Title: JIT and Lean Operations
1JIT andLean Operations
2JIT/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
3Goal of JIT
- The ultimate goal of JIT is a balanced system.
- Achieves a smooth, rapid flow of materials
through the system
4Summary JIT Goals and Building Blocks
Figure 14.1
5JIT Building Blocks
- Product design
- Process design
- Personnel/organizationalelements
- Manufacturing planning and control
6Product Design
- Standard parts
- Modular design
- Highly capable production systems
- Concurrentengineering
7Process Design
- Small lot sizes
- Setup time reduction
- Manufacturing cells
- Limited work in process
- Quality improvement
- Production flexibility
- Little inventory storage
8Benefits of Small Lot Sizes
9Personnel/Organizational Elements
- Workers as assets
- Cross-trained workers
- Continuous improvement
- Cost accounting
- Leadership/project management
10Manufacturing Planning and Control
- Level loading
- Pull systems
- Visual systems
- Close vendor relationships
- Reduced transaction processing
- Preventive maintenance
11Pull/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
12Traditional Supplier Network
Figure 14.4a
13Tiered Supplier Network
Figure 14.4b
First Tier Supplier
Second Tier Supplier
Third Tier Supplier
14Comparison 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
15Transitioning 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
16Obstacles to Conversion
- Management may not be committed
- Workers/management may not be cooperative
- Suppliers may resist
- Why?
17JIT 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
-
18Benefits of JIT Systems
- Reduced inventory levels
- High quality
- Flexibility
- Reduced lead times
- Increased productivity
19Benefits of JIT Systems (contd)
- Increased equipment utilization
- Reduced scrap and rework
- Reduced space requirements
- Pressure for good vendor relationships
- Reduced need for indirect labor
20CHAPTER
15
Scheduling
21Scheduling
- 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
22High-Volume Systems
- Flow system High-volume system with Standardized
equipment and activities - Flow-shop scheduling Scheduling for high-volume
flow system
23Scheduling Manufacturing Operations
- High-volume
- Intermediate-volume
- Low-volume
- Service operations
24High-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
25Intermediate-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
26Scheduling 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
27Gantt Load Chart
Figure 15.2
- Gantt chart - used as a visual aid for loading
and scheduling
28Loading
- Infinite loading
- Finite loading
- Vertical loading
- Horizontal loading
- Forward scheduling
- Backward scheduling
- Schedule chart
29Sequencing
- 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.
30Sequencing
- 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.
31Priority Rules
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
32Example 2
Table 15.4
33Two Work Center Sequencing
- Johnsons 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
34Johnsons 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
35Johnsons 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
36Scheduling 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
37Minimizing Scheduling Difficulties
- Set realistic due dates
- Focus on bottleneck operations
- Consider lot splitting of large jobs
38Scheduling 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
39Cyclical 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
40Service Operation Problems
- Cannot store or inventory services
- Customer service requests are random
- Scheduling service involves
- Customers
- Workforce
- Equipment
41Service Scheduling
SSU1 OverviewUnited Airlines
42Service Scheduling
SSU2 United Airlines Flight Schedule
43Schedule
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