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Nontraditional Control Charting

Summary: [This abstract is based on the author's abstract.]

There is a need for other approaches for implementing statistical control that will fill the gap between Shewhart's theory and current realities. Relatively new methods such as time-series using exponentially weighted moving average (EWMA) control charts have the potential to address part of this need. A combination of some of the newer methods resulting in dynamic control charts is presented. The trend of process control instrumentation using solid-state sensors and high-speed microprocessors emphasizes the necessity for developing more effective real-time control programs. The dynamic control chart is adaptable to control systems for continuous processes. While classical statistical control methods are satisfactory for long runs of consistent material, many current products are customized through computer-assisted design and manufacturing, which affect the number of runs and the homogeneity of input and output materials. There is a need to be "on target" and "in control" as soon as possible to minimize losses from the production of nonstandard material. "PRE-Control", which was created in 1952, is successful in achieving this goal for discrete items and batch processes.

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  • Topics: Statistical Process Control (SPC)
  • Keywords: Shewhart control chart, Statistical process control (SPC), Time series, Systematic assignable cause, Exponentially weighted moving average control charts (EWMA), Trends, Run length, Variation
  • Author: King, James R.
  • Journal: Quality Engineering