Dear Gemba Coach,
How do you apply takt time in fields like services where customer demand is not known?
Customer demand is never known – no one I know has a crystal ball. The tools, such as takt time, are not there to calculate an answer so that you can deliver more easily without thinking. They were invented to make you think more deeply – for discovery, not delivery.
Toyota no more knows customer demand for a model than I know the real demand for this Gemba Coach column. What Toyota does know is:
- How models in a segment have previously sold at this period
- That the plant needs stable demand to perform
Takt time calculations start with best guesses about what model is penciled in for what country in what numbers, according to past sales and to competing models. I have no idea how Toyota actually does this, but I’m told they do this very carefully. Let’s think of the takt for writing a column. Full-time columnists write a piece every couple of days. Blogging rules of thumb say for fast growth post once a day, for slow growth, a couple of times a week, and for hobbyists, once a week. Most writers I know don’t actually post regularly.
If I post a column a week, I have a reasonable takt to sustain my community of readers. It’s demanding but not impossible, and much faster than most competing blogs.Producing Cars and Writing Columns
Takt time is calculated by dividing open time by averaged customer demand. Of course, there are many ways of doing this calculation – for example, do you take breaks of open time? What about changeover time? But that’s the whole point, there no one answer. Asking these questions makes you think about what, exactly, you’re trying to figure out.
I have no idea what the demand for my columns is, or whether there is one. I have no direct feedback on consumption. But I can figure that if I post a column a week, I have a reasonable takt to sustain my community of readers. It’s demanding but not impossible, and much faster than most competing blogs.
Although I have no idea of what “customer demand” would be like, I need a regular cadence to work serenely.
In Toyota’s case, once they’ve settled on a number of cars per period, they don’t calculate production rate but takt time: how often a car of that model needs to roll off the line to satisfy the demand. This makes them think about three hard problems:
- Line flexibility so that other cars are produced within an overall stable capacity
- Pull regularity from component suppliers so they produce steadily as well
- Spotting quickly when inventories accumulate because cars are not selling
When a model doesn’t sell as fast as it should, Toyota will see it faster than its batch-driven competitors. Not immediately of course because of the inventory in the supply chain, but by producing cars at a certain takt, one can check continuously whether a given model is being consumed at the same rhythm, or whether it accumulates unsold.
Similarly, I don’t exactly produce columns at takt – because I have many other activities and am not that flexible a writer. As a result, there is an inventory, a few weeks of columns when I simply don’t think about writing one. This means that some of the columns that are published are not topical when some debate or other arises in the community (of course, I can cheat, because we can keep columns in inventory cost free, so I can write a topical column right away).
Takt is not about the column, it’s about fitting the column within the takts of all other activities: gemba walks, book writing, conferences, study trips, social media posting, etc. By having a takt on all these activities I have to:
- Schedule my work accordingly – so I can do a lot of various things without too much overburden and burnout;
- Be flexible in terms of topic according to “kanban” – and here again, there is no kanban-like in production.
Thinking Upside Down
Because I try to come up with one column every week (with the variation of a small inventory), I can’t pick and choose topics according to what I want to write about – I’m simply not that curious or open-minded. Consequently, I take a question someone has asked me during the week and try to elaborate a more precise answer in the form of a column.
Calculating takts and running plants accordingly has given them superior understanding not just of how to run plants, but how to understand customer demand.Over the years this has led me to work on 1) my standards: clarifying what I know in repeatable ways and 2) explorations – thinking and analyzing topics I’m really not that sure about. Looking back, I can see that keeping to a takt of columns has probably helped me more than my readers. It has made me sustain and develop my own knowledge and understanding of lean topics.
And the same is true of Toyota. Calculating takts and running plants accordingly has given them superior understanding not just of how to run plants, but how to understand customer demand in different markets – and knowing where to put options on all cars (say, air conditioning) and where to cancel options (say, ashtrays) – or not. Takt time thinking brings you closer to understanding real customer demand, not just in volumes, but qualitatively as well: why do products sell faster than takt? Why do products sell slower than takt?
Takt time in service is just as powerful as in production because it gets you to think “upside down” and discover that, although you didn’t realize it, in many cases you’re batching, just as I am with this column. But to draw the full value out of takt time, you must look upon it as a discovery tool, not one more gimmick to help with spot delivery.