Kanbans are used in Lean
Production. A kanban system
is a 'pull' system of production as opposed
to the traditional 'push' system. Products
are made in small batches to meet the immediate
demand. Each batch will usually only be
sufficient for a few hours of consumption,
The Kanban is a card (or occasionally some
other device) that authorizes production.
When a batch is made the kanban travels
with the batch to the next production stage.
When that production stage starts to use
the batch the kanban is returned to the
producing station, thus authorizing the
If a producing station does not have any
kanbans it does not produce anything. Thus
if demand slows down, or stops, the production
rate will slow down or stop. The producing
station will not continue to produce to
'get ahead'. The kanban system reduces inventory
and forces stations to be more efficient,
responsive and achieve faster changeovers.
The use of small batches achieves a more
regular flow of work and thus actually reduces
the amount of stockouts.
The system described is a simple 'single
card' systems. There are more complicated
variations on this.