1. Chapter 7 – Just-in-Time and Lean Systems
JIT philosophy
Meaning of waste in JIT
Differences bet. “push” and “pull” systems
Key elements of JIT manufacturing
Explain the elements of TQM and their role in JIT
Describe the role of people in JIT and why respect for people is so important
Understand impact of JIT on service and manufacturing
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2. Just-in-Time (JIT) Philosophy
Toyota developed JIT system in Japan, after WWII
Driven by a need survive after the devastation caused by the war
JIT gained worldwide prominence in the 1970s
JIT philosophy means getting the right quantity of goods at the right place and the right time
JIT is an all-encompassing philosophy found on eliminating waste or anything that does not add value (i.e., more than just inventory reduction)
A broad JIT view is one that encompasses the entire organization
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3. The Philosophy of JIT - continued
Often termed “Lean Systems”
Broad view that entire organization must focus on the same goal - serving customers
JIT is built on simplicity- the simpler the better
Focuses on improving every operation- Continuous improvement - Kaizen
Visibility – all problems must be visible to be identified and solved
Flexibility to produce different models/features
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4. Waste in Operations
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5. Waste in Operations (cont.)
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6. Waste in Operations (cont.)
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7. Three Elements of JIT
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8. Three Elements of JIT - continued
JIT manufacturing focuses on production system to achieve value-added manufacturing
TQM is an integrated effort designed to improve quality performance at every level
Respect for people rests on the philosophy that human resources are an essential part of JIT philosophy
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9. Elements of JIT Manufacturing
JIT Manufacturing is a philosophy of value-added manufacturing
Achieved by
Inventory reduction - exposes problems
Kanbans & pull production systems
Small lots & quick setups
Uniform plant loading
Flexible resources
Efficient facility layouts
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10. Role of Inventory Reduction
Inventory = Lead Time (less is better)
Inventory hides problems
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11. The Pull System
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12. Number of Kanbans Required
N = number of containers
D = demand rate at the withdraw station
T = lead time from supply station
C = container size
S = safety stock
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13. Computing the Number of Kanbans: an aspirin manufacturer has converted to JIT manufacturing using kanban containers. They wish to determine the number of containers at the bottle filling operation which fills at a rate of 200 per hour. Each container holds 25 bottles, it takes 30 minutes to receive more bottles, safety stock is 10% of demand during LT.
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14. Small Lot Sizes & Quick Setups
Small lots mean less average inventory and shorten manufacturing lead time
Small lots with shorter setup times increase flexibility to respond to demand changes
Strive for single digit setups- < 10 minutes
Setup reduction process is well-documented
External tasks- do as much preparation while present job is still running
Internal tasks- simplify, eliminate, shorten steps involved with location, clamping, & adjustments
Ultimate goal is single unit lot sizes
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15. Quick Setups SMED Principles Internal setup External setup
Separate internal setup from external setup
Convert internal setup to external setup
Streamline all aspects of setup
Perform setup activities in parallel or eliminate them entirely
Internal setup
Can be performed only when a process is stopped
External setup
Can be performed in advance
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16. Common Techniques for Reducing Setup Time
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17. Common Techniques for Reducing Setup Time (cont.)
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18. Common Techniques for Reducing Setup Time (cont.)
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19. Examples of Visual Control
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20. Examples of Visual Control (cont.)
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21. Uniform Plant Loading
A “level” schedule is developed so that the same mix of products is made every day in small quantities
Leveling the schedule can have big impact along whole supply chain
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22. Flexible Resources Moveable, general purpose equipment:
Portable equipment with plug in power/air
E.g.: drills, lathes, printer-fax-copiers, etc.
Capable of being setup to do many different things with minimal setup time
Multifunctional workers:
Workers assume considerable responsibility
Cross-trained to perform several different duties
Trained to also be problem solvers
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23. Effective Facility Layouts
Workstations in close physical proximity to reduce transport & movement
Streamlined flow of material
Often use:
Cellular Manufacturing (instead of process focus)
U-shaped lines: (allows material handler to quickly drop off materials & pick up finished work)
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24. Traditional Process Focused Layout
Jumbled flows, long cycles, difficult to schedule
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25. JIT Cellular Manufacturing
Product focused cells, flexible equipment, high visibility, easy to schedule, short cycles
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26. Cells with Worker Routes
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27. Worker Routes Lengthen as Volume Decreases
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28. JIT and TQM- Partners Build quality into all processes
Focus on continuous improvement - Kaizen
Quality at the source- sequential inspection
Jidoka (authority to stop line)
Poka-yoke (fail-safe all processes)
Preventive maintenance- scheduled
Work environment- everything in its place, a place for everything
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29. Respect for People: The Role of Employees
Genuine and meaningful respect for associates
Willingness to develop cross-functional skills
JIT uses bottom-round management – consensus management by committees or teams
Actively engage in problem-solving (quality circles)
Everyone is empowered
Everyone is responsible for quality: understand both internal and external customer needs
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30. Respect for People: The Role of Employees
Associates gather performance data
Team approaches used for problem-solving
Decisions made from bottom-up
Everyone is responsible for preventive maintenance
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31. The Role of Management Responsible for culture of mutual trust
Serve as coaches & facilitators
Support culture with appropriate incentive system including non-monetary
Responsible for developing workers
Provide multi-functional training
Facilitate teamwork
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32. Supplier Relationships and JIT
Use single-source suppliers when possible
Build long-term relationships
Work together to certify processes
Co-locate facilities to reduce transport if possible
Stabilize delivery schedules
Share cost & other information
Early involvement during new product designs
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33. Benefits of JIT Reduction in inventories Improved quality
Shorter lead times
Lower production costs
Increased productivity
Increased machine utilization
Greater flexibility
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34. Implementing JIT
Starts with a company shared vision of where it is and where it wants to go
Management needs to create the right atmosphere
Implementation needs a designated “Champion”
Implement the sequence of following steps
Make quality improvements
Reorganize workplace
Reduce setup times
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35. Implementing JIT - continued
Reduce lot sizes & lead times
Implement layout changes
Cellular manufacturing & close proximity
Switch to pull production
Develop relationship with suppliers
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36. JIT in Services
Most of the JIT concepts apply equally to Service companies
Improved quality such as timeliness, service consistency, and courtesy
Uniform facility loading to provide better service responsiveness
Use of multifunction workers
Reduction in cycle time
Minimizing setup times and parallel processing
Workplace organization
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