An approach to the hybrid organization of the shop layout

Abstract

While the benefits of organizing machines in form of manufacturing cells are highlypraised, certain industrials do not want a comprehensive transformation due to the possiblechanges that may occur, for example, in the parts' demands or routings. A hybrid manufacturingsystem that associates functional departments and machine cells may then appear much moreattractive given that it would takes advantages of both. Nevertheless, the design of such systemsis a much less researched issue compared to the effort spent to the efficient design of eachmentioned organization separately. In this work, we suggest an approach that penalizes theallocation of parts that are less stable to manufacturing cells, and highly stable to functionaldepartments. The abstract concept of part stability is associated with two part characteristics:routing similarity and demand variability. In order to determine the similarities between parts,sequence based similarity principles and alternative process routings are consideredsimultaneously. Meanwhile, demand variability is assumed to be related with the coefficient ofvariation. While such a discrimination of parts between manufacturing cells and functionaldepartments is desired, the flow of materials in the planned cells should also be appropriate.Suitable machine investment is another issue to consider. Hence, the hybrid manufacturingsystem design problem is formulated as a constrained multiobjective optimization problem.Evolutionary algorithms present important features for the solution of this type of problems.Among them, a very efficient algorithm which incorporates pareto dominance and elitism,namely SPEA2, is adapted. Both the proposed optimization model and the solution method areillustrated with an artificially generated example.Anahtar Sözcükler : Melez Üretim Sistemleri; Üretim Hücreleri; Fonksiyonel Yerlesim; ÇokAmaçlı Optimizasyon; Bulanık Kümeler; Evrimsel Programlama

While the benefits of organizing machines in form of manufacturing cells are highlypraised, certain industrials do not want a comprehensive transformation due to the possiblechanges that may occur, for example, in the parts? demands or routings. A hybrid manufacturingsystem that associates functional departments and machine cells may then appear much moreattractive given that it would takes advantages of both. Nevertheless, the design of such systemsis a much less researched issue compared to the effort spent to the efficient design of eachmentioned organization separately. In this work, we suggest an approach that penalizes theallocation of parts that are less stable to manufacturing cells, and highly stable to functionaldepartments. The abstract concept of part stability is associated with two part characteristics:routing similarity and demand variability. In order to determine the similarities between parts,sequence based similarity principles and alternative process routings are consideredsimultaneously. Meanwhile, demand variability is assumed to be related with the coefficient ofvariation. While such a discrimination of parts between manufacturing cells and functionaldepartments is desired, the flow of materials in the planned cells should also be appropriate.Suitable machine investment is another issue to consider. Hence, the hybrid manufacturingsystem design problem is formulated as a constrained multiobjective optimization problem.Evolutionary algorithms present important features for the solution of this type of problems.Among them, a very efficient algorithm, which incorporates pareto dominance and elitism,namely SPEA2, is adapted. Both the proposed optimization model and the solution method areillustrated with an artificially generated example.Keywords : Hybrid Manufacturing Systems; Manufacturing Cells; Functional Layout;Multiobjective Optimization; Fuzzy Sets; Evolutionary Programming