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Just-in-Time and Lean Systems

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Title: Just-in-Time and Lean Systems


1
Just-in-Time and Lean Systems
2
The Philosophy of JIT - Lean System (Production)
  • Central (1st) belief All waste (non value items)
    must be eliminated (started at Toyota Motor Co.)
  • excess inventory
  • backup equipment
  • anything (time, energy, space, human activity)
    that does not contribute to the value of the
    product/service
  • Other beliefs
  • 2. Broad view that entire organization must focus
    on serving customers
  • rather than focusing on their own jobs, employees
    know that they are ALL ultimately responsible for
    serving the customer (eliminate its not my job
    attitude)

3
The Philosophy of JIT - Lean System (Production)
  • 3. JIT is built on simplicity- the simpler the
    better
  • Encourages empl. to think about problems-gtsimple
    sol.
  • 4. Focuses on improving every operation- Kaizen
  • Continuous improvement An organization is never
    perfect and can always be improved in some way
  • 5. Install simple visible control systems
  • Make all waste visible open and clean floor
    space
  • 6. Flexibility to produce different
    models/features
  • Able to change volume
  • Able to produce variety of products

4
Three Elements of JIT
5
I. Elements of JIT Manufact.
  • 1.Inventory reduction exposes problems
  • 2. Kanbans pull production systems
  • 3. Small lots quick setups
  • 4. Uniform plant loading
  • 5. Flexible resources
  • 6. Efficient facility layouts

6
1. Role of Inventory Reduction
  • Inventory Lead Time (less is better)
  • Inventory hides problems

7
2. The Pull System
8
2. The Pull System
  • The amount produced at any one time is the amount
    in one container
  • Kanban cards coordinate the pull production
    system
  • Production cannot take place unless a container
    is empty and a production kanban has authorized
    production
  • A full container cannot be withdrawn unless a
    withdrawal kanban authorizes it

9
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 of DT (percent of demand
    during lead time)

10
Computing the No. of Kanbans an aspirin
manufacturer has converted to JIT manufacturing
using kanban containers. They wish to determine
the no. 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.Round down improvemen.
in the op. needed Round up excess inventory
11
3. 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- lt 10 minutes
  • The goal set up time 0 sec. and lot size 1
  • 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

12
4. 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

13
5. 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

14
6. 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)

15
Traditional Process Focused Layout
  • Jumbled flows, long cycles, difficult to schedule

16
JIT Cellular Manufacturing
  • Product focused cells, flexible equipment, high
    visibility, easy to schedule, short cycles

17
II. 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, i.e. prevent
    defects from occurring foolproof)
  • Preventive maintenance- scheduled
  • Work environment- everything in its place, a
    place for everything

18
III. Respect for People The Role of Employees
  • Genuine and meaningful respect for associates
  • Willingness to develop cross-functional skills
  • Actively engage in problem-solving (quality
    circles)
  • Everyone is empowered
  • Everyone is responsible for quality understand
    both internal and external customer needs
  • Associates gather performance data
  • Team approaches used for problem-solving
  • Decisions made from bottom-up
  • Everyone is responsible for preventive
    maintenance

19
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

20
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

21
Benefits of JIT
  • Smaller inventories
  • Shorter lead times
  • Improved quality
  • Reduced space requirements
  • Lower production costs
  • Increased productivity
  • Greater flexibility

22
Implementing JIT
  • Implementation needs a designated Champion
  • Make quality improvements
  • Reorganize workplace
  • Remove clutter minimize storage
  • Reduce setup times
  • Reduce lot sizes lead times
  • Implement layout changes
  • Cellular manufacturing close proximity
  • Switch to pull production
  • Extend methods to suppliers

23
JIT - Problems
  • Companies that use JIT have experienced a variety
    of problems.
  • Production systems need to be not only reliable,
    but also flexible to switching on the fly to
    meet an unexpected production change.
  • Typical problems involve
  • equipment downtime
  • the coordination and timing of subassembly
    production
  • setup losses
  • lack of supply reliability
  • use of forecasts in production (push, not pull
    system)

24
JIT - Problems (example)
  • One of the factories of Aisin, a brake-part
    supplier of Toyota that accounted for 80 of
    Toyotas purchased brake-parts, was destroyed by
    fire. This fire was a major problem since the
    supplier had only a three day supply of parts in
    its warehouse. At the time, both Toyota and
    Aisin were using all of their plants at full
    capacity. It was estimated that Toyota might
    miss selling 50,000 cars as a result of the fire.

25
JIT in Services
  • Most of the JIT concepts apply equally to Service
    companies
  • Cellular layouts, product focused, flexible
    employees shorten response times
  • Service inventory, paperwork, should be
    eliminated, simplified, examined for waste
  • Fail-safe all processes from Orders-Payment
  • Team based organizations

26
JIT in Services
  • McDonalds has implemented JIT in their program
    Made for You. This program, which was
    implemented a few years ago in the restaurants,
    consists of a making food to order. It consists
    of computerized kitchens with the use of some
    robotic technology. For example, machines dump
    fries into a basket, lower the basket into the
    oil and then remove the fries when done. The
    company revamped its point of service software,
    toasters, prep tables and holding bins. The
    prep tables were redesigned for a smooth, more
    efficient, work flows.
  • The easiest aspects of JIT to apply in services
    are the use of multifunction workers, cycle time
    reductions, setup time reductions, parallel
    processing, and workplace reorganization.

27
Chapter 07 problems
  • Problem 2
  • a.
  • D 10 thermostats per hour
  • T 30 minutes ½ hour
  • C 5 thermostats per container
  • N 1 Kanban (DT)/C 100.5/5
  • b.
  • S 2 thermostats
  • N 1.4 Kanbans (DT S)/C (5 2)/5

28
Chapter 07 problems
  • Problem 4
  • a.
  • D (50 units/hour)(1 hour/60 minutes) 0.8333
    units/minute
  • T 30 minutes
  • C 10 per container
  • N (0.8333)(30)/10 2.5 containers
  • b.
  • As the system improves, the cycle time decreases,
    hence the lead time T decreases, and therefore
    the number
  • N (DT S)/C of containers needed decreases (N
    may be rounded down to 2)

29
Chapter 07 problems
  • Problem 6
  • T 305 min. to transport 35 min.
  • C 20 units per container
  • N 5 containers
  • S 20 of the demand during lead time .2(DT)
  • N (DT S)/C --gt NC DT S --gt DT NC - S
  • DT NC - S NC - DT
  • DT DT NC
  • (1)DT NC --gt D NC/(1)T
  • D NC/1.2T 5(20)/(1.235) 2.38 units per
    minute 142.86 units per hour
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