Also called pull system, two-bin system, card system
What is kanban?
A card or signal that tells the step before you to make or fetch more, so nothing gets made until it is needed.
What else it is called
- Other names
- pull system, two-bin system, card system
- In French
- kanban
Related entries
Understanding kanban
A fixed number of cards, bins or marked spaces circulating between two operations. When a bin is emptied downstream, its card goes back upstream and authorizes making exactly that quantity, and no more. Nothing is produced without a card, which means the work in process between the two steps can never exceed the number of cards you issued.
That last point is the real control. Managers usually try to reduce inventory by asking people to hold less. Kanban reduces it by removing cards from circulation, which forces the underlying problem, usually a long changeover or an unreliable supplier, to surface and get fixed.
It suits parts with steady, repeating demand. For a one-off job or a part ordered twice a year it is the wrong tool, and most plants end up running kanban for a family of regular parts and conventional planning for the rest.
In practice
Take one card out of a loop and see what breaks. Whatever breaks is the constraint you were storing inventory to hide.
Frequently asked
What is the difference between kanban and material requirements planning?
Material requirements planning pushes: it calculates what should be made from a forecast and issues orders. Kanban pulls: nothing is made until consumption downstream asks for it. Most plants run both, planning long-lead purchased material and pulling the repetitive internal parts.
How many cards should be in a loop?
Enough to cover demand during the replenishment time plus a margin for variation, then fewer each time you improve the replenishment. Starting too lean causes stockouts and discredits the method; starting generous and removing cards deliberately works better.