Poka yoke is one of the many efficiency and quality assurance practices that arose from Toyota’s legendary production systems. It was popularized by manufacturing guru Shigeo Shingo, who first applied the practice with Toyota assembly line workers.
In fact, poka yoke’s funny name arose from a meeting Shingo had with employees at a Toyota plant. He explained the idea and then referenced it as an “idiot-proof” system. According to legend, the employees objected to the term, with one worker even bursting into tears before exclaiming, “I am not an idiot!”
Shingo quickly changed the terminology from “idiot-proof” to “mistake-proof.” Thus was born the term poka yoke, which means error-proofing or mistake-proofing in Japanese. It’s the idea of reducing the amount of decisions a human must make in a process, thereby eliminating opportunities for error.
If there’s room for improvement in your supply or distribution chain, poka yoke could be the solution.
Poka yoke may have been created in the automotive manufacturing industry, but it can be applied in nearly any process. Medical companies and health care providers use poka yoke ideas to reduce easily-avoidable errors. Electronics companies use the ideas to guide installation and implementation of software. Even furniture companies like IKEA use it to simplify product assembly.
The poka yoke philosophy is also applicable in the world of packaging and distribution. At Deufol, we implement poka yoke strategies on behalf of our customers to improve quality, reduce cost, and improve outcomes.
If there’s room for improvement in either your supply chain or distribution chain, poka yoke could be the solution. Below is information on how poka yoke works and how it could impact your efficiency and quality. If you haven’t implemented poka yoke strategies into your processes, now may be the time to do so.
What is Poka Yoke?
Poka yoke is simply the idea of eliminating opportunities for human error. Prior to poka yoke, manufacturers relied on inspections to minimize errors. While inspections can be valuable, they too often rely on human ability. The fact is that people of all talents and caliber make mistakes. It happens. Poka yoke uses tools and devices to minimize those mistakes.
The simplest example of poka yoke is the three-pronged plug. It could have been created with three identical prongs. However, that would have created inefficiency as the end user would have to use trial-and-error to determine which prong goes in which hole.
Instead, the plug was created with two flat or rectangular prongs that differ in size, along with a third round or semi-circle prong. The holes in the outlet align exactly with the prongs, so it’s immediately clear which prong goes in which hole. This eliminates errors and saves time. That’s poka yoke in its most basic form.
You probably use poka yoke strategies in your daily life on a regular basis. Spell-check alerts you to errors in your emails and documents, eliminating human error and minimizing editing time. Many email services now have features that check for the word “attachment.” If you use that word, but don’t attach a document, the email system alerts you to the possible error.
Again, these are simple versions of poka yoke. In the manufacturing world, poka yoke can be introduced at scale to protect quality and drive efficiency.
Poka yoke strategies often fall into three categories:
1. Contact Device
In poka yoke methodology, the contact mechanism is one that physically does not allow a mistake to happen. Again, the three-prong plug is a perfect example. The prongs will only fit in the holes that match their shape. A SIM card on your phone is another example. SIM cards have a unique shape so they can only fit into your phone the correct way. It’s impossible to insert them incorrectly.
In manufacturing world, a contact device may be a pin that prevents a part from being assembled incorrectly. It could be a oddly-shaped parts that force the correct assembly.
2. Fixed Value
A fixed-value approach is one that uses contact poka yoke, but also integrates visual guidance. Fixed-value tactics are often used to control quantities. Classic examples include an egg tray style containers that only have enough space for the exact number of parts. Certain prescriptions, like birth control, are often distributed in packaging that highlights exactly which pill on which days.
Packaging for an injection pen device (such as an insulin pen) which aims to educate users in a step-by-step way. Error-proof medical decive packaging — Burgopak
Manufacturers can use similar tactics to ensure the right amount of parts are used at each step. Parts can be bundled so it’s impossible for an employee to use too many or too few. For example, if a step requires exactly three screws, the manufacturer could distribute screws in bags of three.
3. Motion Stop
Motion stop poka yoke strategies prevent mistakes by stopping forward progress in an operation if an error occurs. For example, assume a certain number of bolts must be set to a specific torque. If that torque level isn’t reached, the part isn’t released for the next step.
Advancements in technology take this idea a step further. Assume a worker is using a tablet or computer for guided instructions. The instructions may not proceed to the next step if an error is present. To continue, the worker must identify and resolve the error.
Packaging and Distribution Applications for Poka Yoke
Poka yoke presents a number of interesting opportunities in the packaging and distribution world. In a fulfillment operation, barcode technology can be used to track inventory. A computer system tells the employee which items to pick, one at a time. The employee doesn’t need to track a long list. Rather, he or she simply needs to look for the item displayed at that moment. When that item is scanned, the system moves to the next item.
Parts can be bundled to drive efficiency later in the process. At Deufol, we often do this for our industrial customers. They are shipping parts, products, and tools to project sites. We bundle the parts and products specifically for workstations or tasks. Then, when the bundles arrive, the worker has exactly what they need for their specific job — no more and no less.
Photo documentation software can serve as a poka yoke strategy in packaging. We can store pictures of all products and then use our system to show packers exactly which products should be in which containers. The team verifies that containers have been packed correctly by matching each part with its corresponding picture.
Another poka yoke application is the use of in-line check weighers. The tool is programmed with the specific weight of the items being packaged. If a package’s weight doesn’t align with the expected weight, the team is notified that an item is missing or that there are too many items in the container. Even on items as small as a thermoform blister, weighers can be used to catch mistakes in-line.
The possibilities for poka yoke applications in packaging, fulfillment, and distribution are nearly endless. Mistakes happen. As Shingo learned long ago, everyone makes errors, not just “idiots.” You can minimize those errors, improve your quality, and cut costs by implementing poka yoke strategies into your processes.