Productivity of synchronized serial production lines with flexible reserve capacity

The configuration of a manufacturing system greatly influences its productivity because many configurations have multiple productive states. Flexible reserve production capacity is one method to increase the number of productive states. Reserve production capacity is the provision of non-dedicated standby machines in parallel to the main production line that are capable of performing any operation in the production line. Standby machines, like buffers, isolate failures in the production line, permitting production to continue. This paper develops models to predict the productivity of pure serial and parallel-serial production lines with reserve capacity. Combinatorial mathematics is applied to determine the magnitude of production and the probability of occurrence of system states. Productivity improvements are quantified and the productivity equivalency of reserve capacity to buffers is demonstrated.