Ergonomic mixed model U-type assembly line balancing

In this study, the Ergonomic Mixed Model U-Type Assembly Line Balancing (Ergo-KUMHD) Problem is discussed. The aim of the study is to both assign the workload to the operators more balanced in terms of ergonomics and to minimize the number of workstations opened. Thus, a more sustainable production flow will be achieved. In the study, a mixed integer linear programming model was developed for the solution of the problem and a solution was sought with the Genetic Algorithm (GA) approach for the problems that could not be solved in a reasonable time. Within the scope of ergonomic risk, the Quick Exposure Check (QEC) method was used in the model, and QEC scores were calculated as a result of observations made in a shock absorber factory in practice. The mathematical model was handled in a multi-purpose structure, and both the QEC score value of the station with the largest QEC score and the number of opened workstations were tried to be minimized. Since it is encountered in the application data in the model, an additional constraint structure for the work elements that should not be assigned to the same workstation is also used. The solution for the developed model was obtained using GUROBI. Since the weighted objective function structure is used, solutions for different weight values are analyzed. Even if the objective function weight for ergonomic risk is used at a smaller value, it has been observed that the model makes a balanced assignment to the stations. Even though the weight is chosen for this purpose, it is an important contribution of the study to obtain more ergonomically balanced workstations. GA model was developed for large problem data that could not be solved in a reasonable time, coded in Python Programming Language, and results were presented comparatively.