Would you do it?<\/strong> No.<\/strong> We buy bread when we need it, in the amount we need, and try to keep our inventory low…but more on that later.<\/p>\n\n\n\n The reason I’m talking about bread is because it’s something that almost everyone understands, and should make explaining Kanban that little bit easier.<\/p>\n\n\n\n Plus I really like bread.<\/em><\/p>\n\n\n\n This is not intended as a lecture or to give you a creepily in-depth knowledge of Kanban and the history behind it. I am not a teacher in that sense, and while it might be cool to know that “Kanban means card and has something to do with Toyota and a guy named Taiichi Ohno, etc.” \u2026, I\u2019d rather use this post to actually examine why we should care about Kanban at all.<\/p>\n\n\n\n So in this blog post, we will visit a bakery. As it is also the Introduction to Kanban<\/em>, we will look at means to visualize the flow of work, find ways to tell the other process steps to “do more”, and discover a little something called “work in progress”, all while eating donuts!<\/p>\n\n\n\n\n\n\n\n When you think about making a sandwich, it’s generally “make sandwich” and that’s where it ends. But there are more steps involved, so I’ve broken down the process a little bit to help show what process steps<\/em> are:<\/p>\n\n\n\n Buy bread \u2192 Cut bread \u2192 Assemble sandwich \u2192 Eat sandwich.<\/p>\n\n\n\n Now I know that “Assemble sandwich” is a bit generic – that’s there because I need variety in my life, and make different sandwiches of different complexity.<\/p>\n\n\n\n Anyway, if we break the above flow down a little we actually have:<\/p>\n\n\n\n It’s OK to judge my sandwiching. I’m German and confident in my efficiency, but the above won’t help you with understanding the value of Kanban because it’s too simple.<\/p>\n\n\n\n So we’re going to look a little further upstream <\/em>at the bread manufacturing itself, which is where my supplier (the bakery) has to go through a similar process. They need to make sure they have the ingredients, then create their product, and eventually ship them.<\/p>\n\n\n\n In order to turn ingredients, time and energy into delicious bread and buns, they also have several process steps<\/em> because they have a load more variables to try and factor in (order volume, time, machining capacity).<\/p>\n\n\n\n But even though they need to work much more efficiently than me, they also try to keep their inventory low.<\/p>\n\n\n\n All baking starts by figuring out what you’re going to sell, which can either be driven by customer orders (i.e. whole sale) or by what you know you can sell in your store (i.e. direct sales). Either way from the process perspective, “we need X” is actually an order, and first thing that happens is that the order is accepted. From there they look at what’s in progress and when the order needs to be completed, and then the bakery magic can begin. When it’s done – it’s finally packaged and shipped out.<\/p>\n\n\n\n Kanban<\/em> looks at the flow of the order in a perspective that starts with the backlog (order accepted), to pre-flight (mix dough), then in progress (baking), and then completion (deliver to customer).<\/p>\n\n\n\n So we’re already off to a good start because we know what all the main stages are that happen from the request coming in to the freshly baked goodness going out!<\/p>\n\n\n\n Let’s spice it up, we will now visualize this chain. By creating a column for each process step you have actually created a Kanban board, and it would look like the illustration below. If you’re interested in “what’s beyond visualization”, check this blog post<\/a>.<\/p>\n\n\n\n Kanban is about visualizing the process and the flow of work.<\/p><\/blockquote>\n\n\n\n So far so good, but couldn’t we just do that by ourselves with a pen and paper? Good question, let’s add to our example.<\/p>\n\n\n\n Since the bakery’s products are so delicious, they quickly became the talk of the town (I was about to write “went viral”, but doesn’t sound too good when talking about edibles, doesn’t it!?). The demand went through the roof, so instead of being able to take care of the orders pretty much as they arrived, Betty the Baker started writing the orders down on Kanban cards to keep track of them.<\/p>\n\n\n\n She even used different card colors to indicate the relative priority <\/a>of the orders (note that for the sake of simplicity, all orders have an equal number of items, require the same effort and are equally complex to make).<\/p>\n\n\n\n Now she has a backlog <\/em>which gives an easy overview of what’s going on. This is our Commitment<\/strong>. It’s the same as when we make a ‘to do list’, but there we’d need filters do achieve this quick overview:<\/p>\n\n\n\n Kanban is also about visualizing the amount of work per workflow status.<\/p><\/blockquote>\n\n\n\n\n\n\n\n Wow, this is now way more orders than we can immediately deal with (the experts would call this “reaching capacity limits”). So what do we do? We can mix pretty much all the dough at once, and we have access to additional delivery vans – so do we just go for it? Make lots of money? Buy the shiny, or get tickets to that thing we like<\/a>?<\/p>\n\n\n\n From a management perspective, even though we know the oven is limited, we should aim to minimize downtime between bakes… right? We were often told at business school that switching costs<\/em><\/strong> can be reduced by larger batch sizes…and then of course there are those economies of scale <\/em><\/strong>and economies of scope<\/em><\/strong>. But what does that mean? If we know the solution, why don’t we just do that? <\/p>\n\n\n\n Well because we’re using a bakery to explain this, you already know that the oven limits what is possible. But for arguments sake, even if the dough wouldn’t turn bad just sitting around waiting to be used aaaaand even iff we had a quantum oven with infinite space, our service quality would deteriorate because we still only have the same number of bakers.<\/p>\n\n\n\n On the flip side, we don’t actually want to be processing one order at a time either, we want to be making the most of our available capacity, because if we processed each order in series, then that leads (ha!) to longer wait times.<\/p>\n\n\n\n In this (theoretical) state where we can do everything at once, our customers would still have to wait a very, very long time for their orders to arrive. Check this illustration (kudos to Henrik Kniberg for the idea<\/a>), comparing the leadtimes for the preparation of smiley donuts:<\/p>\n\n\n\n
Obviously not, aside from the fact that it’s an insane amount of bread, it really doesn’t have a very long shelf life, it would start to mold, and your love affair with bread would soon end. So when is the right time to buy more bread?<\/p>\n\n\n\nInstant Feedback \u2013 Visualizing the Flow of Work<\/h3>\n\n\n\n
The KanBun Bakery<\/h2>\n\n\n\n
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Board_Only-Columns.png\")
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Board_Backlog-Filled.png\")
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Batchsize-vs-Leadtime.png\")
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Board_WIP1.png\")
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Board_WIP2.png\")
![\"\"](\"https:\/\/metaworks.eu\/wordpress\/wp-content\/uploads\/2020\/04\/KanBun_Board-with-Buffer.png\")