Abstract
There have been a number of studies on process control methods, although these theories are too complicated to be applied to manual control production processes. In these processes, an operator measures an important quality characteristic, and then changes a control variable to adjust the observed deviation in the characteristic. This simple paper proposes an approximate method of calculating a reduction factor for this adjustment using only two parameters of process errors and measurement errors. The degree of approximation in this method is evaluated for three typical types of process errors. The reduction factor calculated by this method has a constant value, while the reduction factors that vary according to the deviation are often used in actual production processes. This paper compares these two types of reduction factors in their control effectiveness. The method of estimating the reduction factors using operation data is also discussed.
