Poka Yoke


So, this is a wonky post, inspired by my time in some of the largest factories in the world. They all claim to be ‘Lean’…And all are, to a certain extent. Instead of writing volumes of NDA violating prose about those experiences, I want to write about some specific lean concepts that seem to be second-tier.

There are many mixed feeling about lean manufacturing, it’s risks, it’s benefits, and the usefulness of the whole concept. I understand the criticism, especially when companies focus on inventory/tooling reduction while ignoring process improvements, or  while ignoring their employee’s input and call it ‘lean’.

There are, however, two pillars of the Lean process that I feel are indisputably important, and often neglected. The first is a general respect for people. People are not only human, but the source of innovation, improvement, and thus profit. Treat humans humanely, and reap the benefit…Companies that don’t are, in essence, investing in a capital asset and only using half of its capabilities. Humans aren’t just a pair of hands. They have brains too. Why not use them? After all, you are paying for them.

The second is concept Poka-Yoke, or ‘mistake proofing’. I will write a little bit about Poka Yoke, because writing about respect for people would require my not ranting.

A simple Google search shows the (anecdotal) neglect of some lean concepts:

  • Search: “Lean” (“poka yoke” OR “Mistake Proofing” OR “mistake proof”) –414,000 results.
  • Search: “Lean” (“respect for people” OR “respect people” OR “respect workers”) –130,000 results
  • Search: “Lean” (“inventory reduction” OR “inventory management” OR “inventory cost”) –2,000,000 results
  • Search: “Lean” “inventory” –16,000,000 results.

Inventory reduction is, perhaps, the logical outcome of other Lean concepts/efforts…Not really the best starting place, even though that is where the effort is, since inventory is so easy to measure. People are the starting place, and their tools are things like Poka Yoke.

On Etymology (A Digression)

First, the term ‘Poka Yoke’ is Japanese in origin. It roughly translates to ‘error avoidance’. The term originally was ‘Baka-Yoke’, or ‘fool-proofing’, but if you look back a few paragraphs, respect for people is important. To paraphrase Shiego Shingo: Since everyone makes mistakes, the only true fool is the one that doesn’t learn from mistakes. Hence: Mistake-proof, not fool proof. Not Baka-Yoke, because we all err.

Back to the Point

Poka Yoke might mean using the key (or key fob) to lock your car, instead of the interior lock, thereby ensuring your keys are in your hand, and not in the ignition when locking your car.

It means minimizing risk through process.

In the film industry, we often used high-wattage lighting, and there were basic processes to protect ones-self…Touching a high voltage Bates connector with the back of your hand, so if you are shocked, your contracting muscles close your fist on empty air, not on the un- or badly-grounded connector.

On a related note: Bates connector was designed (decades ago), so it could only be attached in one orientation, preventing live and ground legs from being crossed.

It’s any process or mechanical implementation designed to prevent mistakes.

I saw it applied in the film industry, I see it applied in manufacturing, and one can generally see it everywhere. From plugs that can only go in one way to cars that won’t start unless they are in PARK…People called it all sorts of things, but it can be boiled down to a simple concept:

When possible, eliminate the possibility of mistakes.

 Poka Yoke at Home

The interesting thing is applying this concept to one’s home life. As mentioned with the key fobs, there are ways to improve even the simplest of daily routines.

Do you keep your coffee mug to the left of your laptop, even though you are right-handed? Prevent a spill, switch it up.

Do the garbage and recycling buckets in the kitchen look the same? Do they need to? Does this ever cause confusion?

Do shoes end up everywhere in the front hall? Huge factories lay tape down to define where pallets sit and people walk. Maybe a nice square of dark carpet would suggest a place for shoes to call home.

It’s the little stuff that makes a difference, but there is room for improvement everywhere.


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