JIT and Lean Operations - PowerPoint PPT Presentation

About This Presentation
Title:

JIT and Lean Operations

Description:

Lean Operations JIT/Lean Production Just-in-time (JIT): A highly coordinated processing system in which goods move through the system, and services are performed ... – PowerPoint PPT presentation

Number of Views:277
Avg rating:3.0/5.0
Slides: 44
Provided by: RalphB68
Category:

less

Transcript and Presenter's Notes

Title: JIT and Lean Operations


1
JIT andLean 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
5
JIT Building Blocks
  • Product design
  • Process design
  • Personnel/organizationalelements
  • Manufacturing planning and control

6
Product Design
  • Standard parts
  • Modular design
  • Highly capable production systems
  • Concurrentengineering

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
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
13
Tiered Supplier Network
Figure 14.4b
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 (contd)
  • 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

23
Scheduling Manufacturing Operations
  • High-volume
  • Intermediate-volume
  • Low-volume
  • Service operations

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.

31
Priority 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

32
Example 2
Table 15.4
33
Two 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

34
Johnsons 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
Johnsons Rule Optimum Sequence
  1. List the jobs and their times at each work center
  2. Select the job with the shortest time
  3. Eliminate the job from further consideration
  4. 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
Service Scheduling
SSU1 OverviewUnited Airlines
42
Service Scheduling
SSU2 United Airlines Flight Schedule
43
Schedule
PS8 Painting Example (Washburn Guitar)
Write a Comment
User Comments (0)
About PowerShow.com