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Lean

Develop pull


Continuous flow is not always achievable through the entire value stream. Where there are breaks in the flow, operations cannot be coupled directly with the others in continuous flow. Rather than attempting to schedule these operations using a traditional scheduling function, allow these processes to be controlled by pull systems. Put in simplest terms, a pull system means that no one from upstream operations should produce products (or provide services) until the downstream customer asks for it.

There are many types of pull systems that can be implemented, each with different types of signal mechanisms. The most common is “Kanban,” which literally means “card.” In a simple one-card system, when product is started through a process, or when supplies are consumed, a Kanban card attached to the item is sent to the supplying process. Receipt of the card triggers the supplying process to replenish the exact item and quantity that was consumed.

The use of Kanban systems helps avoid traditional scheduling functions that are often inaccurate. When pull systems link stable processes that continuously flow, the result is a system that provides the item that is needed, when it is needed, and in the amount needed.