A genetic algorithm application for aircraft component assembly line balancing and labor assignment problem in a defense industry company

The assembly line which known as a production structure composing of workstations with a certain production capacity, where the operations required for the production of final or intermediate products are carried out in a certain order. Assembly Line Balancing is the approach of operation assignment to different workstations, taking into account other predetermined constraints such as resource, capacity, workforce, and placement, in a way to ensure the priority relationship between operations that should be performed in production. In this study, a single model aircraft component assembly line in a defense industry company is discussed. Operation times were measured by time study studies and were considered deterministic within the scope of the application. In this study, the precedence relationship between the operastions are determined with using work study techniques. Line balancing is very important in terms of production efficiency, especially in the automotive, white goods and electronics sectors. Unlike assembly lines in other industries, the aircraft component assembly line is more labor intensive. It is critical to assign workforce in a way that increases productivity. Different tools / equipments are required for each operation. With this constraint, it is known that not every assembly operation can be performed at every assembly station. In the single-model aircraft component assembly line, which is the subject of the study, each operation and the potential assembly stations where each operation can be carried out is shown as a constraint in this problem type. The manpower and budget to be allocated by the company for the aircraft component assembly line are determined in advance and have been reflected in the application as a constraint. Considering that the operation times vary depending on the different skill levels of the each operator performing the operation, a new mathematical model has been formulated for budget constrained assembly line cycle time minimization for the problem of assembly line balancing and manpower assignment. Considering the determined constraints and assumptions, this mathematical model aiming at cycle time minimization was resolved in the GAMS program by modeling it with small-sized problem data, and the best solution was obtained, so as to provide priority relationship between tasks. Real life problem data with big-sized were modeled in Python 3.7.6 program with genetic algorithm to reached the feasible solution. In this way, it was determined which operation will be worked in which station and which operator will work in which operation in the aircraft component assembly line, for which the minimum cycle time is aimed. Keywords: Assembly line balancing, Mathematical model, Labor assignment, Genetic algorithm