Optimizing U-Shaped Production Line Balancing Problem with Exchangeable Task Locations and Walking Times

This present study proposes to solve the U-shaped production line balancing problem with two constraints. First, following the precedence relationships between any pair of tasks, the locations of tasks are exchangeable. Second, all tasks are designed to be performed in fixed locations. When two or more tasks are assigned to the same operator, the walking time between the locations has to be considered when estimating the cycle time. The proposed problem is first formulated using an integer programming formulation, which is then solved by commercial software, LINGO, to minimize the cycle time and performance of the U-shaped production line. The empirical results show that U-shaped production lines outperform traditional straight production lines. In addition, the U-shaped production line balancing problem with consideration of walking time provides an opportunity to further reduce cycle time.