Use statistical methods to monitor the process state, ensure that the production process is under control, and reduce the variation of product quality. SPC can solve the problem of 1. Economy: effective sampling control, no need for full inspection, defective rate and cost control. Make the process stable and master the quality, cost and delivery time. 2. Early warning: abnormal process trends can be taken immediately to prevent the whole batch of defects and reduce waste. 3. Distinguish special reasons: as a reference to solve local problems or improve management system. 4. Make good use of machinery and equipment: estimate the production capacity of machinery, and reasonably arrange suitable machinery to produce suitable parts. 5. Evaluation of improvement: Process capability can be used as an indicator of comparison before and after improvement. Evaluate the process reliably and effectively;
Determine the statistical control limit of the process, and judge whether the process is out of control and whether the process is capable;
Provide early warning system for the process, monitor the process in time to prevent the occurrence of waste products;
The dependence on routine inspection is reduced, and regular observation and systematic measurement methods replace a lot of detection and verification work. The computing power ratio of Pp unqualified (bilateral) Ppk unqualified (unilateral) is 0.50133,620 66,810.6071.860 35. 930 0.70 35,730 17,865 0.80 16,396 8, 198 0.90 6,934 3,467 1.00 2,700 1, 350 1. 10 966 483 1.20 3 18 159 1.30 96 48 1.40 26 13 1.50 7 3 1 .60 2 65438 +0 1.70 0.340 0. 170 1.80 0.060 0.030 1.90 0.0 12 0.006 2.00 0.002 0.00 1