Kanban is one of the lean tools and is Japanese for “signal card”, which refers to its function to signal a demand for more supplies.
When supplies are running low at a workstation or stock area, the Kanban card goes to previous area to signal supplies are needed. Parts or material are then ordered or produced to arrive before the previous delivery runs out, this way work can be done at continues flow without interruptions.
In its simplest format the Kanban is a card with an inventory number that moves with the parts. As soon as a part is taken from the box or container, the card is send up the supply chain as a request for a new container with parts. No parts are ordered or produced unless there is a Kanban card request for them.
In the 1940’s and 1950’s, Taiichi Ohno applied Kanban in the production at Toyota to support a pull production.
In the 1970’s Kanban was promoted in the manufacturing industry as one of the lean manufacturing tools, but is seen as a tool that can be applied in various industries today.
When looking at Kanban it can be split up in steps to make it simpler and easier to understand, this will be the workflow.
- Each process step has two parts, a queue and in progress.
- Each process has a limit of items it can have in its queue.
- Previous process will push material into the queue and the following process will pull material into in progress.
- If one of the process steps reaches its limit, the previous process step must stop until it is cleared.
Just explaining the above to people is not enough, easy identifiable visual instructions need to be available for it to work. It is here the Kanban cards described earlier come into effect, they are the once signalling every time inventory need to be moved or ordered.
General Rules of Kanban
- Processes may only withdraw items upstream as specified on the Kanban
- Processes may only send items downstream as specified on the Kanban
- Items are produced or moved unless there is a Kanban
- All items must have a Kanban with them
- Defects and incorrect amounts are never sent downstream
If you are interested in lean and how to make your organisation more efficient, then our 5S Training might be interesting for you. 5S is usually one of the first elements implemented when starting out with lean, as it gives a great foundation for further improvements.
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