The Assembly Line Simulator Project: modeling U-shaped, un-paced, mixed model assembly lines

To evaluate performances of U-shaped un-paced mixed model assembly line may be complicated. This complication is a result of blockage and starvation caused by the arrival of different models to the line, having different assembly time requirements at each station. Considering the throughput as the main operational design objective, the effects of these phenomena on line throughput are very difficult to evaluate. Unfortunately, its evaluation is fundamental in almost all procedures and algorithms developed to solve U-MALBP (U-shaped Mixed-model Assembly Line Balancing Problem), since the estimation of objective functions that includes performance indicators is often required. The only practical method to accurately evaluate throughput is a simulation study, which is very time consuming and hard to perform. For this reason, instead, various performance measures, not simulation based, have been presented in literature in order to evaluate and compare design alternatives. Unfortunately, these performance measures are often poorly correlated to the real value of the throughput when the complexity of the line increases. The aim of the Assembly Line Simulator Project is to overcome the limit of using performance measures instead of simulated throughput, by developing a parametric simulator for mixed model lines that can quickly simulate different line configurations and can be used iteratively in algorithms and procedures. In the paper, the last version of the simulator, designed for U-shaped lines, is presented and tested.