Wait, what, three kanbans?
Kanban conversations can become confusing, and one of the reasons for this is that when we use the word ‘kanban’ we could be referring to three quite different concepts. See for example this post if you want a deeper dive into the whole ‘what’s in a name’ conversation.
Kanban One — the original kanban
Kanban, 看板 in Kanji and かんばん in Hiragana literally means ‘signboard’, however the word ‘kanban’ has a specific technical meaning, and as we will see there are some powerful concepts that flow from this one word.
Kanban, in its original sense could be defined as
“a visual indicator that a process is in need of replenishment”.
Lets take a look at a rather over-simplified example to explore this definition:
Imagine you are a worker on a factory line. Your job is to screw two widgets together, as they come along the assembly line. To do this you need screws. Lots of screws.
In this “two bin” inventory management system you, the line worker always take screws from one bin. In the image on the left this will be the front bin, the one that has been partially emptied. When you have used all the screws and this bin becomes empty two things happen:
1. You start taking screws from the full bin. The back bin in our image. You can do this as soon as the front bin is empty, meaning you don’t need to wait, you can simply keep right on doing your job.
2. The team responsible for supplying your workstation with screws re-fill the front bin.
When you run out of screws in the back bin you switch to the front bin and the back bin is filled. And so on…. and so on
In this example the empty bin is the kanban. The visual indicator that a process (in this case the widget screwing process) is in need of replenishment. Although a very simple process, some extremely powerful concepts flow from using even the most basic of kanban systems.
1. Visual management. The empty (and emptying) bin of screws provides an exact visual representation to the screw-supplying process of how fast screws are being used, and when replenishment may be required.
2. Pull system. The screw supply is not dictated by the supplying team, rather the flow of supply depends on the rate at which screws are used.
3. Just in time delivery. A bin is re-filled when it is empty. So from the point of view of the team supplying the screws they can refill a bin only when it becomes empty. They cannot simply dump a truckload of screws, a batch can only be supplied when it is needed, i.e. just in time.
4. Limiting of Work in progress. Because of the Just in Time delivery system established, there is now no reason for the supplying process to stock up on container-loads of screws. Inventory is ‘pulled’ as the work is pulled.
Kanban and Toyota
Kanban was an integral part of Taiichi Ohno’s Toyota Production System, a system that has profoundly affected the way work gets done in the 21st century. See my blog Lean in a Nutshell for more on this subject.
In the original Toyota system kanban were physical cards:
There is a lot of detail on this early Toyota kanban card, and the system is now largely electronic, however the basic principle remains. The kanban card is a visual indicator that a process (the Toyota parts supply process in this case) is in need of replenishment.
Kanban Two — kanban for software
This second kanban speaks to the kanban body of knowledge; kanban as applied to software development.
Starting with work David Anderson did with a services team at Microsoft in the mid 1980s , a body of knowledge has developed around kanban as it can be applied to software development.
This work was built upon by Andy Carmichael who co-authored with David Anderson the ‘Essential Kanban Condensed’ booklet (left).
Six kanban Core Practices (CP)and four Foundational Principles (FP) were described by Mike Burrow’s in his book Kanban from the Inside (which as an aside covers way more than kanban and is well worth a read). These are:
- CP1: Visualize.
- CP2: Limit work-in-progress (WIP).
- CP3: Manage flow.
- CP4: Make policies explicit.
- CP5: Implement feedback loops.
- CP6: Improve collaboratively, evolve experimentally (using models and the scientific method).
- FP1: Start with what you do now.
- FP2: Agree to pursue evolutionary change.
- FP3: Initially, respect current processes, roles, responsibilities, and job titles.
- FP4: Encourage acts of leadership at every level in your organization — from individual contributor to senior management.
Why is this body of knowledge called kanban since it speaks to general lean practices and principles?
I have no idea to be honest. The connection between kanban as it was developed by David Anderson, Andy Carmichael, Mike Burrows and others bears almost no resemblance to the inventory management system kanban that was pioneered in Japan in the 1950’s. For whatever reason the name has stuck and I guess its just one of life’s quirks!
Kanban Three — David Anderson’s Kanban Method
The Kanban Method outlined in David Anderson’s ‘blue book’ has since been expanded considerably. The best way to get your head around this third kanban is to think of it as a framework. So in commercial terms the Kanban Method would compete with SAFe. Take for example the system of inter-connected meetings.
This obviously goes beyond principles and practices, this is an over-arching, prescriptive system for managing work. Another example — the Kanban Maturity Model targets the Enterprise transformation market.
Choose one, two or heck do all three.