The design of a cellular manufacturing system requires that a part population, at least minimally described by its use of process technology (part/machine incidence matrix), be partitioned into part families and that the associated plant equipment be partitioned into machine cells. At the highest level, the objective is to form a set of completely autonomous units such that inter-cell movement of parts is minimized. We present an integer program that is solved using a genetic algorithm (GA) to assist in the design of cellular manufacturing systems. The formulation uses a unique representation scheme for individuals (part/machine partitions) that reduces the size of the cell formation problem and increases the scale of problems that can be solved. This approach offers improved design flexibility by allowing a variety of evaluation functions to be employed and by incorporating design constraints during cell formation. The effectiveness of the GA approach is demonstrated on several problems from the literature.

Layout and packing are NP-hard geometric optimization problems of practical importance for which finding a globally optimal solution is intractable if P!=NP. Such problems appear in industries such as aerospace, ship building, apparel and shoe manufacturing, furniture production, and steel construction. At their core, layout and packing problems have the common geometric feasibility problem of containment: find a way of placing a set of items into a container. In this thesis, we focus on containment and its applications to layout and packing problems. We demonstrate that, although containment is NP-hard, it is fruitful to: 1) develop algorithms for containment, as opposed to heuristics, 2) design containment algorithms so that they say "no" almost as fast as they say "yes", 3) use geometric techniques, not just mathematical programming techniques, and 4) maximize the number of items for which the algorithms are practical. Our approach to containment is based on a new restrict/evaluate...

Many companies have the aim of reducing part variety as it confers on it a range of significant benefits. Achieving this requires a retrieval system that is effective, that designers will use and that is cost effective to implement and maintain. Coding and classification/Group Technology(GT) codes are widely used in systems for retrieval of existing parts but involve expensive and time consuming manual coding. A system called Camac has been developed which uses a novel approach of automated coding of 2D engineering drawing to deliver a cost effective solution with the added benefit that searching is based on a CAD sketch of the part and not text descriptors. Testing has already shown that the performance of Camac to be excellent but that it may be affected by the detail and quality of the seed sketch. Testing is describe which investigates the impact of sketch detail and quality as well as database size. It is concluded that an acceptable performance with poor quality sketches should be attainable with databases in excess of 20000 items and that for good quality sketches databases of significantly greater size will not be a problem. Key Words: design retrieval, coding & classification, Group Technology (GT) 1.

Flexible flow shops are becoming increasingly common in industry practice because of higher workloads imposed by jobs on one or more stages, thus requiring two or more units of the same machine type. We present a methodology for solving this important problem, namely group scheduling, within the context of cellular manufacturing systems in order to minimize the total completion time of all groups of jobs considered in the planning horizon. Two different setup options, namely ############ and ###############, are investigated for jobs within the same group. A combined heuristic solution algorithm, comprised of single- and multiple-pass heuristics, is used for solving the problem. An example problem, consisting of three different problem instances of the same structure, is used to not only demonstrate the applicability of the solution algorithm, but also to identify the setup to ####### job run time ratios that should ###############prevail across all stages represented by two or more identical units in order to select ############### over ############ or vice versa. Keywords Group Scheduling; Flexible Flow Shops 1.

Cellular manufacturing is a promising approach for grouping eciency in manufacturing systems. Although this problem has been extensively studied in the literature, very few authors have proposed exact methods. The basic cellular manufacturing problem consists in dening cells which lead to the minimum number of bottleneck elements. In this paper, we consider a new formulation of the cellular manufacturing problem where each variable corresponds to a potential cell. In order to deal with the large number of variables, we propose a solution scheme based on column generation techniques. We discuss its eciency and compare it with other exact methods proposed in the literature. Keywords: Group technology, cell formation, column generation, bottleneck parts. Resume La formation de cellules de production est une approche prometteuse pour eectuer des groupements ecaces dans les systemes manufacturiers. Bien que ce probleme ait ete beaucoup etudie dans la litterature, peu...

this paper is the development of a hierarchical cell loading approach to solve the production planning problem in CM systems

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