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Leveling: Tortoise not

Hare

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Ohno, 1988The slower but consistent tortoise causes less waste and is much more desirable than the speedy hare that races ahead and then stops occasionally to doze. The Toyota Production System can be realized only when all the workers become tortoises.

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The Leveling Paradox

The Leveling Paradox

Leveling provides a standardized core for Resource Planning Why do this to yourself ? Smoothing demand for upstream processes

How to Level Initial efforts to level production and mix Incremental leveling

Slice & Dice Product families and subfamilies

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Leveling: Core for Resource Planning

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ExampleCustomer Demand

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Heijunka1. Level, smooth production: product

volume

Customer Demand

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Heijunka 2. Level, smooth production: product mix

Customer Demand

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Monday Tuesday Wednesday Thursday Friday

Rake Shovel Spade

Customer Demand

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Rake Shovel Spade

Traditional production Level production

Rake Shovel Spade

Monday 100 50 25

Tuesday 100 50 25

Wednesday 100 50 25

Thursday 100 50 25

Friday 100 50 25

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Heijunka3. Level, smooth production: product

sequence

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Leveling High Variety Product Mix

High volume parts --> built-to-stock signal --> supermarket --> replenished by Kanban

Low volume parts --> built to customer order

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Why Leveling?

Problems: Small batches --> Frequent changeovers/change in material --> Lost production --> Missed schedule

Traditional solution: Large batches Less changeovers/change in material

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Why Leveling?

Toyota solution: Lifting the “cloud” Setup time reduction (SMED)

Increased flexibility Level material demand

Read Toyota Atsushi Niimi Interview

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Cell Design

Tool for one-piece flow

Cell: Group of workstations, machines or equipment arranged such that a product can be processed

progressively from one workstation to another w/o waiting for a batch to be completed and w/o additional handling between operations

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Traditional Layout

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Lean Cell Layout

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U-shaped Cell Example

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Designing Cells1. Group similar products into families that can be

processed on the same equipment in the same sequence

2. Calculate takt time

3. Determine the work elements and time required for making one piece

4. Determine equipment cycle time

5. Organize machines in order or processing (U-shaped)

6. Balance the cell

7. Determine how the work will be divided among operators

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Manage Change Process

Operators Crosstraining Job rotation Solve production problems Improvement suggestions Plan coordinate, and control their work Group setting

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Manage Change Process

Managers Planning Supervisors

Accounting

Reward system

Plan for demand changes

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Advantages Decreased

Transportation Waiting time WIP Floorspace Lead time

Increases flexibility (Variety and customization)

Better communication between operators --> improved quality and coordination

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Value Stream Mapping

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What is Value Stream Mapping

Value stream: Actions required to bring a product through the main flows essential to every product: Production flow from raw material to customer

delivery Design flow from concept to launch

Information flow as important as material flow

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Using the Mapping Tool

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Current-State Map

Material Flow Icons

General Icons

Information Flow Icons

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Material Flow Icons 1

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Material Flow Icons 2

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Information Flow Icons 1

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Information Flow Icons 2

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General Icons

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Characteristics of a Lean Value Stream

Produce to your takt time Takt time= rate of customer demand

Develop continuous flow wherever possible

Use supermarkets to control production where continuous flow does not extend upstream

Try to send the customer schedule to only one production process

Level the production mix

Level the production volume

Develop the ability to make “every part every day” (Level production sequence)

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The Future-State Map Goal:

Built a chain of production where the individual processes are linked to the customer and

Each process gets as close as possible to producing only what its customer needs when they need it

First pass: What can we do with what we have?

Later: Address product design, technology, and location issues

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Key Question for Future-State Map

Will you build to a finished goods supermarket from which the customer pulls, or directly to shipping?

What is the takt time?

At what single point in the production chain will you schedule production

Where will you need to use supermarket pull systems in order to control production of upstream processes

How will you level the production mix

What increment of work will you consistently release

What process improvements will be necessary

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Future-State Mapping Example

ACME Stamping Stamped-steel steering brackets

Hold the steering column to the body of a car Two versions: Left-hand side and right-hand-side

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Achieving the Future-State Map

Plan for achieving future-state map Future-state map Any detailed process-level maps or layouts that

are necessary A yearly value-stream plan

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Breaking Implementation into Steps

Divide into value-stream loops The pacemaker loop

Flow of material and information between your customer and your pacemaker process

Most downstream loop Impacts all the upstream processes in the value

stream Additional loops

Between pulls Each pull-system supermarkets separate loop

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The Value-Stream Plan

Shows: Exactly what to do when, step-by-step Measurable goals Clear checkpoints with real deadlines and

named reviewer(s)

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Determine Starting Point

Look for loops where: Process is well-understood by people Likelihood of success is high Big bang for the buck

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Improvement Pattern Develop a continuous flow that operates based

on takt time

Establish a pull system to control production

Introduce leveling

Practice kaizen to continually eliminate waste, reduce batch sizes, shrink inventory, and extend the range of continuous flow

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Conclusion

VSM cycle not one-time activity

Heart of day-to-day management

Serve the customer

Change in people

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Homework

Develop Future State Map for TWI

Due: 03/02/09 Before class