The Kanban Method was created by David Anderson. A full description can be found in the seminal book “Kanban: Successful Evolutionary Change for Your Technology Business”.
This is because it uses similar ideas to manufacturing’s kanban (such as in the Toyota Production System): a kanban, roughly translated to ‘signal card’, is used to identify when a point on the production line is ready for more work. This is known as a ‘pull system’.
What is a pull system?
Here is an example of how a pull system works:
- My job on the production line is to fit the wheels on cars
- I have two stacks of wheels next to me
- A car chassis comes along … and I fit the wheels … and move it on the production line
- Another car chassis comes along … I fit the wheels … and move it on the line
- Another car chassis comes along … I fit the wheels (using up one of the stacks of wheels next to me) … and move it on the line
- The guy in the wheels department sees that I have used one of my piles of wheels and produces another stack of wheels which he sends on to me
- I continue to fit wheels onto cars
In this example, the level of wheels I receive is dictated by the number of wheels that I already have. I cannot become overloaded with inventory, because the delivery of more wheels to me is dictated by my available capacity; when I have two piles of wheels, they know to stop producing wheels. I always have enough, but never too many. Equally important, should I stop working for any reason, the team that produces the wheels stops making them. In most companies, they would be producing wheels regardless of what I was doing, and my piles of wheels would just keep growing and growing.
Of course, money is tied up in any parts that have been made. The more inventory, the more money is tied up. Companies that don’t use a pull system, who just keep producing parts regardless of the demand from the other areas of the company, tie up a lot of money in inventory and gamble that these excess parts will be used. What if I had 1,000 wheels next to me but the company changed the design of the wheels?!
A pull system helps systems become ‘lean’.
So what is The Kanban Method?
In short, The Kanban Method has 4 foundational principles and uses 6 core properties to create a set of behaviours that help organisations be lean.
- Start with what you do now
- Agree to pursue evolutionary change
- Initially, respect current roles, responsibilities & job titles
- Encourage acts of leadership at all levels
Six core properties
1) Visualise workflow
Visualising your work enables you to understand how work proceeds through your system. This enables you to spot areas that need change. A common approach is to use cards on a board – with different columns for each step of your process.
The Kanban Method encourages you to start with what you have now. Don’t change your processes immediately, just identify your existing practices and processes. For example, how can you visualise the different types of work you do? How can you show who is working on which item? Can you display which items are blocked? Or those that relate to different areas of your business or different customers? (To name just a few)
2) Limit Work In Progress
Limiting the work that you have in progress at any one time helps you implement a pull system: work cannot be pushed to you just because someone before you in the chain has finished their work; it will only come to you if you have capacity. This has the benefit (as explained above) of not producing inventory that has potential to be discarded. It ensures that teams are working on the most appropriate item that the business needs at all times.
3) Measure and manage flow
By measuring the flow of work through your process, you can identify problems. Every process has at least one bottleneck and your system can only work as fast as your slowest bottleneck. So make changes to your processes in an attempt to improve flow. Measure the changes … then repeat the process … again … and again – to continually improve your processes.
4) Make process policies explicit
If you don’t know the rules, it is difficult to improve a situation. The Kanban Method asks us to make our processes clear … then you can have an objective discussion about improvements.
Explicit policies include identifying what must happen before an item can be pulled into a particular part of the process (known as ‘entry criteria’), defining what finished looks like (known as a ‘definition of done’), and acknowledging how you will action each of the different types of work you receive (known as ‘classes of service’).
5) Implement feedback loops
Do you review your performance and feedback regularly? You probably already do daily stand-ups and retrospectives: both of these are feedback loops. But, armed with data on the flow of work you now have more feedback. You are encouraged to get wider data about the company as a whole, and your departments contribution to the overall performance. Do you get feedback from customers and review that? What about other teams within your company that you work with? And stakeholders? There is a lot of feedback available out there: are you listening to enough of it?
6) Improve collaboratively, evolve experimentally (using models and the scientific method)
Improvements should not be revolutionary (remember, you’re starting with what you have already); you should look to make continuous, evolutionary and incremental improvements. The scientific method puts forward a theory then tests it – you should then keep what works and discard what doesn’t.
One particular area of improvement that will improve the flow of work through your process is to reduce the variations in the work that you have: when the work you do is similar, you should be able to deliver consistently; when it is varied, it is difficult to be consistent. Example of sources of variability are:
- Differing sizes of work items (e.g. putting tractor wheels on is going to take longer than car wheels)
- Differing work types (for example, asking me to work on wheels one hour, then fit doors the next hour, then windscreens the next is going to cause me to be slower than doing one type of work)
- Differing classes of service (e.g. having urgent work come in where I have to drop what I’m doing is going to cause the dropped work to take longer; whilst the urgent item is done quickly – variation)
- Having to rework items (e.g. doing a job right first time saves time in the long run)
- Accepting unknown work (e.g. agreeing to undertake work that is ill-defined)
- Problems with your working environment (e.g. if the factory keeps having power cuts, I’m going to find it difficult to work)