A thesis submitted in partial fulfillment of the requirements for the degree of Master of Engineering, School of Engineering and Technology

Thesis (M.Eng.) - Asian Institute of Technology, 1992

In this study, a batching approach to the selection of part types for simultaneous processing by an FMS is presented. The objective is to maximize the number of part types in a batch. Constraints on tool magazine capacity and tool type availability are considered. Two alternative strategies of assigning weights in the objective function of the part type selection model are explored to direct the search to a different set of part types. An existing procedure to dete1mine the mix ratios of the selected part types is used so as to balance the aggregate machine workloads. The mathematical programming formulation is aggregate in the sense that it does not take into account such FMS factors as limited buffer space, travel times of WIP, and dispatching rules. In the current study, these model aggregations have been accounted for in a simulation study conducted on a realistic flexible flow system (FFS). The simulated settings have been constructed · to evaluate the performance of the batching approach and to investigate the sensitivity of total makespan and machine utilizations to these aggregations. For the situation examined, the simulation results indicate that the makespan and machine utilizations are a strong function of the speed of the conveyor used to transport parts between processing stations. Results also indicate that the number of buffer spaces have little or no effect on the system performance because of the conveyor which itself acts as a larger buffer. Number of pallets has been shown to influence system performance only at lower conveyor speeds.