| Today,customer demands are becoming increasingly diversified.The characteristics of small batch and more various orders are prevalent in the enterprise,and have been the production challenges that each company faces.The companies gradually turn to make to order organizing production In order to meet customer needs.Producing a variety of types of products in an assembly line can be needed and companies are increasingly requiring the flexibility of production.The two-stage assembly flow shop environment is very common in production.Firstly,parts are processed in the first stage,and then those parts are used to assemble the final product on the assembly line after the completion of the processing on the basis of BOM.Therefore,the coordination between the two stages is particularly important.Especially When there is a bottleneck in two-stage production,bottleneck processes at different locations restrict the efficiency of the whole production system.In the traditional scheduling,production scheduling is performed separately for each stage,resulting in mismatch between supply and demand during the two stages,an increase of the delivery time and makespan,meanwhile reduce customer satisfaction.Therefore in order to improve the company's production efficiency and ability to quickly respond to the market,it is very important to optimize the scheduling of the two-stage assembly flow shop.This article begins with the theory and the research status at home and abroad is summarized.The problems in the production process between the parts processing line and the product assembly line with the bottleneck process were studied.The parts were directly distributed to the work station in the model,and setup time is considered related to the sequence.On this basis,in order to ensure the coordinated and efficient production between the two stages,an effective solution was proposed.This can minimize the makespan and total tardiness,and also can improve the efficiency of the entire production system and customer satisfaction.In the two stage assembly flow shop,in order to ensure the components that are produced in the component production stage can be accurately and timely supplied to the assembly line for assembly,and make the minimum completion period,make our products timely delivery to customers at the same time,the scheduling method in the two-stage assembly flow shop is studied.Firstly,the mathematical model of the two stage assemblyflow shop is established to analyze the impact of the bottleneck process on the whole production system when it is in the processing stage and assembly stage respectively.Then,In terms of problem solving,a heuristic search method with considering the bottleneck machine is proposed combine Johnson rule and neighborhood search,the effectiveness of the proposed method with single objective is proved by data experiments and compared with other heuristics such as SPT,LPT,EDD,NEH,and VNS.Finally,the migrating birds algorithm is proposed to solve the multi-objective problem.The solution transfer and preserve rules in the migratory bird algorithms are designed,and the strategy of selecting the leader bird is also designed.Three kinds of neighborhood search methods are used.Through small size examples and comparison with enumeration method,it is proved that the algorithm can find solutions on the frontier surface.Compared with the NSGAII algorithm through a large scale example,the effectiveness and validity of the algorithm is proved. |
