Quality Control Chart Design And Economic Studies

Nowadays 3~σ principle is commonly used in domestic corporations and overseas. However it is in great trouble to control the quality of process with control chart because the total cost arose by Type I and Type II errors could not achieves minimum level. The paper indicates that if we want to use control chart economically we should firstly work out the design of the economic control chart. Most important work is to obtain the sample size, sampling period and confirm the control limits. The paper thus builds the mathematical model of the control chart that corporations could get great use of it to control the process.This article, taking the X char as the example, expatiated upon Average Run Length (ARL), which was common used in modern quality control. Then presents the idea of Average Produce Quantity (APQ), which is the advanced way to design a model in order to obtain the parameters of control char. It also presents that when quality characters are in the situations such as the normal distribution and non-normal distribution how to apply the APQ model in quality control.On the other hand, this paper proposes methods for determining the optimal choice of design parameters for the multivariate exponentially weighted moving average (MEWMA) control chart. Evaluating the ARL values for the MEWMA chart through simulation, we determine optimal chart parameters given cost information.In the end, the model is developed to a way to common use to all kinds of control chars. Through the model we can obtain the parameters of control char in order to make quality control in a convenience, economic way.