Walter A. Shewhart Introduction and Contribution
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Walter A. Shewhart is known as the father of statistical quality control and is also related to the Shewhart cycle.
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Walter A. Shewhart Introduction and Contribution
- 1. Walter A. Shewhart Rashna Maharjan & Pratima Khadka
- 2. Background ● Walter Andrew Shewhart (pronounced like "shoe-heart", March 18, 1891 – March 11, 1967) was an American physicist, engineer and statistician, ● sometimes known as the father of statistical quality control and also related to the Shewhart cycle. ● Mr. Shewhart was also awarded his doctorate in physics from the university of California, Berkeley in 1917. ● Mr.Shewhart is also known as a Pioneer and Visionary of modern quality control. ● Mr. Shewhart laid the first seed of the quality movement with his book “Economic Control of Quality of Manufactured Product”. ● His books were used by the Japanese after World War II.with aid of visiting consultants, to help shape modern quality practice in Japan.
- 3. Involved Organization and Progress ● In 1918, Mr. Shewhart joined Western Electric Company Inspection Engineering Company inspection Engineering department. On that time Industry quality was limited to inspecting finished product and remogram, and the short text which preceded and followed it, set forth all of the essential principles and considerations which are involved in what we know today as process quality control.ving defective items but later Mr. Shewhart prepared a memorandum only a page in length for which the page was given over a simple diagram which would recognized today as a systematic control chart. ● Most of Shewhart's professional career was spent as an engineer at Western Electric from 1918 to 1924, and at Bell Telephone Laboratories, where he served in several capacities as a member of the technical staff from 1925 until his retirement in 1956. ● That diagram, and the short text which preceded and followed it, set forth all of the essential principles and considerations which are involved in what we know today as process quality control.
- 4. Shewhart’s Contributions ● Process Improvement Reducing variation ○ Simple schematic control chart ○ No two products will ever be the same two classes of variation, namely special-cause’ and common-cause’ ● Deming Wheel Cycle and Six Sigma ○ PDCA or plan-do-check-act, ○ DMAIC or define-measure-analyze-improve-control ○ More the number of iterations a product is subjected to, the better the end output.
- 5. Shewhart’s Contributions on Industrial Quality ● First task to improve quality was at Nokia Bell Labs ● Engineers at Nokia Bell Labs (Bell Telephone earlier) had been working to improve the reliability of their transmissions systems ○ Reducing variation in manufacturing processes would have a positive impact on repair costs ● Nokia Bell Labs’ discoveries in product variation resulted in the institution of an inspection program, ensuring specification and quality standards to avoid sending defective products to customers.
- 6. Thank You
Editor's Notes
- Shewhart is best known for his simple schematic control chart which changed the manufacturing industry forever. This chart outlined principles essential to modern process quality control. These are followed to this day with certain improvements as production processes became more complicated. A key thing to remember in any process is that no two products will ever be the same. Reducing these variations to improve quality has always been one of the manufacturing industry’s greatest challenges. Dr. Shewhart’s acknowledgment of two classes of variation, namely special-cause’ and common-cause’ led him to improve his control chart mentioned above. He proposed variables which would reduce common-cause’ variations. According to him, to distinguish between the two, every manufacturing process would need to be brought under statistical control. This and other principles of Shewhart helped pave the way for modern analysis of manufacturing processes.
- Business dictated a need to reduce the frequency of failures and repairs to their amplifiers, connectors and other equipment that were buried underground. Bell Telephone had already realized that reducing variation in manufacturing processes would have a positive impact on repair costs. At the same time the company determined that continual adjustments in process parameters reacting to non-conformances resulted in increased variation and a degradation of quality. Bell Telephone’s discoveries in product variation resulted in the institution of an inspection program, ensuring specification and quality standards to avoid sending defective products to customers. Even though this program was somewhat effective, it was very costly to deal with inspecting and sorting of finished goods. By 1924, Shewhart determined the problem of variability in terms of assignable cause and chance cause (Deming referred to this as common cause). On May 16, 1924, Shewhart prepared a memorandum of less than one page in length and forwarded it to his manager, George Edwards. About 1/3 of the page was devoted to a simple diagram that we would today recognize as a control chart. This memorandum set forth the essential principles and considerations that became known as process quality control. Shewhart’s principle was that bringing a process into a state of statistical control would allow the distinction between assignable and chance cause variations. By keeping the process in control, it would be possible to predict future output and to economically manage processes. This was the birth of the modern scientific study of process control.