THE TOOLS CORNER – In this new series, we go back to basics, offering a guide on how to implement some of the most important lean tools and explaining why they are so clever. First up, Kanban.
Words: Michael Ballé, lean author, executive coach and co-founder of Institut Lean France.
Main photo courtesy of Alliance-MIM
A Kanban is originally a signboard, usually printed cards in plastic cases. Every box of items that flows through a lean pull system carries its own Kanban card. Kanban come off of items that have been used or transported, and go back, as orders for additional items, to the preceding process.
A card, a “Kanban” (signal), is placed in each component’s container. When a team member takes the first part out of the container – say a headlight cover – he puts the card in a mailbox. The cards are collected regularly throughout the day, and sent back to the supplier as orders of new components. The instruction for the supplier is then to supply one part when they see the customer has used one.
In its early days at Toyota, Kanban was a practical response to a very difficult problem. In order to follow customer demand more closely, Toyota engineers wanted to make one car – say a model A – only when they’d sold a model A.
On top of this, as they were capital poor, they wanted to make several different model (A, B and C) on the same production line. What is more, they wanted to produce the cars in the order of customer demand.
A production line would be scheduled something like this:
For this to happen, each workstation needed all the parts to make every model – the A sedan, the B hard top, the C van. Therefore, they needed very small containers of each part. Components had to be brought to the line according to the idea of “use one, get one.”
The simple yet transformation Kanban cards put tremendous pressure on the entire production system, with far-ranging implications:
There are three key phases in the use of Kanban (check out the video below to see an example of this):
Because the sequence of decisions you make matters disproportionately to the final results.
Think of it this way: we’re starting this new series on basic lean tools on Planet Lean. We could have started with a batch, listing all the basic tools. As a “supplier,” I could then choose which one to start with, then the next and so on.
Human nature being what it is, I would start with the tools I’m most comfortable with, and leave the hard cases for later. As a result, I’d write what I’ve always written about.
If we do it using Kanban, we start with, well, Kanban, and once that’s done we ask ourselves what the next tool should be. This might well be SMED, or Standardized Work, not necessarily topics I can easily write about. Since I need to deliver to Kanban, I will then have to face my difficulty and learn how to do it. And that’s kaizen.
The end result will be very different as well, as the list of tools will grow organically, and having solved some early problems with the first attempts, the later ones will be easier to write – kaizen again.
As a producer, working with Kanban completely changes my relationship to the work. I can see, very visually, that 1) I have to deliver a piece of work at a certain tempo (as opposed to plow through a list how/when I can), 2) I have to make every single piece good, 3) I can’t choose in advance the parts I like and leave the tricky ones for later (I need to face every issue now), and 4) I probably need a “chain of help” to get me out of real difficulties when I’m stuck.
Sticking to Kanban will open up the real potential of kaizen:
The spirit of kaizen is to bring value closer to the final customer. Without Kanban, you can be practicing what you believe is kaizen, but you actually have no compass, no direction-setting, practical, visual, here-and-now tool to see whether the new idea is a step in the right direction or just a random change.
Before calling it the Toyota Production System, Toyota engineers used to refer to their improvement system as the “Kanban system”. There’s only one conclusion: if you’re not using Kanban, you’re probably doing something great and improving things here and there, but you can’t call it “lean.” Kanban is a harsh discipline, but it’s the first step into the bigger world of true continuous improvement.
Michael Ballé is co-founder of the Institut Lean France. An associate researcher at Telecom ParisTech, he holds a doctorate from the Sorbonne in Social Sciences and Knowledge Sciences. Michael is a best-selling author and an engaging speaker, and managing partner of ESG Consultants. He also works as a lean executive coach in various fields, from manufacturing to engineering, services to healthcare. His latest book, The Lean Strategy (co-authored with Dan Jones, Jacques Chaize and Orry Fiume) is available here.