Reconfiguration of Machining Transfer Lines

International audienceIn this chapter, we introduce a new optimization problem that aims at minimizing the reconfiguration cost of a transfer line. A line has to be reconfigured if a new product must be produced by an existing line or any changes in product characteristics occur. In such cases, new operations have to be integrated on existing equipment while some previously assigned operations are deleted. Since transfer lines consist of a sequence of unit head machines, their reconfiguration is not an easy issue because of numerous constraints on compatibility between old and new operations to be taken into account. Therefore, a compromise between introducing new equipment and reusing old one should be found. In this chapter, a Mixed Integer Program is proposed for solving this problem with objective to minimize the cost of the final line configuration. An illustrative example is presented

A heuristic multi-start decomposition approach for optimal design of serial machining lines

We study an optimal design problem for serial machining lines. Such lines consist of a sequence of stations. At every station, the operations to manufacture a product are grouped into blocks. The operations within each block are performed simultaneously by the same spindle head and the blocks of the same station are executed sequentially. The inclusion and exclusion constraints for combining operations into blocks and stations as well as the precedence constraints on the set of operations are given. The problem is to group the operations into blocks and stations minimizing the total line cost. A feasible solution must respect the given cycle time and all given constraints. In this paper, a heuristic multi-start decomposition approach is proposed. It utilizes a decomposition of the initial problem into several sub-problems on the basis of a heuristic solution. Then each obtained sub-problem is solved by an exact algorithm. This procedure is repeated many times, each time it starts with a new heuristic solution. Computational tests show that the proposed approach outperforms simple heuristic algorithms for large-scale problems.

DECISION MAKING AND SUPPORT TOOLS FOR DESIGN OF MACHINING SYSTEMS

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