Poka-Yoke: types of making mistakes impossible

Poka-Yoke are simple devices that prevent a mistake or stop it passing unnoticed, instead of blaming the person. The best Poka-Yoke are cheap and come from the operator.

Two functions

• Prevention: the mistake cannot be made (a part that won't fit the wrong way).
• Detection: if it is made, it is noticed at once and the process stops or warns.

Three methods

• Contact: checking by a part's shape, size or colour.
• Fixed value: you can't proceed until a set number of motions or parts is complete.
• Motion step: the next step can't start until steps are done in the right order.

Recording it

Poka-Yoke can be set up as a record type: which mistake it prevents, its type, before–after photos and verification. A Poka-Yoke made in one area can be sent as a roll-out suggestion to other areas with similar lines.