Poka-yoke (poh-kah yoh-keh) is a tool used in Lean and Six Sigma to identify steps in a process where an error is likely to occur, allowing managers to make changes to prevent them. It’s a useful tool that applies to any operation in any industry where errors can occur.
Poka-yoke is also known as error-proofing or mistake-proofing. Japanese engineer Shigeo Shingo coined the term in the late 1960s at Toyota, where it remains a key facet of the Toyota Production System (TPS).
Poka-yoke involves teams first mapping out every detail of a process. They then identify areas where mistakes can occur and work back through the steps to find the root cause. They then propose changes that make the process more likely to become mistake-proof.
Teams use poka-yoke both proactively and reactively. When setting up an operation or making changes, poka-yoke can identify points in the system where errors are most likely to occur. Teams can then eliminate those steps and replace them with less error-prone ones. Or, if they cannot replace the steps, teams create ways to minimize the risk of them happening. This often involves using the principles of the Jidoka system, a pillar of TPS that allows workers or automated machines to stop a process if they discover a defect – or even the potential for a defect.
If errors are found after an operation begins, poka-yoke can find the root cause and allow teams to redesign the process to avoid making the same mistakes again.
Examples of designing “mistake-proof” systems are frequent in everyday life. They include online forms that will not allow you to successfully hit the submit button without filling out all the fields. Another example is the creation of a chime or alarm sound that indicates people should get their card from an ATM or credit card machine, an invention that has cut down on people making the mistake of leaving behind their cards.
For businesses, using poka-yoke can protect profits and lower the risk of not producing a product on time or in a way that meets customer expectations.
