A kanban card is a communication tool used in the manufacturing field. "Kanban" is Japanese phrase meaning "instruction card" or "visual card." Most often, kanban cards are physical cards that are attached to a each part of a particular product. These cards move back and forth between the different sections of the production process, serving as a signaling system. Several different types of cards come into play in most kanban systems.
Withdrawal kanbans, also called conveyance kanbans or "move cards" are used to signal when a part is ready to move from one part of the production process to another. The card is attached to a prescribed number of parts, which are moved to the work area that requires them. Once the parts are used, the card is returned as a signal to send the same number of the same part back.
A production kanban contains a comprehensive list of everything the part requires in order to be completed. This includes the materials required, the parts required and the information included upon a withdrawal kanban. Essentially, a production kanban orders the production system to get started with production, as well as explaining what must be produced.
Express kanbans come into play when unexpected shortages of parts occur, to signal the need for more of a particular part so that the manufacturing process does not slow down. These are also sometimes known as signal kanbans. Essentially, they are used to trigger purchases.
Emergency kanbans are used to replace defective parts or to signal a sudden change in the amount of product that needs to be produced. Unlike express kanbans, emergency kanbans are used when a part does not work like it is supposed to or when the conditions of production change; express kanbans, on the other hand, are used to keep the original production conditions running smoothly.
Through kanbans are a combination of withdrawal and production kanbans, and are used when the two work centers for these kanbans are located side-by-side, in order to speed up production. For instance, if the storage area for components is right next to the place where the product is assembled, having a single kanban to pull the parts and run them through the production process saves time.
A supplier kanban goes directly to a supplier -- a company that sells materials to the manufacturer -- and enters the supplier's kanban system as a representative of the manufacturer.