Statistical process control procedure for controlling moisture content in tobacco

Abstract

Moisture content percentage (MC%) in tobacco is a very important quality characteristic. High cut-out or the presence of a lot of moisture in tobacco leads to moldy tobacco-a problem with considerable implications from the standpoint that thrashed tobacco may lie in the stock for up to 3 years before cigarette making. The presence of low moisture in tobacco also leads to unfavorable conditions for cigarette making, although the problem is not as severe as the presence of high moisture in tobacco. This study describes how the variation in moisture content in tobacco was reduced, resulting in a substantial reduction of high cut-out percentage from 20.33 to 1.62% in an Indian tobacco leaf thrashing unit. Since overseas customers from the UK are very particular about not accepting a lot of high cut-out percentage, the study narrates a success story in the procedure of statistical process control implementation for moisture control in tobacco. The statistical techniques used for the purpose are: paired t-test and CUSUM control chart for routine bias correction of moisture measuring instruments and X-MR chart for controlling MC% on a regular basis.