Overproduction (waste) is one of the biggest tenets of the Toyota Production System. In this principle, Toyota recommends using pull systems to avoid producing overproduction.
Section II: The Right Process Will Produce the Right Results
Principle 3. Use “Pull” Systems to Avoid Overproduction
■ Provide your downline customers in the production process with what
they want, when they want it, and in the amount they want. Material
replenishment initiated by consumption is the basic principle of just-intime.
■ Minimize your work in process and warehousing of inventory by stocking
small amounts of each product and frequently restocking based on
what the customer actually takes away.
■ Be responsive to the day-by-day shifts in customer demand rather than
relying on computer schedules and systems to track wasteful inventory.
A tool Toyota uses to prevent overproduction is called kanban. A kanban is a sign. It could be well placed card signally that one area is about to run out of parts, or it could be an empty bin, indicating it is ready to be filled again with a specific number of parts. The kanban system is used for managing the flow and production of materials in a just-in-time system.
What is interesting is that even today, with all the electronics and computers at their disposal, you can walk into a Toyota factory and still see simple cards, and empty bins being used to manage production on the plant floor.
While kanban is a useful tool for managing inventory, Toyota still strives to eliminate the need for cards and signs, as inventory of any kind is seen as a form of waste. In Toyota’s view that is the greatest challenge. To create a learning organization that will find ways to reduce the number of kanban and thereby eliminate the inventory buffer all together.
This makes me wonder if there are ways we can reduce, or eliminate the kanban system we often use on our agile projects. The card wall.