Shigeo Shingo Essay, Research Paper

Shigeo Shingo revolutionized the manufacturing world with his developments of the Poka-Yoke (pronounced POH-kah YOH-kay) system, and the SMED (Single minute exchange of die) system. POKA-YOKEDuring a one-day conference sponsored by Hewlett-Packard, Shingo, a highly regarded consultant from Japan, was a keynote speaker at the show. He told a story of his trips to Taiwan which is known for its sweet bananas. Shingo enjoyed them so much that he buys a bunch of them everytime he visited there. He realized that, even though he only eats the fruit, not the skins, the shopkeeper was charging him for both. The bunch of bananas weighed 2.8 kilograms, but without the skins, only weighed 1.6 kilograms. He became determined to go to the shopkeeper to get his money back for all the wasted skins. The next day he returned to the factory he was working in and told his supervisor he would try to get some of his money back. However, the supervisor warned that this would make the shopkeeper angry. Shingo conceded and agreed not to ask for a refund, since the shopkeeper had no control over how bananas are made. (Gallagher, p100) This led Shingo to question what banana skins would be considered to be in a factory, and how the banana skins can be eliminated. Banana skins are anything that does not add value to the product.Poka-Yoke can be generally translated as mistake proofing or fail-safing. This system is defined to be a mistake-proof manufacturing system, and a technique for avoiding simple human error at work. By using inspection as an active part of production, errors are identified before they become defects. Production is either stopped until the error is corrected, or it carries adjustment to prevent the error from becoming a defect. Defining the root of an error, and preventing it from reoccurring at the source, is the principle of the JIT production system. Shingo argued that SQC methods do not prevent defects because the information provided tells us probabilistically when a defect will occur, but that is after the fact. The main idea is the difference between errors and defects. Defects occur when people make errors. Therefore, even though errors can happen, defects can be prevented if feedback leading to corrective action takes place right after the errors are made. Feedback comes from inspections, which should be done on 100% of the items produced. There are 3 types of inspections: successive check, self-check, and source inspection. Successive check inspection is either done by the next person in the production process or by a group leader. The worker gets any feedback on defects immediately, and can make repairs. Self-check is performed by the individual worker. This type of inspection is suitable for all but items that require sensory judgement, like correct matching paint shades. Source inspections are also performed by the individual worker. Instead of checking for defects, the worker checks for errors that will cause defects. This prevents defects from occurring in the first place and reduces the need for rework. All of these inspections rely on Poka-Yoke controls, which includes things like checklists or special tooling that prevents errors before starting a process, or gives quick feedback to the worker in time to correct errors. One example of a Poka-Yoke is a device on a train track that will trip the train s emergency break if the driver runs a red light. Another example is an electronic device that will stop a labeling machine from continuing to apply labels if the machine jams and does not apply a label within a certain amount of time.

SMED SMED refers to techniques for reducing the amount of time required setting up production to less than ten minutes. There are two types of setup, internal and external. Internal setups, such as mounting or removing dies, can only be performed when a machine is stopped. External setups, such as transporting old dies to storage or bringing new dies to the machine can be done while the machine is in operation. There are four steps in the setup procedure. The first step is preparation, after-process adjustment, and checking of materials. In this step, all the parts and tools are checked to make sure they are in place and working properly. This step also includes cleaning the machinery, and removing items and returning them to storage after the machine is used. The second step involves mounting and removing blades, tools, and parts before and after processing. This also includes attaching parts for the next lot. Step three concerns all of the measurements and calibrations made before operation, such as centering, dimensioning, and measuring temperature or pressure. The final step is testing and adjusting the machine. This is the most complicated step because many of the problems in the setup lie in adjusting the equipment correctly. Setups can be improved in three stages. First and foremost, a difference must be established between internal and external setup. Workers should have the parts and maintenance, etc., prepared before the machines have stopped. This can cut down normal setup times by 30-50%. (Shingo, p29) Second, a number of operations that are performed as internal setup can really be external setups. Operations should be re-examined to see if any steps are wrongly assumed to be internal. Managers should then find ways to convert these steps to external setup. One example is to preheat elements that used to be heated only after the setup has begun. By using these procedures, defects and reworks can be virtually eliminated, and setup times drastically shortened.

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