A Method for “Sweet Point” Operation of Re-entrant Lines

摘要

Production systems with infinite buffers typically have the lead time (IT) vs. throughput (TP) characteristic curve (CC) with a knee-type shape. Operating the system below the knee is not efficient, since TP can be increased without an appreciable increase in IT. Operating the system above the knee is also counterproductive, since IT becomes extremely large without a significant increase of TP. Thus, the desirable operating point is at the knee, which is why it is often referred to in practice as the “sweet point”. In this paper, using an empirical/analytical approach, CCs of re-entrant lines described by the bottleneck workcenter- based model with exponential machines are analyzed, the positions of the sweet point are quantified, and an open- and closed-loop job release strategies that ensure the operation at the knee are developed. The development is carried out in terms of the First Buffer First Served and Last Buffer First Served dispatch policies, although CCs for other policies can be investigated in a similar manner.