Scheduling for two stages with a single machine and a job shop

초록

This study considers a scheduling problem for two consecutive stages in sheet metal production. The first stage has a single part-cutting machine that cuts metal sheets on which the shapes of several types of parts are engraved. The second stage is a machining center in which four machine tools (punching, drilling, bending, and assembling) are organized in the form of a job shop. In the second stage, the parts that were cut in the first stage are bundled into a job according to the bill of materials, and they are processed in the required machining sequence. One of the main characteristics of this problem is that the parts for a job can be split into multiple metal sheets, and the job for the second stage can be continued when the cutting of all the necessary parts is completed in the first stage. The objective of the considered scheduling problem is to minimize the total weighted tardiness. For the problem, we propose a mathematical formulation and a simulated annealing-based two-phase algorithm. Computational experiments were conducted to evaluate the performance of the proposed algorithms. The results showed the excellent performance of the proposed algorithm. This study is expected to be applicable to other manufacturing industries with complex problems involving a single machine and job shop, as well as sheet metal production.

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