Study On The Scheduling And Optimization On The Manufactyring And Assembly In Hybrid Flow-shop For One-of-a-kind Production

Since 21 century, the development trend of product demand is transferring from standardization and batch production to diversification and individuation, meanwhile the manufacturing type is also evolving from volume-production to one-of-a-kind production (OKP). Contemporary die and mould manufacturing enterprise is the typical OKP enterprise that produce facilities as moulds professionally, which possesses characteristics of general OKP enterprise and some other mould manufacturing cycle long and the high work-in-process inventory features because of the particularity of mould production process. the production tasks will be unable to complete on time, Tardiness is serious, This not only allows businesses to have higher production costs, but also affect the enterprise prestige, influence customer satisfaction, severely restricted the development of mould enterprises in our country and international competitiveness. In order to be able to timely respond to customer diversification demand, at the same time, not to increase the inventory of the enterprise, reduce the wip inventory, therefore, based on the degree of order delivery on time and product assembly parts at the same time degree as the optimization goal when considering manufacturing and assembly integrated optimization scheduling problem.This research deals with a scheduling problem of one-of-a-kind products. Two main challenges which complicate the scheduling problem are identified. Firstly, if a product is assembled with multiple components, the final assembly can only start after all component parts of the product are completed; secondly, highly customized production may result in long production lifecycle and high work-in-process inventory. The problem can be divided into two phases. The first phase is a hybrid flow shop, and the second phase is one stage assembly. In the first phase, all operations are well ordered and flow across a set of production stages sequentially each of which comprises a set of parallel machines. After all components are finished, all component parts of the same product will be assembled on an assembly site in the second phase. The model is developed to optimize the overall earliness/tardiness and production simultaneity in the first phase to lower down the work-in-process inventory cost.1. Introduce hybrid flow shop scheduling problem, mold processing and assembling scheduling optimization model is set up under the sheet production scheduling problem.2. In view of the scheduling model is established, the coding method based on machine, using non dominated sorting algorithms with elite strategy for problem solving, heuristic algorithm is designed to produce part of the initial population, Expounds encoding and decoding way, way, crossover and mutation operators of the algorithm to solve the existing problems are analyzed and the corresponding improvement, through the elite strategy of the improved dominant genetic algorithm to solve the double objective optimization solution of the scheduling example, shows the algorithm of the improved effect;3. Finally, through the contrast test with GA algorithm and PSO algorithm, the test results show that the improved the NSGA-â…¡ algorithm has better optimization performance.