Operations scheduling in flexible manufacturing systems for maximum throughput

Abstract

Planning for the schedule of operations in flexible manufacturing systems (FMS) must take into account both the multiprocessing environment and the dynamically changing states. In this thesis, a procedure for scheduling the operations in FMS is developed. The objective is to maximize the throughput of the system by minimizing the production cycle time at machining (fabrication) stage where both the machining time and the material handling time among machines are heavily considered. The problem is investigated in a two-step procedure. In the first step, machine loading schedules are found. Once machine loading schedules are set up, a production route for each part which implies a sequence of machines corresponding to the given sequence of operations for the part is determined. In other words, all the operations required for each part are assigned to each machine. In the second step, the operations sequencing is formulated to minimize the repeating production cycle time. Such a sequencing means the best possible sequence of operations within each machine. Both the steps employ efficient heuristic algorithms which are illustrated with numerical examples.