed by production control department
Loading - check availability of material, machines, and labor
Sequencing - release work orders to shop and issue dispatch lists for individual machines
Monitoring - maintain progress reports on each job until it is complete

27. Loading Process of assigning work to limited resources
Perform work with most efficient resources
Use assignment method of linear programming to determine allocation

28. Assignment Method Perform row reductions Perform column reductions
subtract minimum value in each row from all other row values
Perform column reductions
subtract minimum value in each column from all other column values
Cross out all zeros in matrix
use minimum number of horizontal and vertical lines
If number of lines equals number of rows in matrix, then optimum solution has been found. Make assignments where zeros appear
Else modify matrix:
subtract minimum uncrossed value from all uncrossed values
add it to all cells where two lines intersect
other values in matrix remain unchanged
Repeat steps 3 and 4 until optimum solution is reached

29. Assignment Method Initial PROJECT Matrix 1 2 3 4 Bryan 10 5 6 10
Kari
Noah
Chris
Row reduction Column reduction Cover all zeros
Number lines  number of rows so modify matrix 12

30. Assignment Method Modify matrix Cover all zeros 1 0 1 2 1 0 1 2
Number of lines = number of rows so at optimal solution
Bryan
Kari
Noah
Chris
PROJECT
Bryan
Kari
Noah
Chris
Project Cost = ( ) X $100 = $2,100 12

31. Assignment Method - Setup
Solution goes here Only 1 leader can be assigned to each project
Click “Solve” for solution
Sum of all rows and columns = 1

32. Assignment Method - Solution
Assignments indicated by 1
Cost of solution

33. Sequencing Prioritize jobs assigned to a resource
If no order specified use first-come first-served (FCFS)
Other Sequencing Rules
FCFS - first-come, first-served
LCFS - last come, first served
DDATE - earliest due date
CUSTPR - highest customer priority
SETUP - similar required setups
SLACK - smallest slack
CR - smallest critical ratio
SPT - shortest processing time
LPT - longest processing time

34. Minimum Slack & Smallest Critical Ratio
SLACK considers both work and time remaining
CR recalculates sequence as processing continues and arranges information in ratio form
SLACK = (due date – today’s date) – (processing time)
time remaining due date - today’s date
work remaining remaining processing time
CR = =
If CR > 1, job ahead of schedule
If CR < 1, job behind schedule
If CR = 1, job on schedule

35. Sequencing Jobs Through One Process
Flow time (completion time)
Time for a job to flow through system
Makespan
Time for a group of jobs to be completed
Tardiness
Difference between a late job’s due date and its completion time

36. Simple Sequencing Rules
PROCESSING DUE
JOB TIME DATE
A 5 10
B 10 15
C 2 5
D 8 12
E 6 8

37. Simple Sequencing Rules: FCFSA B C D E
Total
Average /5 = /5 = 9.6
FCFS START PROCESSING COMPLETION DUE
SEQUENCE TIME TIME TIME DATE TARDINESS

38. Simple Sequencing Rules: DDATEB
Total
Average 75/5 = /5 = 5.6
DDATE START PROCESSING COMPLETION DUE
SEQUENCE TIME TIME TIME DATE TARDINESS

39. Simple Sequencing Rules: SLACK
B (15-0) – 10 = 5
C (5-0) – 2 = 3
D (12-0) – 8 = 4
E (8-0) – 6 = 2
SLACK START PROCESSING COMPLETION DUE
SEQUENCE TIME TIME TIME DATE TARDINESS E C D A B
Total
Average 82/5 = /5 = 6.8

40. Simple Sequencing Rules: SPT
SPT START PROCESSING COMPLETION DUE
SEQUENCE TIME TIME TIME DATE TARDINESS C A E D B
Total
Average 74/5 = /5 = 6

41. Simple Sequencing Rules: Summary
AVERAGE AVERAGE NO. OF MAXIMUM
RULE COMPLETION TIME TARDINESS JOBS TARDY TARDINESS
FCFS
DDATE
SLACK
SPT
Best values

42. Sequencing Jobs Through Two Serial Process
Johnson’s Rule
List time required to process each job at each process. Set up a one-dimensional matrix to represent desired sequence with # of slots equal to # of jobs.
Select smallest processing time at either process. If that time is on process 1, put the job as near to beginning of sequence as possible.
If smallest time occurs on process 2, put the job as near to the end of the sequence as possible.
Remove job from list.
Repeat steps 2-4 until all slots in matrix are filled and all jobs are sequenced.

43. Sequencing With Excel

44. Johnson’s Rule C E A B D JOB PROCESS 1 PROCESS 2 A 6 8 B 11 6 C 7 3

45. Johnson’s Rule A B C D E Completion time = 41 Idle time = 5+1+1+3=10 E
Process 1
(sanding) 5 11 20 31 38
Process 2
(painting) 15 23 30 37 41
Idle time
Completion time = 41
Idle time = =10

46. Excel for Johnson’s Rule
User inputs processing times and sequence
Excel calculates completion times and makespan
When the set of jobs is completed

47. Guidelines for Selecting a Sequencing Rule
SPT most useful when shop is highly congested
Use SLACK for periods of normal activity
Use DDATE when only small tardiness values can be tolerated
Use LPT if subcontracting is anticipated
Use FCFS when operating at low-capacity levels
Do not use SPT to sequence jobs that have to be assembled with other jobs at a later date

48. Monitoring Work package Shop paperwork that travels with a job
Gantt Chart
Shows both planned and completed activities against a time scale
Input/Output Control
Monitors the input and output from each work center

49. Gantt Chart 1 2 3 4 5 6 8 9 10 11 12 Days Today’s Date Job 32B Job 23C
Job 12A
Facility
Key:
Planned activity
Completed activity
Behind schedule
Ahead of schedule
On schedule

50. Input/Output Control PERIOD 1 2 3 4 TOTAL
Planned input
Actual input
Deviation
Planned output
Actual output
Backlog 30
PERIOD TOTAL

51. Input/Output Control PERIOD 1 2 3 4 TOTAL
Planned input
Actual input
Deviation
Planned output
Actual output
Deviation
Backlog
PERIOD TOTAL

52. Excel for Input/Output Control
User inputs planned and actual values
Excel calculates deviations and backlog

53. Advanced Planning and Scheduling Systems
Infinite scheduling - assumes infinite capacity
Loads without regard to capacity
Then levels the load and sequences jobs
Finite scheduling - assumes finite (limited) capacity
Sequences jobs as part of the loading decision
Resources are never loaded beyond capacity

54. Advanced Planning and Scheduling Systems
Advanced planning and scheduling (APS)
Add-ins to ERP systems
Constraint-based programming (CBP) identifies a solution space and evaluates alternatives
Genetic algorithms based on natural selection properties of genetics
Manufacturing execution system (MES) monitors status, usage, availability, quality

55. Advanced Planning and Scheduling

56. Theory of Constraints Not all resources are used evenly
Finite scheduling approach
Concentrate on the” bottleneck” resource
Synchronize flow through the bottleneck
Use process and transfer batch sizes to move product through facility

57. Drum-Buffer-Rope Drum Buffer Rope
Bottleneck, beating to set the pace of production for the rest of the system
Buffer
Inventory placed in front of the bottleneck to ensure it is always kept busy
Determines output or throughput of the system
Rope
Communication signal; tells processes upstream when they should begin production

58. Synchronous ManufacturingB A C D B B B C C C D D D
Item i
Key: i
Ij k l
Operation j of item i performed at
machine center k takes l minutes
to process

59. Synchronous Manufacturing
Demand = 100 A’s
Machine setup time = 60 minutes
MACHINE 1 MACHINE 2 MACHINE 3
B1 5 B2 3 C1 2
B3 7 C3 15 D3 5
C2 10 D2 8 D1 10
Sum * 17
* Bottleneck

60. Synchronous Manufacturing
Machine 1
Machine 3
Setup
Completion time
1002
2322 12
2732
200
1260
1940
2737 C2 B1 B3 C3 B2 D2 C1 D1 D3
Idle
1562
1512
1872
Machine 2 2

61. Employee Scheduling Labor is very flexible resource
Scheduling workforce is complicated, repetitive task
Assignment method can be used
Heuristics are commonly used

62. Employee Scheduling Heuristic
Let N = no. of workers available Di = demand for workers on day i X = day working O = day off
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
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

63. Employee Scheduling DAY OF WEEK M T W TH F SA SU MIN NO. OF
WORKERS REQUIRED
Taylor
Smith
Simpson
Allen
Dickerson

64. Employee Scheduling
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
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
Completed schedule satisfies requirements but has no consecutive days off

65. Employee Scheduling
DAY OF WEEK M T W TH F SA SU
MIN NO. OF
WORKERS REQUIRED
Taylor O O X X X X X
Smith O O X X X X X
Simpson X X O O X X X
Allen X X X O X X O
Dickerson X X X X O X O
Revised schedule satisfies requirements with consecutive days off for most employees

66. End of Lecture 20