Control Charts for Monitoring the Reliability of Multi-State Systems. (Dept. M ( Production ) )

Abstract

Control charts are widely used tools for monitoring process behavior. However, for high-quality processes, using traditional Shewhart control charts is not appropriate. Thus, several types of control charts have been established for monitoring high-quality processes based on the Exponential and Weibull distributions. These charts were later adopted for reliability monitoring. So far, these charts have been dedicated for monitoring the reliability of binary-state systems, which have only two levels of performance-functioning or failed. On the other hand, multi-state systems exhibit different levels of performance. This paper introduces two new types of control charts for monitoring the reliability of multi-state systems. Both types monitor can monitor different state transitions with different rates using the same control limits. The first type is the Angular Limits Control (ALC) chart. The ALC chart depicts different system-state distinctively but with the same probability control limits. To achieve this, the chart uses probability control limits with different angles of inclination. The second type is the Transformed Exponential Control (TEC) chart. The TEC chart uses a transformed form of the Exponential distribution as a model for the time to fail.