There are many types of kanban. A kanban could be cards, bins, containers, trays, carts, spots on the floor, golf balls, ping pong balls just to name a few. What’s the best kanban signal?
First, what is a kanban? A kanban is simply a signal used to authorize production in a production system. Any method of signal works can work well if we are disciplined to follow and maintain the system. A kanban is typically tied directly to the physical parts making it easier to keep in synch with demand. As parts are pulled for consumption, this signal is sent to the supplying workstation or source as authorization to make more parts to replace the ones used.
However, before we automatically jump to using any kanban system just because we believe it is the “lean” thing to do, is there a specific problem or need in the first place? This is one of the most common mistakes made on the lean journey. We see a lean technique and rush to put it in use everywhere we possibly can. It’s like holding a hammer and running around looking for nails to hit, soon everything starts looking like nails. We rarely take the time to really understand our problems or needs before we act.
What if we can produce products for our customers in one week while the customer delivery expectation is two weeks, would we set up a kanban system to replenish parts? No, just build to the actual customer order which is the best kanban signal of all.
In this example, there is no need for a typical kanban replenishment system at this time. But if our leadtime extends beyond our customers delivery expectation, we certainly have a need to set up a production system to satisfy our customer with the least amount of inventory. After gaining a better understanding of the problem, we might consider using a kanban system while we are working on reducing our production leadtime within our customer delivery expectation.