Modeling and designing control chart for monitoring time-between events data

Abstract

Time-between-events chart is receiving considerable attention because more and more processes are high-yield processes. The focus of this thesis is to improve the existing time-between-events chart by making it more practical, efficient and economical. First, random process shift idea is introduced to the time-between-events chart, which makes the time-between-events chart effective for detecting a wide range of process shifts. Then, preventive maintenance is taken into consideration when designing the time-between-events chart because control chart and preventive maintenance are interrelated. The integrated model of time-between-events chart and preventive maintenance is developed. Finally, the improvement of existing time-between-events chart extends to the time-between-events chart system which consists of several time-between-events chart. Each of the time-between-events charts is used to monitor one process stage in a multistage manufacturing system. Both the statistical and economical model of time-between-events control chart system is developed. And the optimization algorithm for searching optimal control limits is provided.