Poka-yoke is an eternal theme in on-site work, especially in the manufacturing industry. What is the purpose of poka-yoke? We will introduce the meaning and purpose of poka-yoke, which is undergoing major changes due to the innovation of digital technology, as well as the technologies and corporate examples that are being used.
What is "Pokayoke"?
What does Poka Yoke mean, and what purpose did it serve? Let's take a look at its meaning and the concept behind it.
Measures to avoid careless mistakes
On-site mistakes can occur due to carelessness or oversight, leading to defects and equipment failures. These human errors, which would not occur if normal work procedures were followed, are called "Poka," and measures to "avoid" these Poka mistakes are called "Poka-Yoke."
It is said that Poka-Yoke was first adopted by various industries, including manufacturing, through Toyota's improvement activities. It is still used today as a way to ensure quality in the Toyota Production System, and this concept is widely recognized as "Poka-Yoke" in manufacturing sites around the world.
Poka-yoke Concept
Poka-yoke is not fundamentally about improving people's awareness, but about putting in place a system to prevent mistakes caused by factors other than humans. In the first place, if mistakes could be eliminated by simply alerting people to "be careful not to make mistakes," then there would be no need for poka-yoke.
Poka-yoke is a measure to prevent human "carelessness" or "inattention" by using tools to prevent mistakes, establishing rules and work procedures, and introducing new technology. Because it is a system that takes measures against factors other than humans in the work process, it basically aims to ensure that the burden on workers does not change before and after its introduction. Rather, it can eliminate full inspections and multiple checks that were previously performed due to mistakes, which also reduces the burden on workers.
The purpose of Poka-yoke
The objectives of Poka Yoke can be broadly divided into three areas:
- Increased Productivity
- Quality Control
- Ensuring work safety
Let's take a look at how these three relate to Poka Yoke.
Increased Productivity
In order to improve the efficiency of the production process, it is important to reduce the number of defective products and increase production volume. Fewer defective products can reduce wasted time and costs. It is not uncommon for a company to produce a series of defective products because it forgot to do a certain task in a specified work method. In addition, reducing downtime in the production process is also necessary to increase production volume. A typical example of downtime caused by mistakes is when a machine used in the manufacturing process stops because the settings are accidentally incorrect, and it takes a long time to restart the machine. Reducing the occurrence of such defects and the time when production is not possible leads to improved productivity.
Quality Control
It is inevitable that a few percent of defective products will occur during the product manufacturing process. It is extremely difficult to reduce the defect rate to 0%, but what is important at this time is to quickly and reliably discover any defective products that do occur, and quickly remove them to prevent them from being distributed. In order to prevent defective products from being distributed on the market, strict quality control must be carried out at each stage of the manufacturing process. This is not limited to the manufacturing process. Quality inspections of raw materials when they arrive, and managing changes in quality during storage and transportation will also help eliminate "unexpected defects" = "mistakes."
Ensuring work safety
At work sites, there are cases where a single mistake can lead to a major accident. In such work, thorough measures to prevent mistakes are required to ensure the safety of workers. Poka-yoke is also important as an initiative to protect the safety of workers at work sites and prevent industrial accidents.
Four points and three steps for Pokayoke
We will introduce four important points to remember when implementing Poka-yoke, and three steps necessary to implement Poka-yoke.
Four important points for Poka-yoke settings
It is believed that mistakes occur mainly for the following four reasons:
- There is a lack of awareness
- Lack of standards
- The standards are not adequate
- Lack of knowledge, skills and aptitude
When carrying out Poka Yoke, by analyzing the work based on the above four points and listing any shortcomings, it becomes easier to see what measures need to be taken.
Poka-yoke can be thought of in three separate steps
It will be easier to implement measures when thinking about the timing of Poka Yoke if you break it down into three chronological steps.
- Measures before defects occur
- Measures to be taken when defects occur
- Measures to be taken after defects occur
Measures to be taken before defects occur include considering and evaluating the risk of defects occurring, and taking technical measures to prevent mistakes. We also consider mechanisms and rules to prevent mistakes from going unnoticed and moving on to the next process.
Measures to be taken when defects occur include mechanisms to detect defects and mechanisms to immediately notify of detected defects. From the perspective of ensuring safety, we take measures by introducing mechanisms to stop machines or disable their operation if an abnormality that could lead to danger occurs. After defects occur, a mechanism is required to reliably prevent the outflow of defective products. In addition to clarifying inspection rules, we put in place mechanisms to detect defects and eliminate them.
Technologies used for Poka-yoke
In recent years, digital technology has come to be used for Poka-yoke. Three technologies in particular are expected to be highly effective when used for Poka-yoke: IoT, AI, and edge computing. What effect do each of these technologies have when used for Poka-yoke?
IoT
IoT, which can connect any object to a network and receive data, can be said to be a technology that has brought about major changes in the area of poka-yoke countermeasures. Data detected by sensors can be used to instantly detect abnormalities. IoT can be used to detect abnormalities in the workbench on which the workpiece is placed and even the tools used for work, making it possible to take various poka-yoke countermeasures for every move made by workers.
AI
Traditionally, the tasks of "judging" and "distinguishing" were something only humans could do. However, the advent of AI has changed this. By utilizing AI, it is possible to give machines the ability to "judge" instead of humans. For example, technology that uses AI to identify defective products from visual information obtained through a camera is already being introduced. By utilizing AI to automate the process of detecting defects and anomalies, it is also possible to automate and improve the accuracy of error prevention.
Edge Computing
Poka-yoke is important for preventing defective products from being sent to the next process by instantly notifying mistakes that occur due to "carelessness" or "inadvertence". Edge computing contributes greatly to the real-time detection of such mistakes and notification. Edge computing assigns whether data is processed by a computer located close to the site or a computer located far away, such as a cloud service. This enables faster processing. Faster processing improves the real-time nature of the data obtained or the commands issued after processing.
When using IoT or AI for poka-yoke, network delays may delay the detection of defective products or the notification of abnormalities. In addition, it is possible that the poka-yoke system will become unusable due to network connection abnormalities or cloud service downtime. These problems can be avoided by distributed processing with edge computing. It can be said that the value of using edge computing for poka-yoke is high in terms of speeding up processing, improving the real-time nature of data, and ensuring operational continuity.
Examples of Poka-yoke implemented by companies
In fact, here are some examples of companies that are working on Poka Yoke:
Poka-yoke with IoT tools
In tasks that use tools, whether or not the tools are used properly can detect the occurrence of procedural errors that can lead to careless mistakes. Poka-yoke can be achieved by using the right tools, such as tightening with a torque wrench or crimping terminals with a crimping tool. One measure is to attach a sensor or transceiver to the tool to notify if a workpiece passes by without using the tool, or if the tool is used in a different procedure.
Poka-yoke with image processing systems
Poka-yoke, which uses image processing systems to detect mistakes, is being increasingly introduced at manufacturing sites. For example, it is possible to measure the color area within a detection range from an image captured by a camera and detect forgotten or misaligned colored parts. With the development of image processing systems, machines can now automatically judge and distinguish things that were previously judged by the human eye, making it possible to widely use this system as a form of poka-yoke.
Poka-yoke system that fully supports cell production
In cell production, where one person or a small team of workers is responsible for the entire assembly process, the impact of careless mistakes is greater due to the small number of workers. This is why support systems that perform poka-yoke (error
prevention) are attracting attention. The screws to be used in the next task are displayed on the interface, and a camera is used to recognize the screws and parts taken from the parts tray. If a different part is taken than instructed, an alarm is sounded to prevent careless mistakes. The system also judges the torque used when tightening the screws and the quality of the part installation. Accumulating and analyzing this data can be used to educate workers and review designs.
Combining Pokayoke with digital technology provides a more advanced level of mistake prevention measures
Various methods of Poka-yoke have been researched, but with the recent spread of IoT, the practical application of AI, and the combination of these with edge computing to speed up and stabilize it, developments in digital technology have also caused major changes in Poka-yoke methods. Traditionally, Poka-yoke was centered on education, signs, and manual preparation, but the use of digital technology is becoming mainstream, making it possible to prevent mistakes with even greater precision. It can be said that innovation is also occurring in Poka-yoke through the application of digital technology.
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