What is Poka Yoke?

When you hear the term “Poka Yoke” you may be thinking “Poka what?” While the practices known as Poka Yoke may be more prevalent in Japan, Poka Yoke is also gaining in popularity in the U.S. The term known as Poka Yoke was coined back in the 1960’s in Japan by a man known as Shigeo Shingo. Shingo was an industrial engineer working for the Toyota Company when he developed and formulated a plan to help reduce and eliminate mistakes and referred to as Poka Yoke or simply “mistake-proofing.” Inadvertent mistakes are one of the leading contributors towards waste in an industrial work environment and contribute to millions of dollars in lost time and revenue each year.

Consider this waste scenario

A company who specializes in the manufacturing of tape measures utilizes a multiple station approach when creating their products. Many would refer to this as simply assembly line production. As the unfinished products travel further down the assembly line, parts are added to each unfinished product until it reaches the end and is complete. However, after a shift change, an incoming employee unknowingly grabs a wrong bin of supplies containing an incorrect type of spinning mechanism and begins work as usual. Needless to say, a couple of hours later the mistake is realized and production is put to a standstill. Unfortunately, nearly 200+ products have been assembled incorrectly due to the incorporation of an incorrect spinning mechanism which hinders that tape measures’ ability to smoothly roll up. Not only did this mistake cause several hours of wasted production time, but this error also contributed towards wasted product parts which costs the company a loss in finances as well.

Poka Yoke to the Rescue!

The practice of Poka Yoke is helpful whenever there is a risk for mistakes. Essentially, Poka Yoke helps to make sure that processes work and function correctly the first time and make it virtually impossible to make a mistake.

When Shingo created the practice of Poke Yoke, he initially developed three different types (all referring to mass production levels).

  1. Contact Method – This type of method involves the detection of any deviation regarding a product’s physical characteristics or attributes such as color, size, or shape. An example of this may be something as simple as a mechanism that is able to detect upside down parts and then sends them out a chute. When I think about the contact method, I often think about the movie “Willy Wonka and the Chocolate Factory.” This same method is depicted in this movie when the golden eggs are placed on a scale and are rated either or good or bad based on weight and the bad eggs are thrown out.
  2. Fixed Value Method – This method often involves a set of chronological movements. For instance, if a specific number of movements is not conducted within a set amount of time an operator is alerted.
  3. Motion Step Method – This method is set to recognize a specific order of steps to be followed in order. This method strives for zero mistakes by making sure that an operator or specific process does not conduct steps that are not within the normal, accepted process constraints.

Poka Yoke can be a very powerful tool when implemented correctly and with genuine intentions. Familiarize yourself with this helpful “mistake-proofing” technique to help eliminate unwanted mistakes within your business.

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