SOLVING THE COMBINED PART SEQUENCING AND TOOL REPLACEMENT-PROBLEM FOR AN AUTOMATED MACHINING CENTER - A TABU SEARCH APPROACH

This paper addresses a joint part sequencing and tool replacement problem on an automated machining center. The objective is to minimize the expected production cost subject to available spare tools. In the literature, it has been shown that the sequencing problems with sequence-dependent setups are equivalent to the ''travelling salesman problem'' (TSP) and thus are NP-complete. The problem under consideration is further complicated by the position-dependent cost components associated with tool replacement decisions. To provide an efficient planning tool for shop floor decision making, a tabu search approach is proposed. The application of the proposed approach is demonstrated using an example problem. Our computational experience shows that good solutions can be found within a relatively short search time. The impact of tool spare level on the performance of the machining center is also examined. Finally, the effects of tabu-list size and path diversification are discussed.