ABSTRACT
Let’s summarize what we have learned so far about card-based systems (Chapters 5 through 7). First, kanban systems are a powerful tool in internal supply chains, where different convergent flows of products/services need to be coordinated. But a kanban system will only control the flow of independent product/service flows through the shop floor-i.e. shop floor control-if kanban loops are decoupled from each other. We characterized this kind of control as an inventory control problem. If a kanban system is used to control the flow of a specific order, we run into a problem with the propagation of information from station to station. In fact, in an order control problem, a kanban may represent not the direct load at a station but
the indirect work still upstream and yet to arrive at the station. This means the second station should allow for twice as many kanban cards as the first station, the third station should allow three times as many cards as the first station, and so on. The further downstream we go, the more indirect load there is, and the more kanban cards have to be allowed for. Since a kanban system is controlled by the last station in the line, control becomes complex in an order control problem.
