09-11-2016, 04:23 PM
1468123708-Chapter8.ppt (Size: 1.32 MB / Downloads: 6)
Measurements are simply classified as acceptable or not acceptable (pass-fail, or go-no go).
The P Chart
The p chart is the most commonly used attributes chart.
The value p is the fraction or percent, of the number of items checked that are defective.
Application of the Charts
Example
The first case,
Reduced amount of fraction defective - .007
Test of Sample circuit board - 700
The proportion of defective circuits in each sample (p Chart)
The number of defective circuits in each sample (np Chart)
Preparation of the p Chart
Establish an environment suitable for action. (Trainer)
Define the process. ( Charts)
Determine the most promising characteristics to be managed.
Define the measurement system. (pass-fail, go-no go)
Minimize any unnecessary variation before the charting begins. (eliminate the obvious problems)