Contact method: The contact method of poka-yoke uses some type of sensing device to identify defects in a part's shape, size, color or other physical attribute.There are three recognized types of poka-yoke that, when implemented, can greatly reduce human errors by effectively making it impossible to make a mistake in a given process. This prevents or highlights defects without the need for any type of judgment inspection or relying on an operator to do something. In this hierarchy, the least effective form of quality control is the use of inspection, while the most effective is using autonomous procedures and poka-yoke devices. Information inspection: using statistical process control (SPC) to monitor conditions within the process.Judgment inspection: inspectors inspect products.Shingo viewed quality control as a three-level hierarchy of effectiveness that includes poka-yoke: Poka-yoke strives to prevent mistakes from becoming defects. Defects are mistakes that manage to make it all the way through a system and reach the customer. He said mistakes are inevitable in most cases but can be detected and corrected immediately. Shingo made the important distinction between mistakes and defects. This is where poka-yoke techniques play a critical role between human error and the causes of defects. Many customers find one defect and return the entire batch of parts out of precaution. The bottom line is manufacturing defective parts usually ends up being very costly. For example, this would include using a digital counter to track the number of spot welds on a product, ensuring the welder makes the correct number of welds before sending it down the line. Shigeo Shingo of the Toyota Production System (TPS) adopted poka-yoke methodologies to be implemented at any step in a manufacturing process where something can go wrong or an error can be made. When the consequences of a mistake are expensive and/or dangerous. When a small error early on in a process can cause a major problem later down the line and With a step in a process involving a hand-off, where output is transferred to another worker (or customer in a service process) In a service-related process where the customer can make a mistake that affects the output When a step in a process is determined to leave room for human error, causing mistakes and defects to occur (this is especially true of steps that rely on the operator's attention, skill or experience) Common areas where poka-yoke works well include: In fact, automatic braking systems are becoming a common feature in most new cars, helping prevent accidents due to human error. They operate by using multiple sensors and alerts like automatic braking and a variety of cameras to "see" everything around them in real time. Self-driving cars are a modern consumer-based example of poka-yoke. Tesla's sensor had automatically detected the hazard and acted (without human input) to avoid a crash. In another more terrifying instance, a Model 3 driver from Florida experienced seemingly inexplicable braking from the Tesla's autopilot feature while traveling at highway speeds, only to find out a split second later that the car in front of them swerved out of the lane to reveal a stopped car. Tesla recently showed a video of its Model 3 backing out of a parking space and slowly maneuvering its way to pick up its owner, who had called it via his smartphone. Self-driving cars are slowly becoming a fairly common sight on the roads. In manufacturing, this means not accepting, creating or allowing defects to move down the line. In Japanese, poka-yoke translates to "mistake-proofing" or "inadvertent error prevention" and was originally described as baka-yoke, which means "fool-proofing." The purpose of the poka-yoke technique is to eliminate product defects by preventing them in the first place, correcting them or drawing attention to human errors as they occur. Poka-yoke (pronounced PO-ka yo-KAY) is the use of a mechanism or device that helps an equipment operator (or anyone) avoid mistakes.
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