Use Poka-Yoke to Rest Easy
The purpose of Six Sigma is to reduce defects to an acceptable level more consistently. This can be accomplished with a focused attention and everlasting drive toward improving the quality of the processes that are used during manufacturing and other aspects of the business. Unfortunately, even the most lean and highest quality processes have one unavoidable, detrimental flaw. We are only human, and mistakes will always be made. But there is hope, as there is a certain lean tool that may actually assist in removing the human error factor from the equation. While it is impossible to completely eliminate the possibility of removing mistakes from the workplace, it can be possible to make the probability of them occurring so low, that they are virtually impossible. The technique of mistake proofing a process or workstation is called Poka-yoke, and is one of the most effective ways of reducing the number of defects over the course of time. The basic premise of the practice is that the process or conditions involved are designed in such a way that it is virtually impossible for a human, no matter what amount or training or background, to make a mistake when attempting to perform the task. If the quality manager, or any manager for that manner, of a plant or process starts noticing an unexplained increase in the number of defects in a part of a process, the answer may lie in Poka-yoke.Another way to approach the decision to use Poka-yoke is by interviewing the workers themselves. Frequently they have anecdotes that outline how easy it is to make mistakes that can only be classified as mistakes. Additionally, you can audit your processes and identify certain elements that are critical to quality (CTQ), or have CTQ characteristics associated with them. These are perfect candidates for mistake proofing because a flaw in a CTQ can be detrimental to the entire product‟s performance. The key attribute behind mistake proofing is to keep the processes simple, and anticipate the locations in the process where the mistakes are most likely to happen. Then you can use methods like shaping tools and putting tools on lanyards so that the mistakes cannot happen without the blatant change of the tool‟s function or scope. Let‟s use an example of a manufacturing plant that is piecing together a piece of electronic equipment to place on board locomotives, as can be seen in the “before” section of Figure. The electronic piece of equipment has a cover that must be installed using a grounded screwdriver, in order to prevent the discharge of static electricity into the card.
![[Pokayoke.jpg]](https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjdzCQnMbVn-NraggUJaFOyh9_JEOk-XUi3GaJSSVcaRZVTbmQxKAqCshmtbHocarpQcjtmTI1aS3xPjrsoM1TnEWlu2NsH5im1hF8bgycKPcfBuGdMI6_s8PNDX3OWBXieUpK3yK_3Kq8/s640/Pokayoke.jpg)
A manager started realizing an increasing trend in the breakdown of quality of the results that the electronic equipment was putting out. The voltages that were being produced were going out of specification much more frequently than before, and the manager decided to investigate. She found that the erroneous output was a function of a card that is installed by a workstation on the other side of the line from where the covers are installed. At first, it appeared that there was a severe manufacturing defect in the cards and the workstation that was producing the card. The manager decided to take a closer look, or a “deep dive” and find out through a “fish bone diagram” and root cause analysis what all of the possible causes of a faulty card could have been. After this was done, she realized that there was a possibility the cover was not being installed properly. It was this time that she monitored the worker installing the covers. 1 out of every 5 times, the worker used a screwdriver that was not properly grounded. This is shown in Figure in the “before” section, where the worker becomes confused with which tool to use. Her immediate reaction was that this worker was being careless, or was not properly trained in the process that he was conducting. Because she was a good manager, she asked the worker why he didn‟t use the properly grounded screwdriver. The worker had explained to her that he thought he was using the correct screwdriver, since the both the grounded screwdriver and un grounded one were on a lanyard and looked exactly the same in every other respect. Employing Poka-yoke, the manager shortened the lanyard for the un grounded screwdriver such that it could not be brought to the workstation that installed the cover on the equipment without cutting the lanyard, as can be seen in the “after” section of Figure. By doing this, she made it virtually impossible to use an ungrounded screwdriver to install the cover in question, and in doing so dramatically increased the quality of the product.
As stated before, Poka-yoke is not just for managers and business executives. If instilled properly, every worker and employee of the company should be properly trained in the best methods of mistake proofing, and should provide input on how to eliminate the factor of human error. Mistake proofing is the most effective, and usually the most cost effective, way of increasing quality.
The human element is always a variable in every quality equation, but with Poka-yoke, the impact of that variable can be reduced to a mere fraction of a percent of occurrences than if it were never employed.
The purpose of Six Sigma is to reduce defects to an acceptable level more consistently. This can be accomplished with a focused attention and everlasting drive toward improving the quality of the processes that are used during manufacturing and other aspects of the business. Unfortunately, even the most lean and highest quality processes have one unavoidable, detrimental flaw. We are only human, and mistakes will always be made. But there is hope, as there is a certain lean tool that may actually assist in removing the human error factor from the equation. While it is impossible to completely eliminate the possibility of removing mistakes from the workplace, it can be possible to make the probability of them occurring so low, that they are virtually impossible. The technique of mistake proofing a process or workstation is called Poka-yoke, and is one of the most effective ways of reducing the number of defects over the course of time. The basic premise of the practice is that the process or conditions involved are designed in such a way that it is virtually impossible for a human, no matter what amount or training or background, to make a mistake when attempting to perform the task. If the quality manager, or any manager for that manner, of a plant or process starts noticing an unexplained increase in the number of defects in a part of a process, the answer may lie in Poka-yoke.Another way to approach the decision to use Poka-yoke is by interviewing the workers themselves. Frequently they have anecdotes that outline how easy it is to make mistakes that can only be classified as mistakes. Additionally, you can audit your processes and identify certain elements that are critical to quality (CTQ), or have CTQ characteristics associated with them. These are perfect candidates for mistake proofing because a flaw in a CTQ can be detrimental to the entire product‟s performance. The key attribute behind mistake proofing is to keep the processes simple, and anticipate the locations in the process where the mistakes are most likely to happen. Then you can use methods like shaping tools and putting tools on lanyards so that the mistakes cannot happen without the blatant change of the tool‟s function or scope. Let‟s use an example of a manufacturing plant that is piecing together a piece of electronic equipment to place on board locomotives, as can be seen in the “before” section of Figure. The electronic piece of equipment has a cover that must be installed using a grounded screwdriver, in order to prevent the discharge of static electricity into the card.
A manager started realizing an increasing trend in the breakdown of quality of the results that the electronic equipment was putting out. The voltages that were being produced were going out of specification much more frequently than before, and the manager decided to investigate. She found that the erroneous output was a function of a card that is installed by a workstation on the other side of the line from where the covers are installed. At first, it appeared that there was a severe manufacturing defect in the cards and the workstation that was producing the card. The manager decided to take a closer look, or a “deep dive” and find out through a “fish bone diagram” and root cause analysis what all of the possible causes of a faulty card could have been. After this was done, she realized that there was a possibility the cover was not being installed properly. It was this time that she monitored the worker installing the covers. 1 out of every 5 times, the worker used a screwdriver that was not properly grounded. This is shown in Figure in the “before” section, where the worker becomes confused with which tool to use. Her immediate reaction was that this worker was being careless, or was not properly trained in the process that he was conducting. Because she was a good manager, she asked the worker why he didn‟t use the properly grounded screwdriver. The worker had explained to her that he thought he was using the correct screwdriver, since the both the grounded screwdriver and un grounded one were on a lanyard and looked exactly the same in every other respect. Employing Poka-yoke, the manager shortened the lanyard for the un grounded screwdriver such that it could not be brought to the workstation that installed the cover on the equipment without cutting the lanyard, as can be seen in the “after” section of Figure. By doing this, she made it virtually impossible to use an ungrounded screwdriver to install the cover in question, and in doing so dramatically increased the quality of the product.
As stated before, Poka-yoke is not just for managers and business executives. If instilled properly, every worker and employee of the company should be properly trained in the best methods of mistake proofing, and should provide input on how to eliminate the factor of human error. Mistake proofing is the most effective, and usually the most cost effective, way of increasing quality.
The human element is always a variable in every quality equation, but with Poka-yoke, the impact of that variable can be reduced to a mere fraction of a percent of occurrences than if it were never employed.
Prepared By: Md. Tarikul Islam
01912885383
jonytex073@gmail.com
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