Performance evaluation of unbalanced serial production lines

Here an efficient approximation method is proposed to evaluate the throughput rate of unbalanced serial production lines. The approximation method analyses successive pairs of adjacent stations, and then the solution of a previous two-station system is used in the analysis of the next pair. A number of experiments were performed by simulation for the two-station system. Predictive models of the throughput and the coefficient of variation of interdeparture times for the two-station system have been derived from regression analysis. The line throughput rate of a larger system can be evaluated by repetitively applying these models. Numerical results show that the proposed method works very well even for long production lines. Based on these results, the problem of buffer capacity design is also discussed. Dynamic programming algorithms are proposed to determine the minimum number of total buffer units required and to provide guidelines for buffer allocation to achieve a given target throughput rate.