The equivalence of duplicate automated serial workstations and two-workstation tandem systems and its use in serial production line analysis

In automated serial production systems it is sometimes necessary to maintain two identical workstations in series, with jobs receiving processing on only one of these two workstations. This is required because a single workstation may not have sufficient capacity to support the target throughput rate and due to cost, space, and sequencing reasons, the workstations are not arranged in parallel. We show how these duplicate automated serial workstations can be approximated by a two-workstation tandem system with zero buffer. The parameters of the tandem system are simple functions of the duplicate workstation parameters. In isolation we show that the tandem system is equivalent to the duplicate workstation system. When part of larger serial production system, the equivalence no longer holds; however, simulation testing shows that a two-workstation tandem system approximation to the duplicate workstation system is very accurate. This extends the analysis capabilities of analytical tools and simulations that are tailored for serial production systems, but do not explicitly model duplicate workstations.