What is Flow (and Takt)?
What is flow? How do we takt-fully create it?
Hi, I’m Nate Barber. Welcome to the 6th video in our 10-part series celebrating Opgrade’s 10th anniversary. Thanks for watching, and thanks for celebrating with us!
Last week we talked about value stream mapping, and how doing so makes your processes visible. It lets you see the activities in your work that add value, and those that do not. Value stream mapping, and its preceding principle, defining value, are largely about understanding your organization and crafting a vision for where you want to take it.
The next, and third Lean principle is Flow. Flow is about designing processes where work progresses, or flows, through the system steadily, and predictably, one order at a time. Just like in a well running assembly line. Or with my preferred analogy, just like in a steadily flowing river that is free from dams. A system that lacks flow is more like a river stopped up along the way with many little dams. Those dams are pools of work, stockpiles if you will, where work has stopped for one reason or another, often because the work is done in batches.
Batches, especially large batches, are the antithesis to flow. Back in the 50s and 60s, American automakers were especially guilty of this. Coming out of World War II, American consumers were becoming more sophisticated and were demanding more variety in the products they consumed. At the time, the Big 3’s solution to variety was to minimize production changes by making huge batches of cars in giant runs. This worked for the American automakers because they had both 1) the capital to invest in large batches of raw materials and 2) the space to put the giant batches of cars they produced. Every change to production, though, required a long, and therefore expensive changeover, so of course, changeovers were avoided and batches got bigger and bigger.
We Americans justified this because when we saw the success Ford had with the Model T at the River Rouge plant, we saw scale, so we ran with the concept of economies of scale. When Taiichi Ohno and Toyota toured Ford’s River Rouge plant, they also saw the scale, but they also saw all the waste that came with these “economies” of scale. What they saw that Ford did right was the concept of flow. To quote H Thomas Johnson, Taiichi Ohno saw that “Ford's plants conserved resources by having processes linked in a continuous chain and by running slowly enough so that people could stop and fix errors when they occurred.”
You see, in perfect flow, value-added work does not stop because all the non-value-added wastes have been eliminated. Perfect flow is that perfect assembly line in your imagination, even for work that you might not traditionally think belongs in an assembly line. Perfect flow also doesn’t require any inventory between steps because each process step is perfectly timed, such that as each step is finished, it receives the preceding step’s work product. Also with perfect flow, the customer gets exactly the amount they want, when they want, at the quality they want, because the river is takt-fully sized to meet that demand. More on that in a minute.
Now, even if you have established perfect flow in an assembly line like manner, but you still have long changeovers, you’ll still have to accumulate large batches at the end of your system to meet your customers’ demand for variety. Even if you don't have many small dams along the way, you still have a giant Hoover Dam at the end. What Taiichi Ohno realized is that flow and variety need to be able to go together. We need to be able to switch between products or services while the river is still flowing, all without compromising on quality.
To do this you need two things. First, you need to continuously work reduce the change overtime between batches. You also need to train and empower your people to be able to handle variety in the middle of a batch, instead of waiting for another batch. If you can drive the change over time to almost zero, and your people can handle variety order by order, item by item, then the whole need for batching disappears and you get what we call single-piece flow, or one-piece flow. Each process step produces only what is needed for the next step, in a just-in-time manner.
By both reducing batch sizing and equipping and empowering their employees to handle variety mid-production, Toyota exposed the fallacies and wastefulness of the American “economies” of scale. Instead of going for a production at scale, the Japanese were instead able to scale their production to exactly meet customer demand. They sized their river to meet their customers’ needs. To do this they use the Lean concept called takt.
Takt is the German word for stroke, or bar, or measure. It’s the rhythm of the music. Imagine a conductor in front of a symphony, and every time the conductor moves their hand down on the downbeat, that would be the takt. Takt has basically the same meaning with regards to flow and production. Takt is the rhythm provided not by the conductor, but by the customer. It is the customer’s drumbeat, or even heartbeat.
This, though, is where that metaphor gets tricky. When we think of drum beat or heartbeat, we think beats per minute. We think of it as a rate. In Lean, takt is measured as a time, the time between beats, the time between items produced or services provided. Takt is therefore not beats per minute, but minutes per beat. This is more helpful in production, because it tells you exactly how long you have to complete any given step.
For example, I've been told that Toyota’s takt for their Tundra plant here in San Antonio, TX is one minute. Does that mean they produce an entire truck in one minute? Of course not. It does mean that every step in the process is sized to one minute. It may take more than 1,000 minutes to make a truck, but if each step takes one minute, and every minute a truck moves forward to the next step in the line, then that also means every minute a truck rolls off the end of the line. And if you're ever in San Antonio and would like to go visit the Toyota Tundra plant with me to see this remarkable feat, I would love to be able to take you.
So how do you calculate takt time? Well, you simply divide the time you have available to work by the average number of things you actually sell to customers in that same timeframe. For example, if in a given week I needed to produce an average of 35 of these videos, and my team works a 40 hour week, then the takt time would be 40 hours divided by 35 videos, which is 1.14 hours per video or 68.6 minutes per video. Now, if you're anything like me, between emails and phone calls and meetings, in a given 40-hour week I'd be lucky to get even 35 hours of work in. That means my real time available is just 35 hours, and my real takt time is one hour, or 60 minutes per video.
Now again, does that mean we have to write, rehearse, film, and post produce a video in just 60 minutes? Nope. But it does mean that each step cannot take longer than 60 minutes. If overall, it takes about five hours to make one of these, which it does, then if I had to produce 35 of these per week, I know I would want to create flow by breaking the process down into five steps, each lasting one hour. Man, making these videos is very much like eating wrist watches, it’s very time consuming.
I've been told I need to have a drummer following me around to provide rim shots for my jokes on demand. Any volunteers willing to provide the drumbeat to my jokes? Get it? Takt. Drumbeat. The best jokes are the ones you have to explain.
Well, that's it for flow and takt. If you take anything from this video, understand that flow comes from reducing batch sizes and equipping your teams to handle variety mid process, even in processes that have nothing to do with manufacturing. It may not be easy, and sometimes it may not even be possible to achieve perfect flow, and that’s where Pull and Kanban come in. Tune in that next week.
Until then, thanks for watching, and thanks for celebrating Opgrade’s 10th anniversary with us.