1. Operations Management Short-Term Scheduling Chapter 15

2. Learning Objectives
When you complete this chapter, you should be able to :
Identify or Define:
Gantt charts
Assignment method
Sequencing rules
Johnson’s rules
Bottlenecks

3. Learning Objectives - continued
When you complete this chapter, you should be able to :
Describe or Explain:
Scheduling
Sequencing
Shop loading
Theory of constraints

4. Delta Airlines
10% of Delta’s flights disrupted per year - half of those by weather
Cost: $440-million in:
lost revenue
overtime pay
food and lodging vouchers
$33-million hi-tech nerve center
18 staff
$35-million savings (per year)

5. Strategic Implications of Short-Term Scheduling
By scheduling effectively, companies use assets more effectively and create greater capacity per dollar invested, which, in turn, lowers cost
This added capacity and related flexibility provides faster delivery and therefore better customer service
Good scheduling is a competitive advantage which contributes to dependable delivery

6. Short-Term Scheduling
Deals with timing of operations
Short run focus: Hourly, daily, weekly
Types
Today
Due Date B E
Forward Scheduling
Backward Scheduling

7. Short-Term Scheduling Examples
© T/Maker Co.
Hospital
Outpatient treatments
Operating rooms
University
Instructors
Classrooms
Factory
Production
Purchases

8. Scheduling Decisions Organization Managers Must Schedule
Operating room use
Patient admission
Nursing, security, maintenance staffs
Outpatient treatments
Classrooms and audiovisual equipment
Student and instructor schedules
Graduate and undergraduate courses
Production of goods
Purchase of materials
Workers
Mount Sinai Hospital
Indiana University
Lockheed-
Martin Factory

9. Scheduling Decisions Organization Managers Must Schedule
Chefs, waiters,bartenders
Delivery of fresh foods
Entertainers
Opening of dining areas
Maintenance of aircraft
Departure timetables
Flight crews, catering, gate, and ticketing personnel
Hard Rock Cafe
Delta Airlines

10. Capacity Planning, Aggregate Scheduling, Master Schedule, and Short-Term Scheduling
1. Facility size
2. Equipment procurement
Long-term
Aggregate Scheduling
1. Facility utilization
2. Personnel needs
3. Subcontracting
Intermediate-term
Master Schedule
1. MRP
2. Disaggregation of master plan
Intermediate-term
Short-term Scheduling
1. Work center loading
2. Job sequencing
Short-term

11. Forward and Backward Scheduling
Forward scheduling: begins the schedule as soon as the requirements are known
jobs performed to customer order
schedule can be accomplished even if due date is missed
often causes buildup of WIP
Backward scheduling: begins with the due date of the final operation; schedules jobs in reverse order
used in many manufacturing environments, catering, scheduling surgery

12. The Goals of Short-Term Scheduling
Minimize completion time
Maximize utilization (make effective use of personnel and equipment)
Minimize WIP inventory (keep inventory levels low)
Minimize customer wait time

13. Types of Planning Files
Item master file - contains information about each component the firm produces or purchases
Routing file - indicates each component’s flow through the shop
Work-center master file - contains information about the work center such as capacity and efficiency

14. Loading Jobs in Work Centers
Assigning jobs to work centers
Considerations
Job priority (e.g., due date)
Capacity
Work center hours available
Hours needed for job
Approaches
Gantt charts (load & scheduling) - capacity
Assignment method - job to specific work center

15. Options for Managing Facility Work Flow
Correcting performance
Increasing capacity
Increasing or reducing input to the work center by:
routing work to or from other work centers
increasing or decreasing subcontracting
producing less (or more)

16. Gantt Scheduling Chart
Start of an activity
Scheduled activity time allowed
Point in time when chart is reviewed S T W F
Day
Job
Job A
Job B
Job C
Maintenance
Now
End of an activity
Actual work progress
Non-production time
Day 1
Day 2
Day 3
Day 4
Day 5
Day 6
Day 7

17. Assignment Method Assigns tasks or jobs to resources
Type of linear programming model
Objective
Minimize total cost, time etc.
Constraints
1 job per resource (e.g., machine)
1 resource (e.g., machine) per job

18. Sequencing Challenge Order release Job Packet Job XYZ
Which job do I run next?
Dispatch List
Order Part Due Qty
XYZ
ABC
Production Control
Production

19. Sequencing Specifies order jobs will be worked Sequencing rules
First come, first served (FCFS)
Shortest processing time (SPT)
Earliest due date (EDD)
Longest processing time (LPT)
Critical ratio (CR)
Johnson’s rule

20. Priority Rules for Dispatching Jobs
First come, first served
The first job to arrive at a work center is processed first
Earliest due date
The job with the earliest due date is processed first
Shortest processing time
The job with the shortest processing time is processed first
Longest processing time
The job with the longest processing time is processed first
Critical ratio
The ratio of time remaining to required work time remaining is calculated, and jobs are scheduled in order of increasing ratio.
FCFS
EDD
SPT
LPT CR

21. First Come, First Served Rule
Process first job to arrive at a work center first
Average performance on most scheduling criteria
Appears ‘fair’ & reasonable to customers
Important for service organizations
Example: Restaurants

22. Shortest Processing Time Rule
Process job with shortest processing time first.
Usually best at minimizing job flow and minimizing the number of jobs in the system
Major disadvantage is that long jobs may be continuously pushed back in the queue.

23. Longest Processing Time Rule
Process job with longest processing time first.
Usually the least effective method of sequencing.

24. Earliest Due Date Rule Process job with earliest due date first
Widely used by many companies
If due dates important
If MRP used
Due dates updated by each MRP run
Performs poorly on many scheduling criteria

25. Critical Ratio (CR) Ratio of time remaining to work time remaining=
Work days
remaining
Due date -
Today'
s date =
Work (lead
) time remaining
Process job with smallest CR first
Performs well on average lateness

26. Advantages of the Critical Ratio Scheduling Rule
Use of the critical ratio can help to:
determine the status of a specific job
establish a relative priority among jobs on a common basis
relate both stock and make-to-order jobs on a common basis
adjust priorities and revise schedules automatically for changes in both demand and job progress
dynamically track job progress and location

27. Job Sequencing Example
Job Work
Processing time in days
Job Due Date (day) A 6 8 B 2 C 18 D 3 15 E 9 23

28. Summary Rule Average Completion Time (days) Utilization (%)
Average Number of Jobs in the System
Average Lateness (Days)
FCFS
15.4
36.4
2.75
2.2
SPT
13.0
43.1
2.32
1.8
EDD
13.6
41.2
2.43
1.2
LPT
20.6
27.2
3.68
9.6

29. Processing time in days
Critical Ratio (CR)
Job
Job Work
Processing time in days
Job Due Date (day)
Critical Ratio A 6 8
0.75 B 2
0.33 C 18
0.44 D 3 15
0.20 E 9 23
0.39
Sequence A C E B D

30. Johnson’s Rule
Used to sequence N jobs through 2 machines in the same order
© 1995 Corel Corp.
Saw
Drill
Job A
Job B
Job C
Jobs (N = 3)

31. Graphical Depiction of Job Flow
Work center 1
Work center 2
Time => B E D C A B E D C A
= Idle
= Job completed

32. Limitations of Rule-Based Dispatching Systems
Scheduling is dynamic; therefore, rules need to be revised to adjust to changes in process, equipment, product mix, etc.
Rules do not look upstream or downstream; idle resources and bottleneck resources in other departments may not be recognized
Rules do not look beyond due dates

33. Finite Scheduling System

34. Theory of Constraints
Deals with factors limiting company’s ability to achieve goals
Types of constraints
Physical
Example: Machines, raw materials
Non-physical
Example: Morale, training
Limits throughput in operations

35. Theory of Constraints A Five Step Process
Identify the constraints
Develop a plan for overcoming the identified constraints
Focus resources on accomplishing the constraints identified in step 2
Reduce the effects of the constraints by off-loading work or by expanding capability
Once one set of constraints is overcome, return to the first step and identify new constraints

36. Bottleneck Work Centers
Bottleneck work centers have less capacity than prior or following work centers
They limit production output
© 1995 Corel Corp.

37. Techniques for Dealing With Bottlenecks
Increase the capacity of the constraint
Ensure well-trained and cross-trained employees are available to operate and maintain the work center causing the constraint
Develop alternate routings, processing procedures, or subcontractors
Move inspections and tests to a position just before the constraint
Schedule throughput to match the capacity of the bottleneck

38. The 10 Commandments for Correct Scheduling
Utilization of a non-bottleneck resource is determined not by its own capacity but by some other constraint in the system
Activating a resource is not synonymous with utilizing a resource
An hour lost at a bottleneck is an hour lost of the whole system
An hour saved at a non-bottleneck is a mirage
The transfer batch may not, and many times should not, be equal to the process batch

39. The 10 Commandments for Correct Scheduling
The amount processed should be verifiable and not fixed
Capacity and priority need to be considered simultaneously, not sequentially
Damage from unforeseen problems can be isolated and minimized
Plant capacity should not be balanced
The sum of the local optimums is not equal to the global optimum

40. Scheduling for Services
Appointment systems - doctor’s office
Reservations systems - restaurant, car rental
First come, first served - deli
Most critical first - hospital trauma room

41. Cyclical Scheduling
Plan a schedule equal in weeks to the number of people being scheduled
Determine how many of each of the least desirable off-shifts must be covered each week
Begin the schedule for one worker by scheduling the days off during the planning cycle (at a rate of 2 days per week on average)

42. Cyclical Scheduling - Continued
Assign off-shifts for the first worker
Repeat this pattern for each other worker, but offset by one week from the previous
Allow each worker to pick his/her “slot” or “line” in order of seniority
Mandate that any changes from the chosen schedule are strictly between the personnel wanting to switch

43. Operations Management Just-in-Time and Lean Production Systems Chapter 16

44. Learning Objectives
When you complete this supplement, you should be able to :
Identify, Describe or Explain:
Just-in-Time (JIT) philosophy
Lean Production

45. Introductory Quotation
Waste is ‘anything other than the minimum amount of equipment, materials, parts, space, and worker’s time, which are absolutely essential to add value to the product.’
— Shoichiro Toyoda President, Toyota
© 1995 Corel Corp.

46. Green Gear Cycling
Designs and manufacturers high performance travel bicycles (bike-in-a-suitcase!)
Strategy is mass customization with low inventory, work cells, and elimination of machine setups.
Major focus on JIT and supply-chain management.
Two lines with seven work cells
One day throughput time
Focus on quality

47. What is Just-in-Time?
Management philosophy of continuous and forced problem solving
Supplies and components are ‘pulled’ through system to arrive where they are needed when they are needed.

48. Lean Production
Lean Production supplies customers with exactly what the customer wants, when the customer wants, without waste, through continuous improvement.

49. Types of Waste Overproduction Waiting Transportation
Inefficient processing
Inventory
Unnecessary motion
Product defects

50. Variability Occurs Because
Employees, machines, and suppliers produce units that do not conform to standards, are late, or are not the proper quantity
Engineering drawings or specifications are inaccurate
Production personnel try to produce before drawings or specifications are complete
Customer demands are unknown

51. Results
Queue and delay reduction, speedier throughput, freed assets, and winning orders
Quality improvement, reduces waste and wins orders
Cost reduction increases margin or reduces selling price
Variability reductions in the workplace reduces waste and wins orders
Rework reduction, reduces waste and wins orders

52. Faster response to the customer at lower cost and higher quality
Yielding
Faster response to the customer at lower cost and higher quality
A competitive advantage!

53. Just-in-Time Success Factors
Suppliers
Preventive Maintenance
Layout
Inventory
Scheduling
Quality
Employee Empowerment
JIT

54. Goals of JIT partnerships
Elimination of unnecessary activities
Elimination of in-plant inventory
Elimination of in-transit inventory
Elimination of poor suppliers

55. Concerns of Suppliers Diversification Poor customer scheduling
Frequent engineering changes
Quality assurance
Small lot sizes
Physical proximity

56. Inventory Traditional: inventory exists in case problems arise
JIT objective: eliminate inventory
JIT requires
Small lot sizes
Low setup time
Containers for fixed number of parts
JIT inventory: Minimum inventory to keep system running

57. Kanban Japanese word for card
Pronounced ‘kahn-bahn’ (not ‘can-ban’)
Authorizes production from downstream operations
‘Pulls’ material through plant
May be a card, flag, verbal signal etc.
Used often with fixed-size containers
Add or remove containers to change production rate

58. Quality JIT exposes quality problems by reducing inventory
JIT limits number defects with small lots
JIT requires TQM
Statistical process control
Worker involvement
Inspect own work
Quality circles
Immediate feedback

59. JIT Quality Tactics Use statistical process control Empower employees
Build failsafe methods (poka-yoke, checklists, etc.)
Provide immediate feedback

60. Employee Empowerment
Get employees involved in product & process improvements
Employees know job best!
JIT requires
Empowerment
Cross-training
Training support
Few job classifications
© 1995 Corel Corp.

61. All the techniques used in manufacturing are used in services
JIT in Services
All the techniques used in manufacturing are used in services
Suppliers
Layouts
Inventory
Scheduling

62. Attributes of Lean Producers - They
use JIT to eliminate virtually all inventory
build systems to help employees product a perfect part every time
reduce space requirements
develop close relationships with suppliers
educate suppliers
eliminate all but value-added activities
develop the workforce
make jobs more challenging
reduce the number of job classes and build worker flexibility

63. Operations Management Maintenance and Reliability Chapter 17

64. Learning Objectives
When you complete this chapter, you should be able to :
Identify or Define:
Maintenance
Mean time between failures
Redundancy
Preventive maintenance
Breakdown maintenance
Infant mortality

65. Learning Objectives - continued
When you complete this chapter, you should be able to :
Describe or Explain:
How to measure system reliability
How to improve maintenance
How to evaluate maintenance performance

66. NASA Maintenance of space shuttles Columbia: Maintenance requires
86,000,000 miles on odometer
3 engines each the size of a VW
expected to make dozens more launches
Maintenance requires
600 computer generated maintenance jobs
3-month turnaround
More than 100 people

67. Maintenance Management
All activities involved in keeping a system’s equipment working
Objective: Maintain system capability & minimize total costs
© 1995 Corel Corp.

68. The Strategic Importance of Maintenance and Reliability
Failure has far reaching effects on a firm’s
operation
reputation
profitability
customers
product
employees
profits

69. Maintenance Performance
Maintenance Procedures
Employee Involvement
Maintenance Performance
© 1995 Corel Corp.

70. Good Maintenance & Reliability Strategy
Requires:
Employee involvement
Maintenance and reliability procedures
To yield:
Reduced inventory
Improved quality
Improved capacity
Reputation for quality
Continuous improvement

71. Maintenance Benefits Lower operating costs Continuous improvement
Faster, more dependable throughput
Higher productivity
Improved quality
Improved capacity
Reduced inventory
Maintenance

72. Maintenance Decisions
How much preventive & breakdown maintenance
Who performs maintenance
Centralized, decentralized, operator etc.
Contract or in-house
When to replace or repair
How much to replace
Individual or group replacement

73. Types of Maintenance Preventive Breakdown
Routine inspection & servicing
Prevents failures
Bases for doing
Time: Every day
Usage: Every 300 pieces
Inspection: Control chart deviations
Non-routine inspection & servicing
Remedial
Basis for doing
Equipment failure

74. A Computerized Maintenance System

75. Contract for Preventive Maintenance
Compute the expected number of breakdowns without the service contract
Compute the expected breakdown cost per month with no preventive maintenance contract
Compute the cost of preventive maintenance
Compare the two options

76. Operations Manager Must Determine How Maintenance Will be Performed
Operator
Maintenance Department
Manufacturer’s field service
Depot Service (return equipment)
Competence is higher as we more
to the right
Preventive maintenance costs less and is faster as we move to the left

77. A Key To Success
High utilization of facilities, tight scheduling, low inventory and consistent quality demand reliability - total preventive maintenance is the key to reliability.

78. Techniques for Establishing Maintenance Policies
Simulation - enables one to evaluate the impact of various maintenance policies
Expert systems - can be used by staff to help diagnose faults in machinery and equipment

79. Lets finish with Discussion Questions
Page 632
Questions 1-5 & 10

80. 1. The objective of maintenance and reliability is to maintain the capability of the system while controlling costs.
2. Candidates for preventive maintenance can be identified by looking at the distributions for MTBF (mean time between failure).
If the distributions have a small standard deviation, they are usually a candidate for preventive maintenance.
3. Infant mortality refers to the high rate of failures that exists for many products when they are relatively new.

81. 4. Simulation is an appropriate technique with which to investigate maintenance problems because failures tend to occur randomly, and the probability of occurrence is often described by a probability distribution that is difficult to employ in a closed-form mathematical solution.

82. 5. Training of operators to perform maintenance may improve morale and commitment of the individual to the job or organization. On the other hand, all operators are not capable of performing the necessary maintenance functions or they may perform them less efficiently than a specialist. In addition, it is not always cost effective to purchase the necessary special equipment for the operator’s use.

83. 10. Only when preventive maintenance occurs prior to all outliers of the failure distribution will preventive maintenance preclude all failures. Even though most breakdowns of a component may occur after time, some of them may occur earlier. The earlier breakdowns may not be eliminated by the preventive maintenance policy. A distribution of natural causes exists.

84. Best wishes on your final
Best wishes on your final! More than that – I wish you success in your careers!
Chapters
1&2
11-17
Be sure to bring!
Blue Book
Scan-tron
Short form