A METHODOLOGY FOR SIMULTANEOUSLY DEALING WITH MACHINE DUPLICATION ANDPART SUBCONTRACTING IN CELLULAR MANUFACTURING SYSTEMS

In this article, we present a model and a solution algorithm for deali ng simultaneously with duplicating bottleneck machines and subcontract ing bottleneck parts under budgetary restrictions in CM systems. Becau se the problem is proven NP-hard in the strong sense, a higher-level h euristic algorithm based upon a concept known as tabu search is presen ted. The functionality of the algorithm is demonstrated by solving an example (small) problem. Further, the small problem as well as a varia nt of the small problem are solved for the optimal solution, and the s olutions obtained at four different budgetary levels are shown to matc h with those obtained with the heuristic algorithm. The applicability of the algorithm for problems encountered in industry practice to crea te either completely disaggregated or nearly completely disaggregated manufacturing cells is demonstrated by solving a fairly large problem that has appeared in the published literature. When parts manufacturin g companies are subject to budgetary restrictions, the results obtaine d show that the proposed approach can be used to determine which of th e following three actions should be undertaken for each bottleneck par t. That is should, the bottleneck part be left as in the initial solut ion, all the bottleneck machines connected to it be duplicated, or the part be subcontracted? Copyright (C) 1997 Elsevier Science Ltd