Time-between-events charts for on-line process monitoring

Abstract

With the development of automation and high-quality manufacturing techniques, on-line process monitoring system has become essential for enterprises to ensure product quality and reduce cost. This paper presents an on-line process monitoring system which provides the users with different charting methods to monitor time-between-events data, and detect process shifts. Some advanced time-between-events control charts, such as Cumulative Quantity Control (CQC) chart, CQC-r chart, exponential EWMA and exponential CUSUM chart are discussed. Comparisons of their performance are carried out based on Average Time to Signal (ATS). The design of an on-line SPC system is described, followed by an application example. The approaches presented in this paper complement other on-line systems and can be integrated into existing systems easily. (c) 2004 IEEE.