Abstract
Conveyors are used to transport or deliver material and also to store it, and the conveyor-serviced production systems (CSPSystems) generally consists of multiple generalized conveyor-serviced production stations (generalized CSPSs) (Matsui, 1993). This paper studies an ordered-entry array of unit stations, generalized CSPSs, called a simple flexible assembly system (simple FAS). In this station-centered approach, the main concern is a coordination problem or system balancing between generalized CSPs, and this design problem has not yet been discussed anywhere. From the view of performance evaluation, we first found that allowing for only an overflow from the last station is sufficient to minimize the total expected cost of simple FAS, and there is a limit point to decrease the overflow rate by increasing a coefficient of overflows. Also, the arrangement of heterogeneous servers gave a counter example that the best server's arrangement under the case of in-process inventory is established by arranging the ascending order of processing rates to decrease both the overflow rate and the total expected cost. Second, we propose a simple 2-stage design method for simple FAS, and discuss an optimal design procedure using the complex-type method or genetic algorithms. This basic idea (Matsui, 1994) originates in dividing some design variables into input/output variables like cycle time and buffer variables like look-ahead times and reserve capacities. In this method, the first stage is to set the parameters, the cycle time and the number of stations. The second stage is to design the buffers, the look-ahead times and the reserve capacities under the given traffic. Finally, a design example is given and discussed.
