Integrated Optimization Of Lean Inbound Logistics

The logistics of manufactories can be mainly classified as inbound logistics, in-plant logistics, outbound logistics and return logistics. Inbound logistics is the important linkage between the first-tier suppliers and manufactory, as one of the fundamental value-adding activities of manufactory. Manufacturer's inbound logistic system is much more complex than outbound one, especially to assembly plant, such as Vehicle Manufactures, but less attention has been paid.Inbound logistics system is the significant support of manufactory's production system. While worldwide manufactories are applying Lean production system, Lean should also be extended to the Inbound Logistics system in order to support Lean production. The assembling line produces products under Just-In-Time principle In Lean production, with the requirement to inbound logistics that all the raw material and parts should be supplied to the line just-in-time when they are needed. In Lean inbound logistics, the parts are moved efficiently in small lot-size and high frequency, so as to eliminate the wastes caused by inventory.In the dissertation, under Lean principle, the integrated optimization of assembling manufactory's inbound logistics is researched, with main attention to tactical decision level. During the research, all the related activities and costs happening in the supply period will be integrated optimized, such as production, transportation, inventory holding and so on, which are paid by suppliers, manufactory or logistics provider.At first, based on the summary of literatures, the goal and content of inbound logistics management are described and a concept model of the system is given. We propose the basic architecture of manufactory's inbound logistics, the principle and operational mechanism of lean inbound logistics and the ABC Classification method of parts' supply, which is used to solve an important tactical decision: whether the part is supplied by direct method or indirect method.Then, to class A parts, the integrated optimization models of inbound logistics by direct supply method is studied. Considering suppliers under various production rules, such as synchronous production, batch production and mixed line production, different models under different production rules of suppliers are constructed and solved. Then the operational constraints during transportation and warehousing are involved and give out the operational solution. According to single part optimization, the multiple parts problem is solved, with case study of an auto parts supplier in Shanghai.To class B/C parts, the integrated optimization models of inbound logistics by indirect supply method is studied, which means the parts are supplied through external warehouses. We work on three kinds of optimal problems under different freight consolidation configurations: without consolidation neither in collection or delivery transportation, with consolidation in delivery but not in collection, and with consolidation both in delivery and collection. To delivery consolidation, we try to treat the problem as Joint Replenishment Problem. To collection consolidation by milk-run routes, we treat it as Inventory Routing Problem. The integrated optimal models are analyzed and constructed, which will not be solved by exact algorithm because they are both kind of typically NP Hard combination optimization problem. We design and develop several optimal algorithms to search for the satisfying solutions: A heuristic based on BFD, a grouping genetic algorithm with bin-based representation, a heuristic based on C-W saving with updating, and a mix grouping genetic algorithm. Numerical results of problems with 40 kinds of parts from real case are solved and analyzed, which can verify the effectivity of the algorithms.The decision optimization cannot be implemented successfully in real supply chain without the suitable operational business mode of inbound logistics, so another important decision, the choice of inbound logistic mode is discussed. The traditional unintegrated inbound logistics mode and the integrated LLP mode are both analyzed and compared with computer simulating results.In conclusion, further research directions are briefly discussed.