Poka-yoke

Japanese word for mistake proofing or error proofing, which translates to avoid (yokeru) mistakes (poka).

Shigeo Shingo, then an industrial engineer at Toyota Motor Corp., introduced the concept of poka-yoke (pronounced POH-kah YOH-kay) in 1961 within the Toyota Production System.

An example of his work occurred while helping workers assemble a small switch, who would often forget to insert the required spring under one of the switch buttons. In the redesigned process, the worker was forced to perform the task in two steps, first preparing the two required springs and placing them in a placeholder, then inserting the springs from the placeholder into the switch. When a spring was present in the placeholder, the workers knew that they had forgotten to insert it, and could correct the mistake quickly and effortlessly.

Shingo’s initial term was baka-yoke, which means “fool-proofing” or “idiot proofing.”

“Baka” often refers to a standard beyond people’s human ability, as opposed to “Poka” with a standard for people who have the ability, but are actively disengaged.

In 1963, a worker at Arakawa Body Co. refused to use baka-yoke mechanisms in her work area, because of the term’s dishonorable and offensive connotation. Subsequently, the term was changed to poka-yoke, which means “error-proofing” or “mistake-proofing.”

Links

• Wikipedia
• Re-Translating Lean from Its Origin