Analysis of an unreliable series-parallel production system with limited storage capacity

Abstract: This paper addresses a new analytical approach to evaluate the throughput of a buffered two-workstation manufacturing system with unreliable parallel machines. The parallel machines are not necessarily identical. The failure, repair and processing times of each machine are assumed to be exponentially distributed. The proposed method is based on two steps. The first step consists of transforming each group of parallel machines into an equivalent one using different replacing techniques. The second step consists of evaluating the throughput of the obtained two-machine-one-buffer model using an equivalent machine method. This method is based on the analysis of the different states of each the buffer using a dedicated birth-death Markov process. Also, some important theoretical proprieties are established. A comparative study based on different test instances issued from the literature is conducted. The obtained results prove the effectiveness and the accuracy of the proposed method.