An Order Release Mechanism for a Flexible Flow System

Order release is where orders are released to the shop floor for processing. An Order Release Mechanism (ORM) can control order release, such that orders are selectively released so as to improve shop management and performance. This paper reports on the development of an ORM for a specific Flexible Flow System (FFS), where the primary criterion in running the system is flow time. The ORM determines what order to release when, and makes the routeing decisions for each order. Using a simulation model, the performance of the FFS with the ORM was compared to present practice without an ORM and an ‘off-the-shelf’ ORM from the literature, namely CONWIP. It is found that the ORM not only improves the mean time that orders spend in the shop under all load conditions, but also reduces the variance of this measure. It would be expected that the total time that orders spend in the system increases with the ORM, at least compared to immediate release, but at high load levels it is found that this measure also decreases. An analysis of variance suggests that the choice of ORM is more important than the choice of the dispatching rule used on the shop floor.