A Non-dominated Sorting Approach to Bi-objective Optimisation of Mixed-Model Two-Sided Assembly Lines

Assembly lines are of widely utilized mass production techniques emerged after the industrial revolution started in 18th century in England. Ever since, the changes in the global market and increasing interest in customized products forced companies to change their production systems in such a way that customer demands can be met in a more flexible environment. Assembly line balancing problem is an NP-hard class of combinatorial optimization problem for which exact solution techniques fail to solve large-scaled instances. This paper addresses to the problem of balancing mixed-model two-sided assembly lines, on which large-sized products (such as automobiles, trucks and buses) are assembled in an intermixed-sequence, with the aim of minimising two conflicting objectives (cycle time and number of workstations). A new ant colony optimization approach, called non-dominated sorting ant colony optimization (NSACO shortly), is proposed. Thus, the NSACO algorithm is used for the first time to solve an assembly line balancing problem. NSACO is described in details and a numerical example is solved to demonstrate its solution building mechanism. The results indicate that NSACO has a promising performance.