Poka yoke

Poka Yoke (Mistake Proofing)Making it impossible for errors to be passed to the next step in a process

ABB Basic Quality Tools Series

© ABB Group 9AKK105151D0120

15 July 2010, Slide 1

Poka Yoke - ContentWhat is it for?

• To eliminate the possibility or opportunity for passing on errors or making mistakes in a process.

Where could I use it?

How do I use it?

• In the development or improvement of any process.

• When you want to make wrong actions impossible or more difficult to do.

• When there is a need to make it possible to reverse actions – to “undo” them – or make it harder to do what cannot be reversed

• When you need to make it easier to discover that errors occur.

Risks and how to avoid them

• Identify the errors/mistakes which could be passed on

• Develop potential solutions to prevent errors

• Develop potential solutions to detect errors

• Implement solutions

Example

© ABB Group 9AKK105151D0120

15 July 2010, Slide 2

Expected Benefits:

• Poka Yoke ensures that mistakes are not transferred to the next step of the process.

• Poka Yoke solutions are a simple and low cost way to reduce rework

Uses of this tool:

• Used to develop solutions to prevent mistakes before they occur or to detect errors and make it impossible for them to be passed on to the next step of the process.

• Can be used in the development of a new process or in an existing process where rework to correct errors is hurting process effectiveness and efficiency.

Poka Yoke - What is it for?

© ABB Group 9AKK105151D0120

15 July 2010, Slide 3

Background:

• Mistakes are human errors that result from incorrect intentions or executing correct intentions that result in unintended outcomes.

• The term poka-yoke comes from the Japanese words poka (accidental mistake) and yoke (prevent). Also known as ‘mistake-proofing’ or “error-proofing”.

• Shigeo Shingo developed poka-yoke while working at Toyota in the 1960’s

Uses:

• Use it to eliminates the cause of an error at the source or as it is being made.

• Use it to detect an error soon after it has been made, but before it reaches the next operation.

• In the development or improvement of any process.

• When you want to make wrong actions more difficult.

• When there is a need to make it possible to reverse actions – to “undo” them – or make it harder to do what cannot be reversed

• When you need to make it easier to discover that errors occur.

• When you want to reverse incorrect actions

Poka Yoke - Where could I use it?

© ABB Group 9AKK105151D0120

15 July 2010, Slide 4

Poka Yoke - How do I use it?

Define the potential mistakes /errors

Define the potential mistakes /errors

Procedure and Guidance Notes:• List potential mistakes / errors which could be transferred to the next

step in the process.Combine this with other tools (such as brainstorming).

Develop ways to prevent errors

Develop ways to prevent errors

• Investigate and analyse root causes Use other techniques such as Fishbone and 5 Whys for this step

Develop ways to detect errors

Develop ways to detect errors

• Brainstorm potential solutions for preventing the error

Make it obvious when something has been done incorrectly. E.g. make a system to identify product defects by testing the product's shape, size, color, or other physical attributes

Create & test solution

Create & test solution

• Brainstorm ideas to detect the error / deviation or mistake early

Consider characteristics of Poka Yoke solutions:Simple and low cost Part of the processIn place where the mistake can occurDoes not let the mistake exit the process

Identify Root Causes

Identify Root Causes

Implement solutionImplement solution

Find ways to make it impossible to do something incorrectly

• Develop solution to prevent or detect errors and test that it is effective.

• Implement solution and control output is effective (i.e. Errors are prevented and/or detected)

© ABB Group 9AKK105151D0120

15 July 2010, Slide 5

Poka Yoke - Risks and how to avoid them:Risks :• Not all potential errors are eliminated or detected

• Solutions are duplicated at different stages of the process.

• Potential solutions are complex and expensive

Steps to avoid them :• Make a thorough list of potential problems – use other

techniques, such as brainstorming to help and use the team. Use as many Poka Yoke devices as is necessary.

• Use flow charts to visualize the process so that mistake proofing solutions are not repeated

• Consider simple and cost effective solutions.

© ABB Group 9AKK105151D0120

15 July 2010, Slide 6

Poka Yoke - ExamplesElimination:

Detection:

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Poka Yoke - ExamplesSpellcheck:

Product Configurators:

Choices are automatically

limited depending on

context

Software:

© ABB Group 9AKK105151D0120

15 July 2010, Slide 8