Buffer allocation vs. sequencing optimization: which of the two is most effective to improve the efficiency of assembly lines?

In the paper two popular techniques able to improve the efficiency of mixed model asynchronous assembly lines are compared: the allocation of buffers within work centers and the optimization of the sequence of models entering the line. The comparison has been performed on a set of benchmark instances related to the MALBP (Mixed-model Assembly Line Balancing Problem). In fact, the buffer allocation problem (BAP) and the sequencing problem (SP) are strictly connected to the MALBP, because balancing decisions, buffer allocation and sequencing optimization have a direct impact on the line throughput. The presented approach allows to simultaneously solve the BAP, the SP and the MALBP for asynchronous unpaced lines. In this way, by an opportune design of experiment, it is possible to compare the different solutions found for the benchmark instances and to quantify the impact of buffer allocation and sequencing optimization on the quality of the solutions.