Process of validating a will
For example, one operation involves cutting wire into 100 cm lengths. A sample of 12 wires is selected at random and the following results obtained: 98.7 99.3 100.4 97.6 101.4 102.0 100.2 96.4 103.4 102.0 98.0 100.5 A histogram of this data follows.The width of the histogram represents the variation.Control charts, capability studies, designed experiments, tolerance analysis, robust design methods, failure modes and effects analysis, sampling plans, and mistake proofing are but a few.Each of these tools will be summarized and their application in validation described.
Where potential risks exists, the FMEA can be used to document which failure modes have been addressed and which still need to be addressed.For measurable characteristics like wire length, fill volume, and seal strength, the goal is to optimize the average and reduce the variation. Stable processes produce a consistent level of performance. It involves collecting samples over a period of time.Optimization of the average may mean to center the process as in the case of fill volumes, to maximize the average as is the case with seal strengths, or to minimize the average as is the case with harmful emissions. The average and standard deviation of each time period is estimated and these estimates plotted in the form of a control chart.To help determine if the process is capable, several capability indices are used to measure how well the histogram fits within the specification limits.One index, called C, is used to also evaluate the centering of the process.