Kanban is a Japanese term referring to sign board or visual signals that authorize the production or movement of items in manufacturing environment. A Kanban system is a self-regulating pull system that leads to shorter lead times and reduced inventory. Kanban systems are typically applied to items that have relatively constant demand and medium-to-high production volume.
It works on the basis that each process on a production line pulls just the number and type of components the process requires, at just the right time.
Kanban system is similar to the human body control system as instructions send by brain to body parts, a kanban system gives instructions for control of production to every work area in a lean production system. It connects information flow with material flow by attaching kanban cards to the actual goods.
The Kanban system was developed by Taiichi Ohno of the Toyota Motor Corporation for realizing Just in Time (JIT) manufacturing. Mr. Ohno was inspired by the product replenishment methods at American supermarkets, the way shelves were restocked with goods only after products were consumed by customers.
Kanban systems focus on stopping overproduction thus, preventing creation of large inventories and reducing waste. Kanban enables a pull-based replenishment in manufacturing setups.
A kanban is a card with an inventory number which is attached to a part and before installation, the kanban card is detached and sent up the supply chain as a request for another part. A part is only manufactured (or ordered) if there is a kanban card for it. Few generally accepted rules are
- Downstream processes may withdraw items in the amounts specified on the kanban card.
- Upstream processes may send items downstream as per quantity and sequence as per kanban.
- No items are made or moved without a kanban.
- A kanban must accompany each item at all times.
- Defects and incorrect amounts are never sent to the next downstream process.
- The number of kanbans should be monitored carefully to reveal problems and opportunities for improvement.
