برون سپاری و برنامه ریزی تولید برای روند دو مرحله ای فروشگاه

In this paper we study the production scheduling problem for a two-stage flow shop in which there are options of outsourcing some operations to subcontractors. The basic objective is to look for a production schedule that can optimally utilize the resources of both the in-house production and outsourcing so that the makespan is minimized. The logistics issue between the subcontractor and the in-house shop further complicates the problem. We present models for different situations of outsourcing. For each model, we develop optimization algorithms and conduct computational experiments to study the managerial insights for the models and the algorithms.

With the economy globalization and the development of information technology, outsourcing is playing a more and more important role in manufacturing industries. Outsourcing can help a manufacturer in different ways. By fully outsourcing some non-critical operations to subcontractors, a company can focus more on its core business. This has become a popular business practice for many high-tech manufacturers. Outsourcing may also be taken for the purpose of tax benefit. For example, to avoid the restriction of the import quota imposed on the textiles made in China, companies in Hong Kong can use suppliers in nearby cities in China to do a portion of the work as preprocessing, then transport the unfinished products to Hong Kong where they would undergo additional processing to become Hong Kong-made products. In other situations, outsourcing can be used as a secondary supplying source in addition to the in-house production. In such a way, a manufacturer can effectively handle demand fluctuations without the need of maintaining a high production or inventory capacity. While a manufacturer can benefit from outsourcing, the potential maximum benefit cannot be achieved unless there is an efficient and effective production plan and schedule that can cope with the complexity of outsourcing. The problem is challenging in that we have to take care of the scheduling for both the in-house production and the subcontractor's production, as well as their coordination. The purpose of this paper is to study the production scheduling problems in a two-stage flow shop with the options of outsourcing. In the base line of the problem, the in-house production is the sole supplying source. There are a set of jobs to be processed, and each job has to go through two sequential operations by two different machines. The problem is to determine a sequence for processing the jobs on the two machines so that the makespan, i.e., the completion time of the last job on the stage-two machine, is minimized. This is one of the classic scheduling problems, and can be solved by the well-known Johnson's rule.

In this paper, we have studied different scenarios for two-stage flow shop scheduling problems with options of outsourcing. In practice, outsourcing may still be in other forms, for example, partial outsourcing for one stage only (Qi, 2009). Thus it would be interesting as future work to study a more general model that allows for outsourcing at any stage with multiple subcontractors. Our focus has been on the problems at the operational level. Given a specific configuration of outsourcing, we have developed optimization algorithms to find the best schedule, and conducted computational experiments to study managerial insights for the models and the algorithms. Another strategic-level question would be the choice of a particular form of outsourcing by comparing different options of outsourcing. Such decisions usually involve other more complicated issues that are not included in the current models, for example, considerations on resource constraints, technique availability, environmental impact, and even politics. Nevertheless, our operational level results would provide important information for the strategic decisions.