A Bi-objective Sequencing Decision-making Model Of Mixed-model Assembly Line

Mixed-model assembly line with multi-product and small batch is of operation characteristics as below: small quantities, complex manufacturing process, high conversion frequency, high-flexibility of the production plan, etc. Sequencing model is the one of most important decision of production plan and control for this kind of assembly line. By existed method of sequencing, major customer demand are given priority to sequencing, then other customs’ orders are inserted randomly if there is still spare capacity. This method is conclude the rule of material balance, thereby causes many problems: hardly to implement production plan, inventory excess coexisted with shortage, high assembly setup cost, unguaranteed delivery date and so on.This dissertation firstly studies domestic and foreign similar documents of mix-model assembly line sequencing problem, analyze the impact to production organization. Then according to customs’ importance degree and lead time divides the products into four categories: core strategic products I, customer-oriented products II, time-oriented products III, is ordinary products IV. And then two principles are proposed for every category of product. By using Minimal Production Set, goal chasing algorithm and product family, two-objective with minimum variations of part usage rate and minimum assembly switch cost sequencing model is given. Finally, the optimal solution set of every categories in a MPS are solved with GA, so that decision-making method is clear offered on mixed-model assembly line sequencing problem when with different structure characteristics of demand.Get optimal or near-optimal solutions of whether classify the production category by GA, and select the most optimal sequencing plan. The results show that two-objectives sequencing model above outperforms good shown as four parameters with work-in-process inventory, rate of material balance, assembly setup cost, lead time, etc.Application example shows that, production classification method is beneficial to balance the contradiction between customer demand and enterprise capacity. On the one hand, by sequencing reasonably considering product category and quantity, it can eliminate logistics bottleneck of workstations, ensure material consumption smoothly and material supply on time, comprehensively balance product, time, quality and equipment load, etc. On the other hand, it also can reduce switch time even production cost.