COMMERCE 4OB3 Chapter Notes - Chapter 3: Crystal Computing
3 Feb 2012
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Document Summary
Sigma limits are the number of standard deviations. Used when not possible to compute the proportion defective and the actual # of defects. Which time a sample of a group of items is taken from the process, the mean is computed and plotted on the chart. Difference b. w. smallest and the largest values in a sample. The x and r charts are used together when both the process and th variability must be in control for the process to be in control. In zone a or b on one side of center line. Process capability: natural variability in a process -> measure with control charts. Ratio of the range of the design speci cations to the range of the process variation. Process capacity index( : indicates the if the process has shifted away from the designed target: > 1. 00 -> process is capable of meeting speci cations, < 1. 00 -> mean has moved increasing amount of defects.
