Research On U-shaped Assembly Line Balancing And Simulation

With the implementation of lean production, more and more assembly lines are designed with a U-shaped line layout. Compared to traditional straight line layout, the U-shaped layout is not only able to achieve a better line balancing, but also the layout of tight space, shortening of operators’walking path and reduction of material handling waste. Due to U-shaped line operators implementing the rotation system, with multi-skilled, and in close contact, it makes U-shaped line more flexible in operators assignment, product switching and cycle time adjustment, more able to respond quickly to changes in external demand. Research on the realities combination of U-shaped line balancing theory and U-shaped layout will be conductive to the implementation of U-shaped line in manufacturing enterprise. Based on the actual operation of assembly line, it researched on the practical application of U-shaped assembly line balancing problem in the paper. For U-line balancing problem with worker’s operating time stochastic distribution and in dependent of worker’s walking time, the method of using genetic algorithm combined with simulation modeling and analysis was proposed. Given cycle time and workstations completion rate the method of optimization via simulation model was presented to minimize the number of workstations. And the current workstations completion rate had achieved the designed target to solve the problems of practical application.Due to the actual complexity of the research problems, the basis theory of assembly line balancing was firstly summarized. U-shaped assembly line layout was introduced from the traditional straight assembly line layout. The description of traditional straight assembly line balancing problem was followed by U-shaped assembly line balancing problem, U-shaped assembly line balancing problem with operating time stochastic distribution and stochastic U-shaped assembly line balancing problem with considering worker’s walking path. Accordingly, the corresponding mathematical programming models were established. Operating time stochastic distribution of U-shaped assembly line balancing problem was solved by designing genetic optimization algorithm based on the feasible operating elements sequence encoding as the same summary method analysis solving straight assembly line balancing problem.For U-line balancing problem with worker’s operating time stochastic distribution and worker’s walking time, due to the limitation of the traditional method for solving mathematical programming models and the complexity of genetic algorithm for encoding and decoding process on the complex issues, the method of using genetic algorithm combined with simulation modeling and analysis was introduced. The simulation model of U-shaped line layout with considering worker’s walking path was modeled based on the output of GA for optimal operating sequence of elements. It simulated the stochastic distribution of worker’s operating time and the layout of workers’walking pathes.The content of this research meets the actual needs of manufacture enterprises. In order to make use of it more convenient and better for enterprise management personals, the system of U-shaped line balancing and simulating was designed. The principle of the system consists of the two main modules with each other:the optimization module of genetic algorithm and the simulation module of U-shaped line layout. The system platform was designed on discrete-event simulation software eM-Plant with modeling method of object-oriented. The designing of GA was coded by SimTalk language embedded in eM-Plant as the same with C++. The modeling of U-shaped line layout with workers’walking path was established by eM-Plant simulation modeling tools to counting and analyzing simulation data. Finally, a numerical example is developed to test and verify the feasible and efficient of the designed system.