Simultaneous quality and reliability optimization for systems composed of degrading components

Models for determining optimal component specifications limits have been developed considering both quality and reliability of a large system containing degrading components. Specifications on a characteristic of a system are usually determined by maximizing quality performance at the manufacturing phase. However, some systems are designed with components that degrade in time. For these systems, system reliability is a critical measure of the system performance over time. To the benefit of both the manufacturer and the consumer, both quality and reliability over the product life cycle need to be considered when setting initial manufacturing specifications. By rewarding the high system reliability and penalizing the quality loss due to variation, we investigate probability and optimization models to determine the initial process mean, specification limits, and system replacement intervals.