THE IMPACT OF WORLD-CLASS MANUFACTURING PRACTICES ON SMALL MANUFACTURERS - by
David K. Johnson

Control Charts

Control charts are one of the most commonly used tools. These charts are constructed by plotting the output of a process on a graph. By using this plot to monitor the output of the process, those involved are able to identify changes within the process, such as a worn or broken tool. This results in a deeper understanding to the process and its natural variation.

Pareto diagrams

Pareto diagrams are some of the most simple, yet affective tools available for the use in quality improvement. These diagrams are based on the idea of the 80/20 principle, which states that “80% of the problems (nonconformities or defects) are created by 20% of the causes.” By identifying and focusing on the important 20 percent, management is able to focus efforts where the greatest impact can be achieved.

Process Capability Analysis

There are two common measures of process capability: Cp and Cpk. These measures compare the variation within the output of a process with the specification limits for the product being produced. Or in other words they simply measure a process’s capability to produce what was designed. Cp is a ratio, which equals six standard deviations of the measured output divided by the tolerance range. Cpk is similar to Cp except for that it takes into account the fact that many processes are not adjusted so that the output mean is centered between the specification limits. These measurements are particularly useful when evaluating different equipment and processes.

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Copyright © 2005. David K. Johnson. All Rights Reserved.