Poka Yoke

Poka Yoke comes from Japan and was introduced by Shigeo Shingo as part of the Toyota production system. The word Poka stands for ‘unintentional error’ and Yoke means ‘to prevent’. Therefore, it is not about detecting or correcting an error, but preventing that error from ever being made. Poka Yoke is used to structure processes in a way that making mistakes is almost impossible.

THE 5 POKA YOKE STEPS

A Poka Yoke consists of the following five steps:

• Describe the defect;
• What is causing the defect? Go and look, go to the Gemba. Gemba means ‘the work floor’. This is where the process takes place and where the causes are hidden;
• Analyze the process that is causing the defect;
• What is the root cause of the defect? Look for the source;
• Consider and implement Poka Yoke. Make sure that this error can no longer be made in the future.

3 TYPES OF POKA YOKE

There are 3 types of Poka Yoke:

• Visual aids: these are tools you can see and it brings the process into view. This could include a road sign that indicates which way you can turn;
• Visual guides: these tools warn in the event of deviations and it controls the behavior. For example, a barrier that prevents you from going in a certain direction;
• Failsafe: ways to ‘force’ people to do something. For example, there is no other exit to arrive at a particular location.

TOOLS THAT ARE OFTEN USED IN POKA YOKE

In a Poka Yoke we use several Lean tools:

• Process Mapping: a visual overview of the process within the organization;
• 5 times Why: by asking the question ‘why’ 5 times, you will continue to get closer to the heart of the problem, and ultimately the solution;
• Go to the Gemba: Go to the work floor. This is where the processes take place and this is also the source of the errors;
• Cause and Effect Diagram: a tool that maps the problems. With this, you can improve production processes and quality control;
• FMEA (Six Sigma): stands for Failure Modes and Effects Analysis. It is a system that analyzes the design of a product or service system, and identifies possible errors. Then you can take steps to counter/minimize it.