What is spc

SPC is Statistical Process Control (StatisticalProcessControl). SPC mainly refers to the application of statistical analysis technology to real-time monitoring of the production process, scientific distinction between random and abnormal fluctuations in product quality in the production process, so as to put forward an early warning on the abnormal trends in the production process, so that production management personnel can take timely measures to Eliminate the abnormalities and restore the stability of the process, so as to achieve the purpose of improving and controlling the quality.

The use of statistical methods to monitor the state of the process, to determine the production process in a state of control in order to reduce the variation in product quality.

Statistical process control (SPC for short) is a process control tool with the help of mathematical and statistical methods. It analyzes and evaluates the production process, finds the signs of systematic factors in time according to the feedback information, and takes measures to eliminate its influence, so that the process is maintained in a controlled state only affected by random factors, in order to achieve the purpose of controlling the quality. It is believed that when the process is only affected by random factors, the process is in a statistically controlled state (referred to as the controlled state); when there is a systematic factor in the process of the impact of the process, the process is in a statistically uncontrolled state (referred to as the out-of-control state). As the process fluctuations have statistical regularity, when the process is controlled, the process characteristics generally obey the stable random distribution; and out of control, the process distribution will change.SPC is the use of process fluctuations in the statistical regularity of the process analysis and control. Thus, it emphasizes the process in a controlled and capable state of operation, so that products and services to meet customer requirements in a stable manner.

The process of implementing SPC is generally divided into two major steps: first, the process is analyzed using SPC tools, such as drawing control charts for analysis; according to the results of the analysis to take the necessary measures: it may be necessary to eliminate the systematic factors in the process, and it may also be necessary to intervene in the management to reduce random fluctuations of the process in order to satisfy the process capability requirements. The second step is to monitor the process using control charts.

Control charts are the most important tool in SPC. The traditional control charts based on Shewhart's principle are widely used in practice, but control charts are not limited to this. In recent years, the gradual development of some advanced control tools, such as small fluctuations in the monitoring of EWMA and CUSUM control charts, small batch multi-species production process control of proportional control charts and target control charts; control of multiple quality characteristics of the control chart.