1. JIT and Lean Operations

2. JIT/Lean Production
Just-in-time (JIT): A highly coordinated processing system in which goods move through the system, and services are performed, just as they are needed,
JIT   lean production
JIT  pull (demand) system
JIT operates with very little “fat”

3. Goal of JIT The ultimate goal of JIT is a balanced system.
Achieves a smooth, rapid flow of materials through the system

4. Summary JIT Goals and Building Blocks
Figure 14.1
Product
Design
Process
Personnel
Elements
Manufactur- ing Planning
Eliminate disruptions
Make the system flexible
Eliminate waste A
balanced
rapid flow
Ultimate
Goal
Supporting
Goals
Building
Blocks

5. JIT Building Blocks Product design Process design
Personnel/organizational elements
Manufacturing planning and control

6. Product Design Standard parts Modular design
Highly capable production systems
Concurrent engineering

7. Process Design Small lot sizes Setup time reduction
Manufacturing cells
Limited work in process
Quality improvement
Production flexibility
Little inventory storage

8. Benefits of Small Lot Sizes
Reduces inventory
Less storage space
Less rework
Problems are more apparent
Increases product flexibility
Easier to balance operations

9. Personnel/Organizational Elements
Workers as assets
Cross-trained workers
Continuous improvement
Cost accounting
Leadership/project management

10. Manufacturing Planning and Control
Level loading
Pull systems
Visual systems
Close vendor relationships
Reduced transaction processing
Preventive maintenance

11. Pull/Push Systems
Pull system: System for moving work where a workstation pulls output from the preceding station as needed. (e.g. Kanban)
Push system: System for moving work where output is pushed to the next station as it is completed

12. Traditional Supplier Network
Figure 14.4a
Buyer
Supplier

13. Tiered Supplier Network
Figure 14.4b
Supplier
Buyer
First Tier Supplier
Second Tier Supplier
Third Tier Supplier

14. Comparison of JIT and Traditional
Table 14.3
Factor
Traditional
JIT
Inventory
Much to offset forecast errors, late deliveries
Minimal necessary to operate
Deliveries
Few, large
Many, small
Lot sizes
Large
Small
Setup; runs
Few, long runs
Many, short runs
Vendors
Long-term relationships are unusual
Partners
Workers
Necessary to do the work
Assets

15. Transitioning to a JIT System
Get top management commitment
Decide which parts need most effort
Obtain support of workers
Start by trying to reduce setup times
Gradually convert operations
Convert suppliers to JIT
Prepare for obstacles

16. Obstacles to Conversion
Management may not be committed
Workers/management may not be cooperative
Suppliers may resist
Why?

17. JIT in Services
The basic goal of the demand flow technology in the service organization is to provide optimum response to the customer with the highest quality service and lowest possible cost.
Eliminate disruptions
Make system flexible
Reduce setup and lead times
Eliminate waste
Minimize WIP
Simplify the process

18. Benefits of JIT Systems
Reduced inventory levels
High quality
Flexibility
Reduced lead times
Increased productivity

19. Benefits of JIT Systems (cont’d)
Increased equipment utilization
Reduced scrap and rework
Reduced space requirements
Pressure for good vendor relationships
Reduced need for indirect labor

20. CHAPTER 15
Scheduling

21. Scheduling
Scheduling: Establishing the timing of the use of equipment, facilities and human activities in an organization
Effective scheduling can yield
Cost savings
Increases in productivity

22. High-Volume Systems
Flow system: High-volume system with Standardized equipment and activities
Flow-shop scheduling: Scheduling for high-volume flow system
Work Center #1
Work Center #2
Output

23. Scheduling Manufacturing Operations
High-volume
Intermediate- volume
Low-volume
Service operations
Build A
A Done
Build B
B Done
Build C
C Done
Build D
Ship
JAN
FEB
MAR
APR
MAY
JUN
On time!

24. High-Volume Success Factors
Process and product design
Preventive maintenance
Rapid repair when breakdown occurs
Optimal product mixes
Minimization of quality problems
Reliability and timing of supplies

25. Intermediate-Volume Systems
Outputs are between standardized high-volume systems and made-to-order job shops
Run size, timing, and sequence of jobs
Economic run size:

26. Scheduling Low-Volume Systems
Loading - assignment of jobs to process centers
Sequencing - determining the order in which jobs will be processed
Job-shop scheduling
Scheduling for low-volume systems with many variations in requirements

27. Gantt Load Chart
Figure 15.2
Gantt chart - used as a visual aid for loading and scheduling

28. Loading Infinite loading Finite loading Vertical loading
Horizontal loading
Forward scheduling
Backward scheduling
Schedule chart

29. Sequencing
Sequencing: Determine the order in which jobs at a work center will be processed.
Workstation: An area where one person works, usually with special equipment, on a specialized job.

30. Sequencing
Priority rules: Simple heuristics used to select the order in which jobs will be processed.
Job time: Time needed for setup and processing of a job.
Everything is #1 Priority

31. Priority Rules FCFS - first come, first served
Table 15.2
FCFS - first come, first served
SPT - shortest processing time
EDD - earliest due date
CR - critical ratio
S/O - slack per operation
Rush - emergency
Top Priority

32. Example 2 Average Number of Jobs at the Work Center
Table 15.4
3.24
9.67
22.17 CR
2.68
6.33
18.33
EDD
2.63
6.67
18.00
SPT
2.93
9.00
20.00
FCFS
Average Number of Jobs at the Work Center
Average Tardiness (days)
Average Flow Time (days)
Rule

33. Two Work Center Sequencing
Johnson’s Rule: technique for minimizing completion time for a group of jobs to be processed on two machines or at two work centers.
Minimizes total idle time
Several conditions must be satisfied

34. Johnson’s Rule Conditions
Job time must be known and constant
Job times must be independent of sequence
Jobs must follow same two-step sequence
Job priorities cannot be used
All units must be completed at the first work center before moving to second

35. Johnson’s Rule Optimum Sequence
List the jobs and their times at each work center
Select the job with the shortest time
Eliminate the job from further consideration
Repeat steps 2 and 3 until all jobs have been scheduled

36. Scheduling Difficulties
Variability in
Setup times
Processing times
Interruptions
Changes in the set of jobs
No method for identifying optimal schedule
Scheduling is not an exact science
Ongoing task for a manager

37. Minimizing Scheduling Difficulties
Set realistic due dates
Focus on bottleneck operations
Consider lot splitting of large jobs

38. Scheduling Service Operations
Appointment systems
Controls customer arrivals for service
Reservation systems
Estimates demand for service
Scheduling the workforce
Manages capacity for service
Scheduling multiple resources
Coordinates use of more than one resource

39. Cyclical Scheduling
Hospitals, police/fire departments, restaurants, supermarkets
Rotating schedules
Set a scheduling horizon
Identify the work pattern
Develop a basic employee schedule
Assign employees to the schedule

40. Service Operation Problems
Cannot store or inventory services
Customer service requests are random
Scheduling service involves
Customers
Workforce
Equipment

41. Overview—United Airlines
Service Scheduling
SSU1
Overview—United Airlines

42. United Airlines Flight Schedule
Service Scheduling
SSU2
United Airlines Flight Schedule

43. Painting Example (Washburn Guitar)
Schedule
PS8
Painting Example (Washburn Guitar)