Ga-based integrated procedure of line balancing and job sequencing for mixed-model assembly line: A comparison of ushape and straight line

Mixed-model assembly line is a type of a production line where a variety of product models with certain level of similarity in operational characteristics are assembled. Due to this variety, especially, work load variance cause several inconvenient phenomena such as low efficiency, line stops. To cope with these problems, hierarchical design procedure for line balancing and job sequencing is proposed which is structured in terms of amelioration procedure. On our Genetic Algorithm, a new encoding procedure entitled Priority-based Multi-Chromosome (PMC) is proposed, of which feature is a multi-functional chromosome and provides efficient representation of task assignment to workstations and job ordering. From lean production point of view, U-shape assembly line system has been recognized to offer several benefits over the traditional straight line system. To assure effectiveness of proposed procedure, both straight and U-shape assembly lines are examined under three major performance criteria, i.e. number of workstations (or line efficiency) as static criterion, variance of workload and distance between average and actual workload on the assembly line as dynamic criterion. The results of simulation experiments suggest that proposed procedure is effective management tool of mixed-model assembly line system.