Decoupled Lead Time in finite capacity flowshop: a feedback loop approach

Recently studied, Demand Driven Material Requirement Planning (DDMRP) seems to offer good performances. Its buffer parametrization is done by a dynamic adjustment considering the demand evolution, but not the workshop state. Several papers deal with lead time variability and take into account its variations in the parametrization of traditional material management methods such as Material Requirements Planning and pull flow systems. This paper considers lead time variability and proposes a dynamical adjustment of the decoupled lead time of the DDMRP. When applying it to a modified flow shop with a competence bottleneck, results show that the dynamic adjustment of the buffer sizes reduces stocks, while assuring a decent service level. We also find that it increases workload, to an extent where it can be better not to cross a certain limit that has to be determined, otherwise lead times increase drastically.