Multi-Objective Optimization for Multi-Line and U-Shape Layout of Sewing Assembly Line in Apparel Industry

The design of assembly line layout is one of the most important influential factors for the company's performance. The inappropriate arrangement of the order of workstations in the assembly line could cause the excessive movement of the material. In order to increase productivity and reduce production cost, a multi-objective optimization model with minimum the transfer distance of semi-finished products and the total area of assembly line was established in this paper. The Non-dominated Sorting Genetic Algorithm-II was applied to obtain the results of this model. The coding method, genetic operation and fitness function for three different kinds of sewing assembly line layouts (multi-line, U-shape two-line and U-shape three-line) were studied, while the workstations were organized in three ways: the order of processes, the type of machines, and the components of garment. The efficiency of the model was verified by the practice of sewing assembly lines for men's shirt. The layout schemes are compared with other algorithms. The results illustrated that NSGA-II algorithm is an effective tool to solve the sewing assembly line layout problem. The transfer distances of semi-finished products in the multi-line and U-shape (three-line) layouts arranged by garment components workstation layout were short. The multi-line layout arranged by the type of machines workstation layout occupied the smallest area. The model is suitable for solving the layout problem of the garment sewing workshop in practice, shortening the production cycle, and reducing the production cost. A variety of assembly line layout schemes are provided for apparel manufacturers in this paper. Apparel manufacturers can select the appropriate assembly line layout based on the actual conditions of the workshop and product.