In Just-In-Time (JIT) systems, the subassemblies and parts required for final assembly are pulled in small batches from the supplying work centers whenever they are needed. One of the most popular methods used for implementing JIT is through the use of kanbans. Kanban means "card" or "visible record" in Japanese.

A single-card kanban system uses a withdrawal or "move kanban" to trigger production.

In the above system, work center A produces a part that is moved to the storage area in containers that hold a certain number of parts. Work center B pulls a container from storage when it needs the material and may return an empty container to the storage area. When B pulls the container, the move kanban is removed from the container and placed in the card rack at A. The move kanban in A indicates an authorization for A to produce another container of parts.

A two-card system has a move kanban and a production kanban. Suppose that work center B is using a container of parts that are next to B. The move kanban pulled from the container goes to the storage area. A full container is found, the production kanban is removed, and the move kanban is placed in the container. This authorizes movement of the container from storage to work center B. The production kanban is then placed near work center A as an authorization to produce another container of parts. When work center A is done producing a full container of parts, the production kanban is then placed in this container and moved to storage. ProModel is a very useful tool for modeling the demand order pattern and the flow of kanbans for pull production. ProModel has the ability to handle the flow of different entities at the same time linked together by logical rules. The optimum number of kanbans needs to be decided based on the flow requirements. The variation in demand over time necessitates use of alternate strategies in deciding the number of kanbans. ProModel's optimization module, SimRunner, can be used to optimize the number of kanbans under alternate strategies. Follow this link to learn more about ProModel and find out how customers all over the world are using ProModel to gain an advantage over their competitors.