Poka-Yoke is a Japanese term, which means minimizing the possibility of mistakes or errors. It is well known within Lean development and thinking. Originally it was called Baka-Yoke but, as that means “idiot-proof”, a more civil term was coined. What is Poka-Yoke in practice and what do we need it for?
Let’s start with a brief look into what Lean is. Lean is a method used to make production and service processes more effective. Through Lean, for example, all unnecessary, useless and even harmful can be removed from different processes. When successful, Lean is continuous instead of single projects. The organisation should incorporate the will to continuously enhance their processes. It is also important to communicate the processes and changes thoroughly, that is, to teach the employees to do the right thing — and not just to tell them, but to include them in the process development from start to the continuous endlessness and empower them to work independently in their everyday procedures without unnecessary eye-balling and ordering.
Now, let’s get to business. Poka-Yoke is part of all that Lean activity. By doing everyday procedures “idiot-proof”, unnecessary delays and even harmful accidents can be avoided. How? What are these magical Poka-Yokes that can be found everywhere in front of our eyes? Let me introduce you to an imaginary Jane and her regular day.
Examples of Everyday Poka-Yoke
Jane wakes up for the alarm on her phone and, while still mostly asleep, she manages to hit some buttons and the alarm is silenced. Nine minutes later the alarm goes off again because, through her random nibbling with the phone, the snooze function had kicked in: Poka-Yoke. Jane climbs down the stairs still half asleep and turns on the coffee maker. Tired and restless, Jane grabs the coffee pot mid-dripping and takes her first half cup. The coffee maker’s drip lock stops the coffee from dripping on the counter: Poka-Yoke. Jane crabs her vitamins from her pill dispenser which has a separate compartment for each day to ensure the correct amount every day: Poka-Yoke.
After finishing her coffee Jane heads out for her morning jog. She fetches her jogging pants from the drier. Again, the pants have almost sucked the waistband string inside — but luckily a small knot on the tip of the string saved it from vanishing inside the pants for eternity: Poka-Yoke. The previous night Jane had put her washer-dryer on for the night, but after getting in bed she heard beeping from the laundry room; She had forgotten to turn on the water and the washer refused to start the program: Poka-Yoke (with some Kanban and Jidoka elements: warning signal and automation which demanded human touch).
Because Jane is not in a hurry to leave for work after her morning jog, she decides to take a relaxing bath instead of the regular shower. She opens the bathtub faucet and, while the tub is filling, finishes emptying the drier. The tub fills up surprisingly quickly and when Jane turns off the water, it has been leaking to the overflow drain for quite some time instead of going to the floor causing a costly water damage: Poka-Yoke.
Then it is finally time for Jane to leave for work. Jane has dressed up and walks to her car. After a too long bath she’s now in a hurry and forgets to fasten her seatbelt. Luckily the car starts making an annoying beeping noise to remind her: Poka-Yoke (again with a hint of Kanban: warning sound). Then Jane notices a red light on the dashboard signalling a near-empty gas tank (also Kanban: signal light), so she takes a turn to the nearest gas station. Jane has recently changed her old diesel car to a newer regular petrol car and from an old habit drives to the diesel pump. Luckily for Jane, the diesel pistol is different shape from the petrol pistol and doesn’t fit her car saving Jane from delays and a call for the road service: Poka-Yoke.
Finally Jane reaches her office and takes her laptop from her bag. She connects the mouse and keyboard through an USB connection and her old screen with a VGA cable. She then connects to the organisation’s network with an ethernet cable. Each cable goes into their designated slots with ease and everything works: Poka-Yoke; The different shaped cable-ends ensure they are connected correctly.
Jane’s assistant brings her the mail, which includes the long-awaited new SIM card. Jane takes out the old card from her phone and installs the new one without problems. It goes in its slot easily because one of its corners is different from others and it cannot be installed in a wrong way: Poka-Yoke. The mail also had a bill in an envelope with a window, which ensures that whatever’s inside, it goes to the correct address: Poka-Yoke.
A Few Words of Poka-Yoke in General
Seems like Jane needs some time to get her day at work started so let’s leave her to it. Instead, let’s look at Poka-Yoke in a more general way.
Can Poka-Yoke eliminate msitakes altogether? No, of course not. We, people, make mistakes: It is in our nature and it is a part of our life, like it or not. Nevertheless Poka-Yoke helps avoiding big and fateful — and especially repeating — errors. The key in avoiding mistakes in work life is training of employees and gaining more experience.
This article is mainly based on Lean Management Training and Lean Specialist Certification online course by AIGPE, but my sources should not be blamed of possible mistakes in this text. If you notice a mistake or any inaccuracy, please let me know.