Читать книгу Introduction to Statistical Process Control - Muhammad Amir Aslam - Страница 14

Most of the SPC techniques being used nowadays are the techniques developed during the twentieth century. The control chart technique was basically introduced by Walter A. Shewhart in 1920s during his services rendered to Bell Laboratories. Two types of variations (common and special causes of variations) in the products of the manufacturing units were pointed out in an internal memo of about one page length written by Walter A. Shewhart on 16 May 1924. That one page consisted of text, and one‐third of the page was utilized for the diagram of the shape showing UCL and LCL, which we are using nowadays as control chart. Two renowned quality control experts, connoisseurs, aficionadas, buffs, and polishers of the statistical methods applied to the quality management are Shewhart and Deming who wrote a book, Statistical Methods from the Viewpoint of Quality Control, in 1939, which is helpful and supportive even today as it was then (Oakland, 2008, p. 14). After the defeat of Japan in Second World War, Dr. William Edwards Deming (Shewhart's boss), basically an American statistician, engineer, professor, author, and management consultant, helped Japanese companies to improve the quality of the products by focusing on the monitoring and diagnosing of variability. The causes of variation were focused particularly in the manufacturing industry to improve performance through quality management system and SPC. Many companies in the world adopted the Deming philosophy and attained success swiftly in the years to come. The popularity of SPC for the success of manufacturing industry delivered the message to suppliers of raw material, goods and services providing organizations, and all the companies related to the manufacturing industry about the enormous potentials of the SPC in terms of market share, maximizing profits, and reducing rework of products. As a result a colossal demand for quality control techniques, SPC experts, and utilization of computer technology was created to survive in the world.

In 1935 the British Standards Institution introduced modification as the three‐sigma control limits were replaced with the limits based on the percentiles of normal distribution.

Since the early 1980s, the US industry improved the quality substantially due to theories developed by the researchers. Dr. Genichi Taguchi, Dr. Joseph M. Juran, Dr. Deming, and Philip Crosby assisted the manufacturing industry magnificently for improving the product quality. A new boast was injected to the industry by Dr. Genichi Taguchi by introducing new concepts in experimental design, robust design, and loss function. The quality system of ISO 9000 and QS 9000 was introduced by the United States in the early 1990s.

Most of the emphasis on the execution of the control chart has been seen in the second half of the twentieth century when the monitoring of small shifts in the production process was focused by announcing two methodologies. These methodologies were the cumulative sum introduced by E. S. Page in 1954 and the EWMA by S. W. Roberts in 1965. Another direction was introduced by R. E. Sherman in 1965 when he hovered the idea of repetitive group sampling. The technique of the repetitive sampling was readdressed by S. Balamurali and C. H. Jun in 2006. Currently, a plenty of literature can be seen on the application of repetitive group sampling technique with the major contributions of M. Aslam and L. Ahmad (Ahmad, Aslam, & Jun, 2014; Aslam, Srinivasa Rao, Ahmad, & Jun, 2017).