Assembly line balancing is an important subject of many production systems whenever the line design is performed. The output rate of the line must deal with
the change in the demand of various products so as to satisfy the customers’expectation and the fluctuant market demands. However, assembly line balancing will affect the decisions on the capacity of a factory and the resource allocations, and then the output rate of the line is decided. In the traditional assembly line balancing problems, the assignment of tasks to an assembly line is in sequential way, and some different objectives are optimized under satisfying various constraints while performing a line balancing.
Assembly lines with multi-manned workstations, where workers simultaneously perform different tasks on the same workstation, are widely used in producing large-sized products such as the case of vehicle’s final assembly. Therefore, this research considers the simultaneous production for tasks. That is, workers simultaneously perform same or different tasks on the same product and
workstation in an assembly line. Whenever a simultaneous production is allowed for the entire tasks in an assembly line, the assembly line balancing problems become more complicated. In this paper, the mathematical optimization models for the assembly line balancing problems with multi-manned workstations are proposed under considering the simultaneous production, and the tasks assignments to a multi-manned workstation are performed in terms of the task
routes of individual part. That is, the partial tasks belonging to a part, which are assigned into a multi-manned workstation, are performed by one worker. In
Chapter 2, a statement of the problem we deal with is given, and some problems, such as the assignment of the common tasks, encountered in performing simultaneous tasks assignments are described. A coding system, Four-Position
Code (FPC), is also proposed to re-code the tasks to tackle above issue.
In this study, the single-model and mixed-model assembly line balancing problems are considered. Hence, the mathematical optimization models for the above-mentioned assembly line balancing problems with simultaneous production are proposed in Chapter 3 and Chapter 4, respectively. The objective functions of the proposed models are to minimize the number of workstations of the assembly line under the following constraints: assignment constraints, precedence constraints, cycle time constraints, and workstations constraints. And then, based on the optimal results, the number of workers is assigned to each workstation of the line, and the total idle rate of the line is also computed. In addition, the proposed models are further clarified by some illustrative examples, and simulation analyses for various cycle times and performance of the proposed model are also conducted.