RICOH manufacturing DX Practical Lab
What is "Poka"?
The cause and counter measurement of mistakes in manufacturing sites.
Operational mistakes in manufacturing sites may come in numerous forms and causes. The impact of each mistake can range from minor to major. Though, even minor mistakes, may escalate into significant issues when they are ignored.
One of the most common types of mistakes in the manufacturing industry are human errors. In this column, we will explain what human errors are, their causes, and how to deal with them, using actual examples. Those in charge of countermeasures against mistakes are encouraged to refer to this column.
“Poka” in poka-yoke, is a term originally used in the Japanese game board, Igo and Shogi. It’s meaning is to “make an unusually poor move”, which may also be paraphrased as “careless mistakes”.
When used in the manufacturing industry, it refers to “various mistakes caused by carelessness” and so on. Poka include misreading slips or work instructions when receiving goods, picking up wrong parts or wrong quantity of materials, mixing up foreign materials or models, incorrect adjustment of jigs and tools, skipping necessary work or processes, mistaking processes, machine operation errors, and miss detecting items during inspection.
There are various types of mistakes for each process. It is important to take poka-yoke to counter such mistakes as they often lead to product defects, manufacturing equipment failures, work accidents, and complaints from customers.
The primary causes of mistakes are human errors and unfavorable work conditions. Small misunderstandings and misimpression among workers may cause mistakes such as miss-pressing manufacturing equipment buttons, omitting necessary procedures, and confusing production processes for inspection processes.
Mistakes can cause issues like contamination, incorrect assembly, unprocessed parts, and missing products. Sometimes, workers may correct mistakes immediately, without alerting anyone else about it.
Outside of human errors, work and facility environment are potential causes of mistakes. Disorganization of tools and parts at work sites may lead to errors and decreased efficiency. Failing to store tools and parts may result in workers dropping and breaking items, and furthermore, may injure workers.
The lack of sufficient light in the working area increases mistakes. In addition, extreme temperatures may affect both the worker’s hand grip strength and the focus, and function buttons with similar shapes, different functions may cause workers to press wrong buttons. Furthermore, complex operating methods pose a higher likelihood for mistakes in operation of production devices.
The following five steps are necessary to prevent mistakes in the manufacturing industry.
There are various causes of mistakes. Therefore, the first thing that is necessary in introducing countermeasures against them, is to clarify the causes. Since most assembly mistakes are caused by human errors, we tend to assume that workers are the cause for every mistake.
Though, we must take it into consideration that the work environment and the status of the equipment may also be a cause for mistakes. The consequences of the same human errors can vary greatly depending on whether they stem from wrong instructions or from misunderstandings. To pinpoint the cause accurately, it is essential to conduct a thorough analysis.
Once the causes are identified, work procedures can be changed, and new procedures to prevent mistakes may be established. For example, a new confirmation process can be added in areas where mistakes occur frequently, or instructions can be revised to ensure that they are reliably conveyed. Whenever procedures are changed or created, be sure to reflect the changes in manuals and other documents to create an environment in which “the same work results may be achieved no matter who performs the work. If the cause of the mistake is in the facility or environment, we must approach the environment. Specific measures vary widely depending on the cause. Therefore, it is vital to conduct work tests to determine what specific improvements are effective.
After identifying the cause of the problem and implementing countermeasures, it is necessary to ensure that all workers and other concerned parties are aware of the details of the countermeasures. If work procedures or the environment have been changed, it is also advisable to verify that there are no problems with the changed procedures. It is also important to check daily whether work procedures, etc. are being followed correctly and to raise workers' awareness of the importance of preventing mistakes.
As mentioned above, the causes of mistakes in the manufacturing industry can be broadly divided into those caused by human operators and those caused by the work and facility environments. By taking appropriate measures to address the causes, we may create a system to effectively prevent them.
Human errors are unintended consequences of inadvertent human actions, such as “not doing what should be done” or “doing what should not be done”. Simple numerical input errors, picking errors, etc. fall into this category. To prevent such human errors, it is advisable to establish a workplace system with the following in mind.
Examples of concrete measures to achieve these goals include posing pointing and calling on sites and automating procedures through robots.
The Ministry of Health, Labor, and Welfare (MHLW) recommends the use of pointing and calling as an effective means of raising the level of awareness and improving the accuracy of confirmations.
In addition, automation of work by introducing robots will fundamentally reduce human manual work. Although an initial investment is required, it can be an effective means of reducing human error to zero.
The work environment mainly includes noises and disturbed 5S, and the facility environment mainly includes defective equipment. We recommend that you start by reorganizing the essences of the 5S as an easy way to start poka-yoke. 5S stands for “Seiri,” “Seiton,” “Seiso,” “Seiketsu,” and “Shitsuke. By improving these 5 factors, we may keep the work site organized and tidy, and equipment maintained. This shall help prevent human error from occurring.
Mistakes can also be efficiently prevented using the latest digital technology. The work support camera system “RICOH SC-10A” developed by our company is a camera system that automatically checks the assembly status of similar parts, missing parts, and work order by pattern matching of images using image recognition technology.
Since the system prevents workers from proceeding to the next operation unless the former process is proceeded correctly, work errors can be suppressed, and even inexperienced workers can work efficiently and with stable quality. Since the camera is an all-in-one system with all applications built into the camera itself, it can be introduced simply by preparing a monitor, keyboard, and other equipment. The camera can automatically collect information such as serial numbers of parts, images of the assembly state, and working hours during the process, enabling IT-based work analysis and traceability, contributing to DX at the manufacturing site.
The system can be applied to various manufacturing processes, such as checking for over/shortages of parts and similar parts in the picking process, checking work procedures and missing parts in the assembly process, and batch checking for installation errors in the inspection process, to prevent errors.
Work Assistance Camera System SC-10A
We conclude by presenting two manufacturing sites where the implementation of the SC-10A led to a decrease in mistakes.
Fujifilm Techno Products Corporation, a medical device manufacturer, is the first case. Skilled workers have predominantly produced the company's medical devices. Now, due to a recent succession of personnel changes, unskilled workers must manage the manufacturing process.
To address errors causing defects and human labor dependence, the company implemented the SC-10A system for automatic screw tightening order and torque checking during incubator unit manufacturing for blood testing equipment. The system was built. 100% work errors reduction is achieved once an NG error is detected by the system. The system enables a shift in focus from error prevention to productivity enhancement.
This text discusses Ono Sokki Co.'s case.
To manufacture measuring instruments for various applications, this company aimed to reduce errors by implementing a system that minimized dependence on individual workers. A torque screwdriver was connected to the SC-10A, integrated into the DS-5000's assembly process, for detecting overlooked screw tightening. Recording the torque-up signal enhanced traceability for verifying adherence to the specified torque value. With the implementation of the SC-10A, checks can now be conducted thoroughly at required points without the need for supervisor intervention. A system has been established for parallel processing, enabling multiple workers to carry out the same task independently.
Find more information about the case study by clicking below.
Customer usage case: Fujifilm Techno Products Co.
Customer usage case: Ono Sokki Co.
