Poka yoke

What is Poka Yoke? Fool-proofing, also called Poka Yoke, is one of the tools for Lean thinking for preventing errors as part of a value stream analysis. In the Lean Poka Yoke approach, we make a fundamental change to the design of the part or the process to prevent the error from occurring.

Consider a lean Poka Yoke example of contaminated blood as a result of using a hypodermic needle on more than one patient. A suitable poka yoke approach to prevent this error from occurring is to redesign the needle or syringe so that a needle may only be used a single time.

If parts can be put into fixtures incorrectly, so that a hole is drilled in the wrong location, then we could change the design of the part, or its fixture, or both, so that there is only one way for the part to fit into the fixture. A Poka Yoke example solution might add a pin to the fixture, with a mating slot added to the part, so that the part will not fit into the fixture unless the pin and slot are properly aligned.

If parts can be incorrectly assembled, then we can change their design so there is only one possible way to assemble them.

Automation is a very common way to minimize the occurrence of inadvertent errors by removing the human element. If part numbers can be incorrectly typed into the database, then a Poka Yoke example solution might use bar code readers to reduce the occurrence of incorrect entries.

Another Lean Poka Yoke approach that has proven helpful is an ergonomic approach of improving the work environment. An example Lean Poka Yoke solution might use a simpler keyboard or interface, easily accessible to the clerk, to reduce data entry errors.

Learn more about the Lean Six Sigma principles and tools for process excellence in Six Sigma Demystified (2011, McGraw-Hill) by Paul Keller, in his online Lean Six Sigma DMAIC short course ($249), or his online Green Belt certification course ($499).