Lead Time Dependent Product Deterioration in Manufacturing Systems with Serial, Assembly and Closed-Loop Layout

In several manufacturing systems found in the automotive, food and semiconductor industries, product quality or value deterioration due to excessive residence time in the system are observed. This phenomenon generates defective or low value products, thus undermining the performance of these systems. In this paper, a method to compute the lead time distribution under a wide set of system architectures is proposed. The method is based on the analysis of the probability that a part enters the system in a certain position in the buffer and on the calculation of the distribution of the time to absorption of a Markov chain representing the states of the downstream portion of system. Then, considering a function that expresses how the product deteriorates with the residence time in the system, the main performance measures are derived. Numerical results show previously uninvestigated behaviors of manufacturing systems under lead time constraints and provide insights on the design of these complex systems. In particular, the method supports the optimal selection of buffer sizes to achieve the target effective throughput in these systems.