Confused about Time

Time ConfusionFor those new to continuous improvement the concept of time can be confusing. In this article I hope to clear up some common misunderstandings.

Takt Time

The word takt comes to us from the German language and literally means pace or rhythm. It’s also a term often associated with the takt a conductor sets so that the orchestra plays in unison.

We often speak about takt time as being the pulse or the heart beat of a lean production system. In other words, takt time is used to match the pace of work to the average pace of customer demand.

You must calculate takt time.

Cycle Time

Cycle time describes the total time it takes an operator to complete one cycle of an operation, including any walking, inspection, etc. We typically measure cycle time with a stop watch.

Value Creating Time

The value creating time (VCT) is similar to cycle time, with one exception. With VCT we are only interested in the time the product is actually being transformed.

In other words, we subtract any non value added time (muda) from our cycle time in order to get to our value creating time.

Total Cycle time / Production Lead Time

We are speaking about the total cycle time, or production lead time, when describing the time is takes one unit to move through the entire value stream.

An easy way to picture this is to imagine marking your initials on some raw material at the beginning of the process and watching how long it takes to make it through to the end.  You should really try this… it may surprise you how long you wait!

Summary

As you can see, there is quite a bit to this time concept.  Depending on which book you read or expert you talk to, you may hear slightly different names than those above. 

The key is to remember that different aspects of time exist as it relates to continuous improvement… but as long as you are consistent in your naming convention all should be well.

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3 Comments

  1. Timothy Simmons

    May 1, 2008 - 9:00 pm

    I have often been confused about cycle time. When you read books like Learning to See they make it seem like cycle time is always value added since you use it in the VA portion of the PCE formula. When in fact this is really not accurate since there is waste within cycle time. So the better PCE formula would be to use the ratio of Value Creating Time to Non Value Adding time, right?

  2. Ron Pereira

    May 2, 2008 - 9:25 pm

    Great question. Typically, we note the overall CT in the VSM timeline. With this said, I don’t see any reason you couldn’t use the VCT instead. You could also report both.

    Don’t let the “books” fool you into thinking there is just one way to use these tools. Use your imagination and try things out. That’s how true breakthrough improvement happens.