System reliability methods for analysis of process models

Process modeling methodologies have become widely used in defining and analysis of manufacturing systems. Two specific types of models, functional analysis and process flow descriptions, are frequently discussed in the literature. However, most published work presents the basic concepts, industrial applications, and critiques of various methodologies. One drawback often cited is that, beyond preliminary ad hoc analysis, process models are seldom used. Furthermore, the lack of quantitative information in models prevents more detailed and interesting analysis. This paper adapts traditional system reliability methods to manufacturing and design process modeling. The logical relationships between activities in the process are used to quantify the overall reliability of the system and identify high-risk paths of decisions in the process. The concepts of path sets and cut sets are then used to identify critical activities and decision points. The analysis is illustrated with an industrial case study.