Disadvantages Of Fishbone Diagram

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Fishbone diagram is also known as Ishikawa diagram which is created by Japanese Quality Guru named Dr. Kaoru Ishikawa. It looks like a “fish skeleton” and not involving statistics. It maps out a process or problem, makes improvement easier and pictorial representation of all possible causes contributing to a problem. In manufacturing areas, the fishbone diagram is grouped into few major categories which are 6M’s. They are Man, Material, Method, Machine, Measurement and Mother Nature or Environment. The major categories then will be segregated by sub cause. Figure: Fishbone diagram i. Man – anyone involved with the process ii. Material – raw materials, parts, pens, paper, etc. used to produce the final product iii. Method – how the process is performed and the specific …show more content…

Monitoring and controlling the process ensures that it operates at its full potential. An advantage of SPC over other methods of quality control, such as “inspection”, is that it emphasises early detection and prevention of problems, rather than the correction of problems after they have occurred. SPC may be used when a large number of similar items are being produced. Each process is subject to variability. The variability present when a process is running well is called the inherent variability or short term which is usually measured by the standard deviation. Most processes have a target value. The purposes of SPC are to give a signal when the process mean has moved away from the target and to give a signal when item to item variability has increased. In either case suitable action must then be taken by an engineer or a machine operator. Besides, statistics can only give the signal while the action relies on other skills. The most common method of SPC is to take samples at regular intervals and to plot the sample mean on a control

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