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Poka-Yoke | you can’t go wrong

By Greg | May 12, 2009

Poka-Yoke examples and definition


Summary

Poka-Yoke: a simple idea that eliminates defects. Yes, makes it impossible to make an error. We are surrounded by Poka-Yoke kind of devices. This article explains what Poka-Yoke is and shows a few examples of Poka-Yoke devices as well as Poka-Yoke methods.

What is Poka-Yoke?

Even if you have never heard of Poka-Yoke you have certainly used more than one. Perhaps even on a daily basis. Poka-Yoke is as old as the ancient floppy disc (which can be inserted into the drive one way only), or perhaps even older.

Poka-Yoke is a device or method that prevents people from making mistakes. The word in Japanese means mistake proofing or error proofing. Originally the word Baka-Yoke or idiot proofing was used, but someone probably figured that even those of us who are not idiots make mistakes at times so now we use the word Poka-Yoke, and no reference to stupid people is made.

How to fight with defects?

The Toyota System or Lean Philosophy aims for perfection (it isn’t called Continuous Improvement by accident). In manufacturing producing sporadic defects is better than making frequent defects, but what if one defect can destroy the brand’s reputation or - even worse – put people in danger? In any case, each defect has the potential of pushing customers away from us and closer to our competitors. Traditional management’s first response would probably be something to the effect of setting up an effective quality check department. Let’s think about it.

Quality departments – do they eliminate defects?

A quality department usually operates in one of two ways. It can either check some products (for example – every 10,000th piece that leaves the production line) or every single product. The first option will definitely raise the standard of plant’s quality but it will not completely eliminate defects. The second option, checking every single piece produced or watching to make sure that every time a service is provided it is done the right way – is either very expensive or often impossible. Imagine fast food restaurant manager standing inside a restroom and making sure the staff wash their hands every single time they leave. I guess it’s possible, but who can guarantee that the manager won’t accidentally skip someone or favor some people?

Defects from Lean Perspective

Let’s look at the problem from the lean perspective. Producing a defect followed by detecting it and finally fixing it (or throwing it away) is Muda. Wouldn’t it be better just not to make the mistake in the first place? It’s not always possible, but wherever it is – let’s create a device (Poka-Yoke device) or develop some habits (Poka-Yoke method) that will simply make it impossible to make a mistake. For example – if we don’t want people to be exposed to harmful microwaves – why don’t we install a simple device in microwave ovens that automatically turns off the oven as soon as the door is opened? Or – if we don’t want to break an ATM machine – why don’t we cut one corner of a credit card to make sure there is only one way it can be inserted? If our kids keep losing that TV remote, why don’t we tape a piece of paper on the coffee table, trace the remote on it and then show the kids that this is one and only place where the remote can be placed after it’s used (this last method reduced the remote control loss rate from 3 times a day to probably once a week!)?

Poka-Yoke | Examples

1. Poka-Yoke devices


poka yoke examples

An example of a poka-yoke device


poka yoke examples

Another example of Poka-Yoke: no way to get it wrong


2. Poka-Yoke methods


poka yoke: example of a method

Poka-Yoke example: this simple habit will save your electric bill


poka yoke example

Poka-Yoke example: with this habit you will never forget to take your cellphone


In many companies where the Toyota System is used, Poka-Yoke devices are created every week or even every day. The Kaizen idea implies that they don’t have to be expensive and they are usually very simple. Every company, office, hospital, home, etc. where certain mistakes are not wanted, but where imperfect beings work or live, should give the idea of Poka-Yoke some thought. It might make a big difference.

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Topics: Lean Inventions | 17 Comments »

17 Responses to “Poka-Yoke | you can’t go wrong”

  1. abby, the hacker chick blog Says:
    September 6th, 2009 at 10:55 am

    Great description of Poka-Yoke & love the examples (especially the oven & the cellphone – rather makes us stop & think about what else we can poka-yoke in our lives!)

  2. Justin Hunter Says:
    September 8th, 2009 at 10:44 am

    Good post.

    I liked the rubber band example.

    I have a related post on my blog that highlights another aspect of the Toyota System and its relevance to software development and testing:

    http://hexawise.wordpress.com/2009/08/25/what-else-can-software-development-and-testing-learn-from-manufacturing-dont-forget-design-of-experiments/

    – Justin Hunter

  3. “Smart” applications « Riverside Publishing Next Generation Blog Says:
    September 25th, 2009 at 9:36 am

    […] The Japanese have a term – poka-yoke – which means “fail-safing” or “mistake-proofing.” The concept of poka-yoke first emerged as part of the Japanese “lean manufacturing” process made… In this process, a poka-yoke is any mechanism that helps an equipment operator (yokeru) avoid […]

  4. U.S.RATHEESH Says:
    March 6th, 2010 at 7:10 am

    Good Article…… Is there any way to apply Poka Yoke in purchase Process starting from sending enquiries to printing of Purchase Orders ?

  5. Nyak Ishak Says:
    March 7th, 2010 at 7:21 pm

    Very straigh forward explanation with nice illustrations of poka yoke.

    I would like to train personnel in Telco operations to practice poka yoke. any ideas? I am from Malaysia.

    Nyak Ishak

  6. REZA Says:
    October 6th, 2010 at 2:31 am

    VERY GOOD
    TANKS

  7. Cesar Says:
    October 7th, 2010 at 4:26 pm

    Very good article very understandable!.

  8. M.Srinivasan Says:
    July 28th, 2011 at 10:55 pm

    Sir,
    today only I gone thro your comments and I am interested in doing Poka-Yoke for any type of industries. Send me a mail for further queries.
    I am frequently visiting Malasia.
    Thanks.
    M.Srinivasan

  9. U.Sekar Says:
    September 13th, 2011 at 12:08 am

    Its great to learn about poke-yoke thro you is very useful in particular for small industries
    like us.
    Whats more with demo`s and video clips its wonderful to learn and makes every body to contribute their mite every day to improve their performace thro poka-yoke methode-
    I am going to implement the same in my factory as well at home.
    I am sure it will defenatly be a turning point in every body`s life if implemented every where.
    My very special thanks for your team who brought this in your website.
    Sekar U.
    +91 9283453459

  10. Rafael Vázquez - Torreón México Says:
    October 30th, 2011 at 9:38 am

    I really understood the main purpose of the Poka-Yoke system, the cellphone poka yoke was amazing, I am doing this exercise on daily basis, and I have added the car keys as well…

    Thank you !!

  11. V.Loganathan Says:
    April 10th, 2012 at 10:49 pm

    what is men by poka yoke expl

  12. Diana Lane Says:
    July 20th, 2012 at 6:50 pm

    I am always finding my husband’s and sons’ tools around the house and they get mad when I put them away in the wrong drawers. Solution: put a small strip of colored tape around the handle of each tool and a matching strip of tape on the drawer where each tool should go. Examples: blue for screwdrivers, red for metric wrenches, orange for SAE wrenches, green for electrical, etc.

  13. Govindaraj Says:
    November 9th, 2012 at 9:00 pm

    need more pictorial examples

  14. kalase R.S Says:
    November 20th, 2012 at 12:44 am

    please send the above presentation on above mail which wii be useful for our students of mechanical engineering.

    Prof.Kalase Rajesh S

  15. Nehal Says:
    March 17th, 2013 at 3:56 pm

    Thank you for this amazing information.You explained it well and make it easy to understand,,

  16. The new USB will be poka-yoke and user friendly | No Rules Just Words - Insights into change management Says:
    December 10th, 2013 at 1:09 am

    […] Poka-Yoke | you can’t go wrong […]

  17. DMAIC: Control | NHCP Quality Management Education Says:
    January 6th, 2014 at 4:04 pm

    […] pre-emptive or corrective action may be needed. The 5S technique can help sustain success. Poka-a-yoke (“mistake-proofing”) methods can prevent errors from […]

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