What is Poka Yoke?
Poka yoke is a Japanese term meaning “avoiding mistakes or errors” and is pronounced as poe-kah yo-kay. Developed by Shigeo Shingo in the 1960s, it is a process improvement technique that significantly reduces the number of defects produced. Poka yoke achieves this by placing barriers against mistakes (i.e. eliminating opportunities for errors to be made).
While the term may not be familiar, everyone practices poka yoke in some form or another in their daily lives. When you wake up really early in the morning to make sure you don’t miss the bus to work, that’s poka yoke. Telling your coworkers before an office party that you’re allergic to shrimp so they know not to put it in the food is also poka yoke.
Poka yoke (or mistake proofing) is, essentially, planning or preparing in advance so that something bad doesn’t happen.
Outside of personal matters, use poka yoke when:
- a process is complicated, involves many steps, or requires a high amount of precision
- a process is prone to causing errors or is extremely unpredictable and/or unreliable
- people who aren’t part of the business but are somewhat involved in the process
(such as a supplier) or can directly affect its outcome (such as a customer in a service-based industry)
- there is a gap between the current skill level of employees and the skill level required to ensure that the process, and the system as a whole, doesn’t run into any problems
- there have been repeated and significant incidences of workers making the same mistake and the other proposed solutions to combat the issue have been ineffective
These are just some examples of when to use mistake-proofing. There may be other situations that call for it but, ultimately, the decision to use or not use poka yoke is up to you and the other stakeholders in your business.
Given that the conditions mentioned in the previous section are what some may call “accidents waiting to happen,” it’s wise to give poka yoke serious consideration and take the time to fully understand the consequences of choosing to not implement it.
Here are the possible effects if situations, such as the ones above, are left unchecked:
- An accident occurs or a vital step is missed due to workers being overwhelmed by the complexity of the process and with too many things needing their attention.
- The entire system breaks down and the processing plant has to remain closed for a number of days, even weeks, because errors added to the unreliability of the process.
- Defects are unknowingly produced since the supplier’s mistake was never detected and, thus, never corrected.
- Problems pile up and workers don’t know what to do. Everyone struggles to keep things running smoothly. Eventually, the workers are asked to resign and management has a hard time finding their replacements since those applying have the same skill level as the ones who were laid off.
- Workers try not to make the same mistake, but slip-ups occur frequently and go unreported because they’re afraid of being reprimanded. The processing plant’s efficiency remains suboptimal and management can’t figure out why.
If you and other stakeholders have decided that poka yoke is right for your business, here’s what you can expect after implementation (in the best-case scenario):
- The process is streamlined, or it hasn’t changed but workers have an easier time completing it now than before.
- The process is more reliable, or it remains unpredictable, but mistakes are caught before any major damage is done.
- Errors committed by third parties no longer affect the quality of the end product since the process is set up in such a way that even minor mistakes are caught.
- Workers are now able to manage their tasks within the process more efficiently since it’s been modified to suit their overall skill level.
- Workers no longer make the same mistake because a warning bell stops them from proceeding to the next step.
One of the key advantages of mistake-proofing is that the process doesn’t always have to change. This is especially relevant to businesses in manufacturing since some of their processes cannot, for either quality or safety reasons, be changed. Changing them completely or replacing them would also take up a lot of time, money, and effort.
But with poka yoke, processes don’t need to go through a drastic transformation to become more efficient.
Digitize the way you Work
Empower your team with SafetyCulture to perform checks, train staff, report issues, and automate tasks with our digital platform.Get Started for Free
If you’re set on implementing poka yoke in your business, or even just trying it out, use this guide to develop a clearer understanding of where it would fit in your process:
Step 1: Find sources of defects
Closely investigate where the defect was first identified. From there, retrace its processing history and note down all the possible points where a mistake could have been made. Note down as well the possible reasons why a person would make that particular mistake.
Once you have finished listing down the sources of defects, select a few of them to prioritize. Choose ones that have a domino effect on other aspects of production or have the biggest impact on the creation of the defect.
Step 2: Choose a method to apply
To help you choose the best overall poka yoke method for your process, refer to the flowchart below:
Also take into consideration the defect sources you have prioritized in the first step. Though choosing one method for each defect source is generally not recommended, there may be special cases where doing so is the best possible option.
If you’re still unsure about which method to apply, hold an open discussion with the workers and/or other stakeholders to get their input for your final decision.
Step 3: Measure its effectiveness using checklists
After you’ve implemented poka yoke, which would look different depending on the method you have chosen, now is a good time to test its effectiveness using inspection checklists. For mistake proofing, there are 3 types of inspections:
SafetyCulture (formerly iAuditor) is an operations management platform trusted by thousands of global brands including Toyota, General Electric, Siemens, and Unilever. Do poka yoke more efficiently with these SafetyCulture features:
Get Ahead with the Issues Feature
Spot the sources of defects instantly by connecting with the factory floor workers on the mobile app. Using the Issues feature, workers can easily let you know if there are any existing conditions that make it harder for them to do the job error-free.
Ensure Accuracy with the Template Feature
Retrace the processing histories of defects with ease. Use a digital template as a guide in outlining the different steps in the process. Add questions, images, notes, and more to your digital template, so that it captures your process perfectly.
Deliver on Performance with Data Analytics
Are defects affecting your bottom line? If so, it may be time to see the bigger picture and not just the minor details. Finding out what needs to be done and implementing those changes only works if you have a system in place.
With data coming in from digital templates, inspection checklists, and the Issues feature, your analytics dashboard in SafetyCulture is supplied with all the info you need to make improvements fast and effectively.