Takt Time Is Local

There was an interesting search in my logs today.

[does a system have a single takt time or multiple]

I always figure that if one person is looking, others are also curious, so let’s address it and maybe there will be a better search result for the next Googlenaut out there.

Takt time is local.

It is calculated based on the demand from your customer.

This is a critically important concept because for takt time to be of any use, it has to be relevant to the people who are actually doing the work.

Example 1:

A factory has four final assembly lines that feed into shipping.

There are 420 minutes of working time in the day, and total aggregated leveled output is 350 units of production.

What is the takt time?

For shipping, it is straight forward. The customer takt time is:

420 minutes / 350 units shipped = 72 seconds

So for shipping to stay on task, their process must be capable of packing and loading one unit every 72 seconds. If they can’t consistently achieve that, they are falling behind.

What about the assembly lines?

You don’t know, because you don’t know what each of them is expected to produce. You could say that the factory takt is 72 seconds, but that does not pass the “so what?” test for the people working on those lines. But if you know that:

  • Line A’s leveled production is 75 units
  • Line B’s leveled production is 50 units
  • Line C’s leveled production is 100 units
  • Line D’s leveled production is 125 units

then you can determine a meaningful takt time for each of those lines.

  • Line A: 336 seconds
  • Line B: 504 seconds
  • Line C: 252 seconds
  • Lind D: 201 seconds

In reality, I am going to run these lines a little faster, but that is a different topic entirely.

Now we have a takt time that actually matters. It reflects the work cycle that must be achieved for that line to meet its obligation to its customers.

Example 2:

Upstream there are fabrication or other feeder processes. We have not yet gotten them into directly linked flow.

Process E feeds one part to each unit produced on Line B; and one part on every FIFTH unit on Line C. What is the takt time?

Line B needs 50 parts. Line C needs (100 / 5 =) 20 parts for a total of 70 units of output.

So Process I has a takt time of (420 minutes / 70 units of output =) 360 seconds.

Value stream mapping is very useful for untangling this. Hopefully you can also start to see one of the reasons we work so hard to level volume and mix.

This isn’t complex stuff, but on the other hand, if you oversimplify it then it becomes meaningless. Remember, this is not about OUTPUT, it is about testing whether your process has succeeded each and every time it is carried out. You can only do that if you know what is expected right then and there.

Go to your shop floor. Watch the work. Can you tell, with each unit of output, whether the team member was successful that time? (More precisely, can you tell whether you were successful in giving that team member what she needed to succeed!). If you can’t tell, I guarantee that the people doing the work have no idea, which means you are leaving them to guess. Not a good thing.

5 thoughts on “Takt Time Is Local

  1. Thanks for your post.

    How would you calculate takt time in situation where 5 products are ran through same machine with daily variation in exact ratio between products. One product is over 90% of volume daily.

    Also, if there is time available after all is ran for the day, the machine is used for 6th product for rest of the day.

    There is short changeover between when changing from product to another. And products come to workstation in batches.

    1. Panu –
      There is a takt time, but your situation is a little complicated to give you a concise reply.
      Remember that the point of takt time is to establish a target condition so that you can compare actual results vs. your target results and see the problems that are keeping you from hitting the target.

      You say “If there is time available…” which implies that this does not happen consistently. Why not? What causes the time to be available on some days but not on others? This might be a good starting point for further understanding of your process.

  2. Nice article. It reminds me of an email dialogue I had a few years ago with a gentleman from TMMK. Here is what he wrote (we were actually discussing feeder lines).

    “At Toyota, our Takt time is 55 seconds but to make an All Wheel Drive Rear Suspension it takes us 7 minutes, so we have a small, flexible feeder cell that builds at 7 minutes and feeds the main line at a rate of 1 AWD unit every 7 minutes. This is because our Heijunka calls for an AWD every 7 minutes.

    If we needed to make an AWD let’s say every 3 minutes then we would add additional manpower to our feeder cell to bring our cycle time down to 3 minutes.”

  3. Thanks for your response Mark. What follows is rather lengthy stream of thought.

    I am struggling a bit when calculating takt time for this machine due to mix of products we use it for.

    I know that I should use takt to give us picture of leveled customer need, but I can’t seem to be able to decide suitable available time to use. I know I shoudn’t mix output of machine with takt time calculations, but we can vary output by just adding people and that has great effect on time used and how much this machine can be used for other products during shift.

    Daily and shiftly mix variations cause the need to run this machine (and people working with it) with other products in addition to its main products.

    So we run this machine for products A-E as long we have them for that shift (there is no such option as leaving them to later shift). And then use remaining time to run products F or G.

    Would it be good idea to approach this with setting fixed amount of time used for F/G, like 2h per shift (and adjust when needed). And then calculate takt for main products using remaining time.

    Just to give you better picture, we are industrial laundry and machine in question is ironer used to iron pillow cases, napkins and table cloths and if there is time remaining then also sheets and duvet covers.

    If you are interested, one machine supplier has prepared following video describing modern laundry. My connection is breaking pretty bad currently and I can’t verify it right now, but if I remember correctly they have some shots of ironers as well.

    http://www.youtube.com/watch?v=OpiFp9i6owY

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