What Poka-Yoke is
Poka-Yoke means "error-proofing" in Japanese. It's a simple mechanical or electronic device that physically prevents a defect from occurring, or alerts the operator the moment it would happen. It's the tool that makes the Jidoka principle practical.
The 3 types of device
Contact Method
Detects whether a part's shape, dimension, or position is correct through direct physical contact (guide pins, presence sensors).
Fixed-Value Method
Ensures an exact number of actions or parts was used before releasing the next step.
Motion-Step Method
Checks that each step of the standard sequence was carried out in the correct order before allowing the next.
The best quality control is the kind that makes the error physically impossible to happen.
Practical examples
- A USB connector that only fits one way
- A torque wrench that locks until it reaches the specified torque
- A digital checklist that blocks the next step until the previous one is confirmed
- A jig that only allows the correct part to be assembled in the correct place
Well-applied Poka-Yoke drastically reduces the need for 100% end-of-line inspection, one of the direct targets in the fight against the 8 wastes.
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.