Application of SPC 3σ Principle to Output Moisture Content Monitoring in Cut Tobacco Drying

In order to make SPC control chart more suitable for quality monitoring in tobacco primary processing line,the reasons causes of higher false alarming rate of traditional Shewhart control chart in primary processing line were analyzed.A 3σ average value control chart was established based on the upper and lower limits of average value control chart,and the application of control chart to the output moisture content monitoring in cut tobacco drying was studied.The results showed that comparing with Shewhart control chart,the 3σ control chart reduced false alarming rate from more than 70% to below 5%.It suggested that 3σ control chart was more applicable to the SPC of tobacco primary processing.