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STM Quality Limited

Poka-Yoke

TOTAL QUALITY MANAGEMENT

Poka-Yoke

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STM Quality Limited

This is known as ‘MISTAKE-PROOFING’

From Japanese:Yokeru (avoid)Poka (inadvertent errors)

What is Poka-Yoke?

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STM Quality Limited

What Does Poka-Yoke Do?

Eliminates the cause of an error at the source;

Detects an error as it is being made;

Detects an error soon after it has been made but before it reaches the next operation.

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STM Quality Limited

Are Errors Unavoidable?

There are two approaches to dealing with errors:

1. ERRORS ARE INEVITABLE!2. ERRORS CAN BE ELIMINATED!

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STM Quality Limited

1. Errors Are Inevitable

People always make mistakes.While we accept the mistakes as natural,

we blame the people who make them.With this attitude, we are likely to

overlook defects as they occur in production.

They may be detected at final inspection, or worse still, by the customer.

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STM Quality Limited

2. Errors Can Be Eliminated

Any kind of mistake people make can be reduced or even eliminated.

People make fewer mistakes if they are supported by proper training and by a production system based on the principle that errors can be avoided.

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STM Quality Limited

Inspection

One method of detecting errors is inspection.

There are two major types of inspection.

1. SAMPLING INSPECTION.2. 100% INSPECTION.

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STM Quality Limited

Sampling Inspection

In some factories, the attitude is: “It may take all day to inspect all

product”.“There may be a few defects, but

sampling is the most practical way to check”.

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STM Quality Limited

Sampling Inspection - Reflection

Think about sampling.

With sampling, there is a chance that an error may go undetected.

Even if 1 part in 1000 is defective, the customer who buys that part has a 100% defective product!

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STM Quality Limited

Sampling Inspection - Reflection

SAMPLING INSPECTION MAKES SENSE ONLY FROM THE

MANUFACTURER’S VIEW, NOT FROM THE CUSTOMER’S!

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STM Quality Limited

2. 100% Inspection

In the best factories, the attitude is:

“We won’t tolerate a single defect!”“We will organize production so

that 100% of the product can be easily inspected”.

“That makes the most sense”.

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STM Quality Limited

100% Inspection - Reflection

Think about 100% inspection.Even one defective product is

enough to destroy a customer’s confidence in a company.

To stay competitive a company must supply good product in thousands.

The best way to achieve this is to organize production to inspect 100% of the products.

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STM Quality Limited

The User Is The Best Inspector

No one intends to make mistakes.While we are working, errors can

show up without us noticing.How can we catch these errors

before they turn into defective products?

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STM Quality Limited

Finding Defects in the Subsequent Process

We don’t expect to find defects, but if a product we use doesn’t do what it is supposed to do, then we know it is defective.

Users are the best at discovering defects!

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STM Quality Limited

Finding Defects in the Subsequent Process

Since subsequent processes are also ‘users’ of the product being manufactured, they are also expert at finding defects.

If products are produced in a flow, each product is sent to the next process as soon as it is finished and defects are therefore found immediately.

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STM Quality Limited

Two Strategies for Zero Defects

1. DON’T MAKE IT!

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STM Quality Limited

1. Don’t Make It!

Don’t make product you don’t need.

The more you make, the greater the opportunity for defects.

Follow ‘just-in-time’ principles by only making what is needed, when it is needed in the amount needed.

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STM Quality Limited

Two Strategies for Zero Defects

2. Build Safeguards

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STM Quality Limited

2. Build Safeguards

The user is an expert in finding defects.

Therefore build safeguards into the production process.

Quality can be built into products by implementation of Poka-Yoke.

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STM Quality Limited

Poka-Yoke Devices

Human errors are usually inadvertent.

Poka-yoke devices help us avoid defects, even when inadvertent errors are made.

Poka-yoke helps build quality into processes.

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STM Quality Limited

Poka-Yoke Devices – Error Detection and Alarms

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STM Quality Limited

Poka-Yoke Devices – Checklists

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STM Quality Limited

Poka-Yoke Example

It is possible to mount the blank the wrong way onto the pierce tool.

BLANK PIERCED BLANK INCORRECT

As the blank can fit the pierce tool in many ways, how can this be prevented?

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STM Quality Limited

Poka-Yoke Example

By fitting a block into the pierce tooling, the blank plate can only go on one way.

BLOCK

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STM Quality Limited

Poka-Yoke

POKA-YOKE

MEANS

ZERO DEFECTS