Multi-Manned Assembly Line Synchronization with Compatible Mounting Positions

The assembly of large and complex products as cars typically involves a huge amount of production resources as workers, pieces of equipment and layout areas. Multi-manned workstations commonly characterize these assembly lines along with some additional features such as compatibility/incompatibility between the different mounting positions, equipment sharing and worker cooperation. The simultaneous management of all such aspects significantly increases the balancing problem complexity. This paper proposes a new mixed integer programming model for such multi-manned assembly line synchronization problem to simultaneously optimize the line efficiency, the line length and the workload smoothness. A customized procedure based on a simulated annealing algorithm is developed to effectively solve this problem. The aforementioned procedure is validated through an industrial case study of an Italian sports car manufacturer distinguished by 665 tasks and numerous synchronization constraints typical of real assembly lines