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Lean Production


Times New Roman Tahoma Wingdings Arial Blends Lean Production Waste Just-in-Time 7 Types of Waste (Ohno 1988) Seven Elements to Eliminate Waste 1. Focused ... – PowerPoint PPT presentation

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Title: Lean Production

Lean Production
  • Ron Tibben-Lembke

Operations Management
  • Waste is anything other than the minimum amount
    of equipment, materials, parts, space, and
    workers time which are absolutely essential to
    add value to the product.
  • --Shoichiro Toyoda President, Toyota Motor Co.
  • If you put your mind to it, you can squeeze water
    from a dry towel.
  • -- Eiji Toyoda, President 1967-1982

  • Downstream processes take parts from upstream as
    they need.
  • Like an American Supermarket
  • Get what you want
  • when you want it
  • in the quantity you want.

7 Types of Waste (Ohno 1988)
  • Overproduction
  • Time on Hand (waiting time)
  • Transportation
  • Stock on Hand - Inventory
  • Waste of Processing itself
  • Movement
  • Making Defective Products

Seven Elements to Eliminate Waste
  1. Focused Factories
  2. Group Technology
  3. Quality at the Source
  4. JIT production
  5. Uniform Plant Loading
  6. Kanban production control system
  7. Minimized setup times

1. Focused Factories
  • Small, specialized plants
  • No huge, vertically integrated plants
  • Small plants easier, cheaper to build
  • Tom Peters

2. Group Technology
  • Products grouped into families
  • Work cell can produce whole family
  • Cellular layout, not functional
  • Benefits
  • Much less inventory sitting around
  • Less material movement
  • Fewer workers
  • Cross-training
  • Keep skills sharp (managers too)
  • Reduce boredom fatigue
  • Understand overall picture, more new ideas

3. Quality at the Source
  • Do it right the first time
  • Stop process, correct errors immediately
  • Not a lot of parts to sift through to find a good
  • Cant afford high defect rates
  • Since low WIP, get quick feedback on errors

4. Just In Time-- What is It?
  • Just-in-Time produce the right parts, at the
    right time, in the right quantity
  • Requires repetitive, not big volume
  • Batch size of one
  • Short transit times, keep 0.1 days of supply

Lowering Inventory Reduces Waste
WIP hides problems
Lowering Inventory Reduces Waste
WIP hides problems
Lowering Inventory Reduces Waste
Reducing WIP makes problem very visible
Lowering Inventory Reduces Waste
Remove problem, run With less WIP
Lowering Inventory Reduces Waste
Reduce WIP again to find new problems
Performance and WIP Level
  • Less WIP means products go through system faster
  • reducing the WIP makes you more sensitive to
    problems, helps you find problems faster
  • Stream and Rocks analogy
  • Inventory (WIP) is like water in a stream
  • It hides the rocks
  • Rocks force you to keep a lot of water (WIP) in
    the stream

5. Uniform Plant Loading (heijunka)
  • Any changes to final assembly are magnified
    throughout production process
  • Smoothing
  • Master production schedule 10,000 /mo.
  • 500 day, 250 a shift
  • 480 minutes means 1 every 1.92 minutes
  • Sequencing
  • If mix is 50 A, 25 B, 25 C, produce
  • A-B-A-C-A-B-A-C

6. Kanban
  • Japanese for signboard
  • Method for implementing JIT
  • In order to produce, you need both material to
    work on, and an available kanban.
  • Each work station has a fixed kanbans.

6. Kanban
Flow of work
  • Worker 2 finishes a part, outbound moves over
  • 2 has a blue tag avaliable, so 2 gets another
    part to work on
  • 2 takes off 1s green tag giving it back to 1,
  • puts on her blue tag and moves it into position.

6. Kanban
Flow of work
  • When 3 finishes a part,
  • Finished parts move over one spot
  • He has to have a red tag available to put on,
  • He gets a part from 2s outbound pile,
  • And gives the blue back to 2

6. Kanban
Flow of work
  • When 3 finishes a part,
  • Finished parts move over one spot
  • He has to have a red tag available to put on,
  • He gets a part from 2s outbound pile,
  • And gives the blue back to 2
  • 3s production will be taken by 4, offstage
  • Tag goes back into 3s bin

6. Kanban
  • Red finishes his part next.
  • But 4 hasnt freed up any of the red kanbans, so
    there is nothing for 3 to work on now.
  • 3 could maintain his machine, or see if 4 needs

How is this Different?
  • Processes can become idled (blocked) or starved
  • This makes you painfully aware of problems in
    your system.
  • Material moves through the system so quickly no
    in-process recordkeeping is needed.

Importance of Flow
  • Ohno was very clear about this
  • Kanban is a tool for realizing just-in-time.
    For this tool to work fairly well, the process
    must be managed to flow as much as possible.
    This is really the basic condition. Other
    important conditions are leveling the product as
    much as possible, and always working in
    accordance with standard work methods.
  • -- Ohno, 1988, p. 3

7. Setup Reduction
  • Cant afford to do huge runs
  • Have to produce in small batches
  • Toyota Die Change 3 hours down to 3 SMED under
    ten minutes
  • Techniques
  • Make internal setups into External
  • Eliminate Adjustments
  • Eliminate the Setup
  • Continuous Process Improvement, anyone?

Elimination of Waste
  • Knew they wouldnt beat U.S. with product
    innovation, concentrated on licensing patents,
    and producing more efficiently
  • Costs prevented mass-production, volume strategy
    of American firms.
  • Find ways to reduce waste, cost
  • Shigeo Shingo (at right)
  • Taiichi Ohno, pioneers

-- the early years
  • First two Toyotas imported to U.S. 1957

JIT Origins in Japan
  • Post-WWII Japanese industry in ruins
  • Catch up to Americans in 4 years!
  • Toyoda made delivery trucks and motorcycles, and
    not many of either

Couldnt Emulate GM
  • GM huge batches in huge factories
  • Japans area is 10 less than California and 70
  • Put entire population of CA into 30 of state,
    then add 6 times as many people. (and you thought
    LA was crowded).
  • Land extremely expensive
  • Sprawling factories not an option

Small Batches
  • GMs large batches require large amounts of
    storage space.
  • GM produces in large batches because of
    significant setup costs.
  • If Toyota had the same large setup costs, it
    could never afford small batches.
  • Reduce setup cost to reduce batch size.
  • GM didnt think of doing this.

A contrasting opinion
  • Inventory is not the root of all evil, inventory
    is the flower of all evil.
  • - Robert Inman,
  • General Motors

Ask Why 5 Times
  • 5W 1H
  • 1. Why did the machine stop? Overload and fuse
  • 2. Why the overload? Not lubricated
  • 3. Why not lubricated? Oil pump not pumping?
  • 4. Why not pumping? Pump shaft worn out.
  • 5. Why worn out? No screen, scrap got in

Preventative Maintenance
  • Unexpected loss of production is fatal to system
    and must be prevented
  • Additional maintenance can prevent downtime, or
    minimize length of interruptions, when they do

Capacity Buffers
  • System is inflexible, no inventory buffers, so to
    respond, need excess capacity
  • Schedule less than 24 hours per day
  • Two-Shifting 4-8-4-8
  • Cross Training

Characteristics of JIT Partnershps
  • Few, nearby suppliers
  • Supplier just like in-house upstream process
  • Long-term contract agreements
  • Steady supply rate
  • Frequent deliveries in small lots
  • Buyer helps suppliers meet quality
  • Suppliers use process control charts
  • Buyer schedules inbound freight

Supplier Relationships
  • American model
  • keep your nose out of my plant.
  • Gain info to force price cuts
  • Lack of trust between suppliers
  • Firm encourages suppliers to share knowledge,
    because they dont worry about competing
  • Firm helps supplier increase quality, reduce costs

Lessons Learned from JIT
  • The environment can be a control - dont take
    setups for granted
  • Operational details are very important (Ford,
  • Controlling WIP is important
  • Flexibility is an asset
  • Quality can come first
  • Continual improvement is necessary for survival
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