Saturday, October 27, 2007

Poka Yoke

This is a very interesting concept... avoiding mistakes by design, or mistake-proofing called the Poka Yoke principle. The principle is widely used in the industry and in many real life situations. Well known examples including connectors you can't insert the wrong way because they are asymetrical, or the gas nozzle example. Type of gas (leaded/unleaded for instance in Europe) corresponds to a different diameter making impossible to insert the leaded gas nozzle in a car with a catalyzator.
A more detailed definition can be found in wikipedia : Poka Yoke Article

I recently discovered an interesting example of Poka Yoke or similar: when you buy medication in Europe, you'll get pills enclosed in plastic with an aluminium cover that can much too easily be opened.

Turkey 37

This is happening all the time, when you take a few pills with you for traveling for instance. The thing gets open, you lose the pill, a serious loss sometimes. If you buy similar pills in the US or in Canada, many times you will benefit from a different design.

Step one - the package
Turkey 32
Step two - peeling off the first layer
Turkey 33
Step three - getting the pill
Turkey 34

The aluminium foil is protected by a plastic/paper kind of surface, making it impossible to open or scratch the packaging by mistake. You need to peel off the first layer and then you can get the pill out of the package. This is a very intelligent mistake-proof design and probably a reasonably cheap one.

For other well known examples of poka yoke, there is a very interesting site:
Poka Yoke Examples


Luca said...

This isn't a poka all!!

Gugs said...

I don't agree with the previous comment. It might not be a classical example, but it is basically a design avoiding a user mistake. The first design is not fool proof while the second will avoid a faulty manipulation, a bit like the special caps on canisters to prevent children from opening them. It is a kind of mistake proofing.

Luca said...

Hi Gugs,
the second layer doesn't prevent completely to lose the pill, which is the problem mentioned for european conditioning. There's a chance to lose it.

Using a poka-yoke, you cannot have that chance. Just think to the gas nozzle, cans' poka yoke, usb or ethernet cable. It's like a YES or NO condition.

Unless I didn't really understand that pills' packaging.

The YES/NO condition is the basic in the industry to have mistake proofing. Nowadays you cannot have "expert" workers or spend a lot for specialised training in any sector.

Thing to create work instruction to use devices or item mentioned above (open a can and don't lose the chip, open the second ayer keeping the pill up, etc). If you need too many instruction it is not a PY (Usb or nozzle pump wouldn't need WI)

Nowadays anybody must be able to do anything with no safety issues and high productivity...sadly this it the truth.


Anonymous said...

Hi Luca,
I invite you to read about poka yoke , and you will find there are three types of them:
The first two, are meant to prevent and tell you if something is going wrong, but still they are not capable of completely solving the problem,
the third one is the one that even if you make something wrong, you won't have a deffect,
so yes, we do have a poka yoke example, even if its not of third kind of them.

Luca said...

Poka yoke is only lest in Japan. This attitude is so american, now you call everything poka yoke to say this is it, even if it is not! That's because it is far more difficult to have a REAL poka yoke. Isn't it?

Kaizen mindset became a joke thans to american "Lean Manufacturing", japanese PDCA has became similar to DMAIC talking to western people...and there's nothing else so different...not to talk about fake Kanbans or 'one-piece-flow'.

I don't say that your 3 kinds of 'poka yoke' are unuseful and you're free to call them what you want, but don't try to convince me.

I am sorry, but for me japanese Lean production or TPS is a phylosophy and not a series of 'tools' nor a justification to show up fake improvements on the shopfloor.

Anonymous said...

Quite agree Luca

Guy Van Hooveld said...

Again, I still think it is a kind of Poka Yoke. The first external layer is made of very hard plastic. You'll need a serious knife to even scratch it, making it virtually impossible to open without explicitely willing to. Under 'normal' circumstances, it is a perfect solution.