Just in Time - Kanban

JIT – KANBAN - TQM

Operations Management

Waste

Waste is ‘anything other than the minimumamount of equipment, materials, parts, space, and workers’ time which are absolutely essential to add value to the 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

Just-in-Time

� Downstream processes take parts from upstream as they need.

� Like an American Supermarket:� 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� 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 Source3. 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� 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� 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 immediatelyimmediately

� Not a lot of parts to sift through to find a good one

� Can’t 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� 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


Reducing WIP makesproblem very visible

STOP


Remove problem, runRemove problem, runWith less WIP


Reduce WIP again to findReduce WIP again to findnew 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 fasterto 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

� SmoothingMaster production schedule: 10,000 /mo.� 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 � 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

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� 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 1’s green tag giving it back to 1, and

� puts on her blue tag and moves it into position.


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� 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 2’s outbound pile,

� And gives the blue back to 2


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� 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 2’s outbound pile,

� And gives the blue back to 2

� 3’s production will be taken by 4, offstage right.

� Tag goes back into 3’s bin

6. Kanban

� Red finishes his part next.

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� Red finishes his part next.

� But 4 hasn’t 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 help

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How is this Different?

� Processes can become idled (blocked) or starved

� This makes you painfully aware of � 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 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

� Can’t afford to do huge runs

� Have to produce in small batches

� Toyota Die Change: 3 hours down to 3 SMED: under ten minutesSMED: under ten minutes

� Techniques� Make internal setups into External

� Eliminate Adjustments

� Eliminate the Setup

� Continuous Process Improvement, anyone?

Elimination of Waste

� Knew they wouldn’t beat U.S. with product innovation, concentrated on licensing patents, and producing more efficiently

� Costs prevented mass-production, volume � 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 � Toyoda made delivery trucks and motorcycles, and not many of either

Couldn’t Emulate GM

� GM huge batches in huge factories

� Japan’s area is 10% less than California and 70% agricultural.and 70% agricultural.

� 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

� GM’s large batches require large amounts of storage space.

� GM produces in large batches because of significant setup costs.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 didn’t 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 blew

2. Why the overload? Not lubricated2. 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 � Additional maintenance can prevent downtime, or minimize length of interruptions, when they do occur

Capacity Buffers

� System is inflexible, no inventory buffers, so to respond, need excess capacitycapacity

� 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� 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� Lack of trust between suppliers

� Firm encourages suppliers to share knowledge, because they don’t worry about competing

� Firm helps supplier increase quality, reduce costs

Lessons Learned from JIT

� The environment can be a control - don’t take setups for granted

� Operational details are very important (Ford, Carnegie)Carnegie)

� Controlling WIP is important

� Flexibility is an asset

� Quality can come first

� Continual improvement is necessary for survival

Just in Time - Kanban

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