A queueing network model of a single-operator manufacturing workcell with machine/operator interference

The authors present an analytical approach to evaluate the performance of a manufacturing workcell tended by a single operator when operator-induced machine interference occurs. Each part must be processed at every workstation in the workcell. The fact that one or more machines can request an operator service while the operator is busy at another machine induces machine interference. If the reduction of the workcell’s capacity due to this interference becomes too great, then the customer demand may not be satisfied. The present approach determines quickly whether the workcell can meet a required demand under its current configuration and operating parameters. The authors do this by modeling the workcell as two interacting queuing networks: an open part/machine network, and a closed machine/operator network. In the open network, parts arrive in batches of a fixed size for each part type, but with exponentially distributed interarrival times between parts. In both networks, service times follow general distributions that are characterized by their first two moments.