Visual Management ◾ 93
to be refilled. In a hospital pathology lab, it could be a special
tray that holds frozen sections waiting to be read.
A kanban is useful for changing the flow of work and infor-
mation from a “push” system to a “pull” system. A push system
is one in which the upstream process sends materials to the
downstream process whether or not the downstream process
needs it. A pull system is one in which the downstream pro-
cess requests materials when it’s ready, and that request is a
trigger for the upstream process to begin work. Push systems
create all manner of waste. Pull systems reduce it. Pull systems
help create flow.
An example of a push system in a factory is when the
guys making bumpers crank out hundreds of units even ...