Decomposition of unreliable assembly/disassembly networks with limited buffer capacity and random processing times

An assembly/disassembly network is a manufacturing system in which machines perform assembly and/or disassembly operations. We consider tree-structured systems of unreliable machines that produce discrete parts. Processing times, times to failure and times to repair in the inhomogeneous system are assumed to be stochastic and machine-dependent. Machines are separated by buffers of limited capacity. We develop Markov process models for discrete time and continuous time systems and derive approximate decomposition equations to determine performance measures such as production rate and average buffer levels in an iterative algorithm. An improved parameter updating procedure leads to a dramatic improvement with respect to convergence reliability. Numerical results demonstrate that the methods are quite accurate.