Modelling and Simulation Study to Determine the Suitable Number of Direct Labours and Balance the Assembly Line

The case study company is the producer of an automotive exhaust pipe that currently faced challenges in high expenses and decreased customers demand. The purpose of this study was to improve production process by reducing the number of required direct labour and balancing the assembly line resulting in the improvement of direct labour cost and operator utilization. The final assembly line focused in the study was the assembly line which had overproduction. Therefore, it was selected for this study. This study focused on two major products, accounted for 90.78% of overall production capacity, which were HR1 and HR2. Simulation was applied to mimics the current process which had 7 operators by using Arena software package. There are 3 scenarios in the study after verification and validation the simulation model of the current process. Each simulation model has 5, 4, and 3 number of operators, respectively in order to compare the results. The current process and the 3 proposed scenarios aim to compare 3 Key Performance Indicators (KPIs), comprising 1) number of finished parts, 2) operator utilization and 3) direct labour cost. The scenario 2 using 4 operators inclined to give the best results among them. It met the average actual demand while satisfying the operator utilization and direct labour cost. The result of this scenario satisfied all 3 KPIs mentioned above: number of finished parts produced best fit the actual demand, reduced the direct labour costs by 42.86 percent, and increased the operator utilization by 19.39 percent.