How to determine the sampling scheme in SPC system?

The sampling method of SPC depends on the analysis object. Different objects have different sampling methods, and different stages of analysis have different sampling methods. Let me explain: 1, the most common is X- bar chart: the key of sampling method is timing sampling, and a group of five samples are averaged; Statistical process capability, sampling at an average interval of 5-30 minutes when the control limit is exceeded, and sampling at an interval of 2 hours when it is stable;

2. A variant of the X-bar chart is a single-value moving range chart. When the sampling inspection will destroy the product or the inspection is difficult and expensive, the sampling method of one inspection per shift will be adopted under stable conditions;

3.P-chart is another commonly used SPC. The sampling method can be to summarize the defective rate of 1 week and 1 month, and analyze the statistical process, the first three items, the reasons and countermeasures. ...

The above are the most commonly used SPC, and the sampling method depends on the analysis object, as do other SPC.