Analysis of the mixed model assembly line balancing deterministic and stochastic measurements in a tractor plant

Assembly lines are systems that allow the products with multiple components and, mass demands, to be manufactured together in sequential workstations. Assembly lines and design are among the main factors that increase the efficiency of production in factories in the white goods and electronics sectors, especially in the automotive sector. Numerous studies have been carried out using deterministic, stochastic heuristic and fuzzy methods related to the design and balancing problems of assembly lines. In this study, the distribution of work steps to the operators during the daily working period was carried out in a real assembly line of a tractor factory. Since the parts belonging to more than one type of tractor model are assembled in the factory assembly line, mixed model assembly lines are examined. The duration of the operations for the assembly was measured by time study studies. Accordingly, it was observed that the working times were random and dependent on the worker. In a parallel type assembly line, worker-dependent working times are also taken into account randomly. Line stoppages are experienced on the assembly line due to factors such as lack of training, the presence of complex jobs, and reduced motivation of work. Line stops cause deviations in the number of tractors that need to be produced daily, thus causing losses in the factory. In a mixed model assembly line where multiple work steps take place, there may be minor variations between operating times. Balancing analyzes were used on the assembly line to measure all losses. Within the scope of the study, considering the work step differences in tractor models, a priority diagram was obtained with the model-based unified priority diagram method. Stochastic assembly line balancing study was performed according to the stochastic working times on the line and the analysis results were compared with the deterministic results. In addition to the advantages of using stochastic working times, heuristic results have been obtained for the solution of the assembly line balancing problem with the java algorithm, which gives the minimum number of stations to be opened in the cycle time determined using the intuitive method Arcus (1966) proposed COMSOAL method. The number of stations to be opened according to the algorithm is determined at different cycle times. Thus, a line structure prepared for sudden plan changes at the factory was obtained. According to the station distribution obtained as a result of balancing and job assignment on the assembly line, efficiency analyzes are presented and the results are evaluated.