Poka Yoke – Mistake Proofing

Posted on Author Antonio Ferraro

There are many different things in any facility which can cause waste. One of the biggest examples of this comes in the form of mistakes. Mistakes can happen during the production of a product, which then needs to be either fixed or disposed of. Whatever the cause, mistakes are a huge waste of time and resources. This is why the concept of poka-yoke was developed back in the 1960s. Poka-yoke is a term in Japanese which translates to “mistake proofing” in English.

It was developed by an industrial engineer at Toyota as a way to help reduce the number and severity of mistakes in the production line. Rather than simply reacting to a mistake, the poka-yoke system works to identify the root cause, and implement changes which will make it much more difficult, or even impossible, for the mistake to occur again.

How to Use Poka-Yoke

Understanding how to use poka-yoke is essential for any facility. Using this system is a great way to eliminate waste, and improve efficiency throughout the facility. The following steps can help anyone to mistake-proof their work area, or even an entire facility.

  • Identify the process for which it will be used. Taking the time to learn as much about the system as possible.
  • Analyze the ways which that process can fail.
  • Choose the proper poka-yoke approach. The following are the standard poka-yoke approaches to any issue:
    • Shut Out Type – Preventing the error from being made
    • Attention Type – Immediately highlight the fact that an error has been made
  • Determine whether any of the following options are appropriate for preventing this mistake in the future:
    • Contact – Using a physical attribute of an item as a way to detect errors. The size, weight, shape or other physical measurement can quickly identify mistakes in many types of production.
    • Constant Number – Identify mistakes by counting to ensure a consistent number of actions are taken in each process.
    • Sequence – Complete a checklist to ensure every action within the process has been completed.
  • Test the method and see if it is able to reduce or eliminate the number of mistakes occurring in a specific process.
  • Train everyone working on this system to use the new poka-yoke procedures


Constant Improvement

5S-guide-and-posterOne of the most significant benefits of the poka-yoke system is that it is ideal for fostering an environment of constant improvement. When mistakes are discovered, the poka-yoke system is used to either prevent the mistake from occurring again in the future, or put in checks to immediately discover the problem.  This helps to ensure the whole system runs smoothly, and when something does go wrong, the poka-yoke system is used again.

Rather than simply trying to address each mistake individually, poka-yoke actually works at identifying and addressing the root cause of all mistakes. Over time, this leads to a much more efficient and mistake-free production process. It will also allow the discovery and prevention of smaller and less significant mistakes, which in the past may have simply gone unnoticed. This is why poka-yoke is such an important system for all production situations, especially in lean environments.

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Antonio Ferraro

On behalf of Creative Safety Supply based in Portland, OR, I strive to provide helpful information to create safer and more efficient industrial work environments. My knowledge base focuses primarily on practices such as 5S, Six Sigma, Kaizen, and the Lean mindset. I believe in being proactive and that for positive change to happen, we must be willing to be transparent and actively seek out areas in need of improvement. An organized, safe, and well-planned work space leads to increased productivity, quality products and happier workplace. Connect with Antonio on Google+