Input sequencing and scheduling for a reconfigurable manufacturing system with a limited number of fixtures

Abstract

We consider the input sequencing and scheduling problems in a reconfigurable manufacturing system, a state-of-the-art manufacturing system designed at the outset for rapid changes in its hardware and software components. Due to the inherent operation and routing flexibilities of the system, each part is processed according to a multiple process plan, i.e., each part can be processed through alternative operations, each of which can be processed on alternative machines. The main decisions are: (a) the sequence of parts to be released into the system; (b) the selection of operation/machine pair; and (c) the sequence of the parts assigned to each machine within the system. In particular, we consider the practical constraint that the number of fixtures is limited and hence a part can be released into the system only when the fixture required for the part is available. To solve the integrated input sequencing and scheduling problems, we suggest a practical priority rule based approach in which the three decisions are done using a combination of dispatching rules, i.e., those for input sequencing, operation/machine selection, and part sequencing. To show the performances of various rule combinations, simulation experiments were done on the data derived from a real system, and the test results are reported.