Kanban (看板) is pronounced /’kan’ban/ and means ”visual board” – where kan means “visual,” and ban means “card” or “board”. Kanban is a concept developed at and used by Toyota. It is related to lean and just-in-time (JIT) production.
On the surface, there isn’t much difference between an average task board and a kanban board. Each of these boards has various columns that represent the stages that a card needs to go through before it is considered done. The real difference in a kanban board, is not the board itself. The board is just a visual indicator, the same as any task board, and the intention is still to get the cards to the “DONE”-state – that is, delivered to the customer so that they can use the features from that card.
Kanban is not an inventory control system. Rather, it is a scheduling system that tells you what to produce, when to produce it, and how much to produce.
So, what is the purpose of Kanban? In short it tries to:
- Visualize the workflow
Split the work into pieces, write each item on a card and put on the wall.
Use named columns to illustrate where each item is in the workflow.
- Limit WIP (Work In Progress) – assign explicit limits to how many items may be in progress at each workflow state.
- Measure the lead time (average time to complete one item, sometimes referred to as “cycle time”), optimize the process to make lead time as small and predictable as possible.
- Create flow focus on the throughput based upon the queuing theory.
- Identify and eliminate bottlenecks - Bottlenecks become clearly visible in real-time. This leads people to collaborate to optimize the whole value chain rather than just their part.
- Pull system features/tasks are pulled through the system instead of being pushed.
“In business, excess information must be suppressed. Toyota supresess it by letting the products being produced carry the information.”
After all, product development is information flow among many specialists. Stop communication, stop information flow, and you stop product development. Now, instead of “throwing the design over the wall”, engineers are taught to communicate concurrently with a team of upstream and downstream specialists – across functions.
Given that everyone agrees that communication is crucial to good product development, what is left o say on this subject? Actually, quite a bit, including the fact that more communication is not necessarily better. And that sometimes face-to-face communication is not as good as written documents. And that large-scale collocation may not necessarily be all it’s cracked up to be.
At Toyota we try to make every process like a tightly linked chain – where the processes are connected by information and by physical flow. There’s nowhere for a problem to hide. The chain never works perfectly. But if we know where our breaks are and our people are trained to fix the breaks, we get stronger every day in the company. It keeps us on our toes, it self-identifies muda and, five whys is our method to eliminate muda.
Glenn Uminger, Toyota Manufacturing Corporation, North America
The Power of Flow
Using cellular manufacturing, Toyota extended the concept of “one-piece flow,” or leveled flow, throughout its operations – even into supplier operations.
Toyota’s success starts with viewing the Product Development (PD) as a process. Like any process, PD has a cadence and repeated cycles of activity. Toyota has done an exceptional job of standardizing the PD process to bring to the surface the repeated cadence that allows continuous improvement through repeated cycles of waste reduction. Toyota has managed to “level the flow”, not only by eliminating waste (muda) but also by eliminating “unevenness” (mura) and “overburden” (muri).