Quality Toolbox: Process Analysis Tools – Poka-Yoke

Poka-Yoke: Poka-yoke is the Japanese word for mistake-proofing, (for us ancients, the pre-politically correct term was idiot-proofing), and is not a new concept; some variation of this method has existed for as long as people have been producing products. Mistake-proofing, error-proofing, fool-proofing; whatever label that is attached to it, poka-yoke is any method that eliminates the possibility of doing something incorrectly.

Poka-yoke is, in essence, designing out the error; or more specifically, the human error.
Common poka-yoke solutions include checklists, dowel and locating pins, fixtures, error & alarm detectors, limit or touch switches, etc. An example of an offset tooling poka-yoke solution is presented in the attached figure, which makes it impossible for an operator to physically place the product incorrectly on a machine for processing. A properly designed poka-yoke will catch the errors before manufacturing defective product virtually 100% of the time.

The three rules of poka-yoke are: 1) Don’t wait for the perfect poka-yoke, do it now! 2) If your poka-yoke idea has better than a 50% chance to succeed, do it! and 3) Do it now, improve it later!