Poka-Yoke: Is Mistake Proofing a Reality?

Is A Mistake Free Environment Possible?

Wouldn’t it be grand to have a process that runs ‘mistake proof’? For most, the idea of a mistake proof environment is business heaven. The real world tells us that mistakes and errors are all part of life and business. The idea is to have processes and procedures in place that reduce or eliminate mistakes. Mistake proofing, or its Japanese equivalent poka-yoke (pronounced PO-ka yo-KAY), is the use of any automatic device or process that either makes it impossible for an error to occur or makes the error immediately obvious once it has occurred. This is a method at the disposal of Lean Six Sigma practitioners to reduce and eliminate errors in process and procedures.

The Elements of Poka-Yoke

Like with any other tool in Lean Six Sigma, there are some steps you need to follow to get the most out of mistake proofing your projects. Here are the 7 steps that are crucial for implementation of mistake proofing:

1. Create a flowchart. Think about where errors will occur.
2. Identify the source or origin of each mistake.
3. Identify ways to prevent the errors from occurring.
4. Consider mitigation methods for errors that cannot be eliminated.
5. Identify the best method for mistake-proofing the process or device.
6. Inspect for errors by setting functions.
7. Set signals that alert workers for errors with regulatory functions.

Factors to Consider With Poka-Yoke

We sometimes depend on inspections conducted by workers to be fail safe for mistake proofing. While this does have some validity, humans are flawed and naturally prone to errors, even to the smallest degree. We can overcome these inspection defects through automation of the process. Automation will not accept a defect in the process, or create a defect in the process, or allow a defect to be passed to the next process. As with any other process, you must consider the cost of implementing poka-yoke mistake proofing methods. When determining the value of poka-yoke, you then must consider these expenses vs. the financial impact of defects reaching your customers.