Jul 5 2012
Yet another (wrong) definition of takt time
This is from a blog post published today that claims to clarify what a takt time is:
Takt Time: This is the rate of time at which a product or service is being purchased. For example, a Nissan commercial mentioned that every minute, someone in the world buys a new Nissan. Selling a car every minute is an excellent example of takt time!
Writing a definition for a thing or an idea is tricky. Following Aristotle, I would say that you have done a good job if you have described what kind of a thing it is and how it differs from other things of the same kind, using terms your reader already understands.
In this definition, takt time is described as a “rate of time.” If there were such a thing as a rate of time, in what units would it be expressed? In production, a rate is expressed, for example, in pieces per hour; a time, in minutes or seconds. Takt Time, as its name suggests is a time, not a rate, and certainly not a rate of time, whatever that may be.
This definition then relates takt time exclusively to “a product or service [..] being purchased,” and gives the example of a Nissan being bought every minute in the world, suggesting that 1 minute is the takt time of a Nissan. Incidentally, if this figure were true, Nissan would sell about 500,000 cars/year, versus the 4 million it actually sells.
Takt time, as we use it in manufacturing and industrial engineering, is in fact not a parameter associated with just a product but with a production line making this product. Given the demand that is given to it and the amount of time that it actually works, the takt time of this production line for this product is the time that must elapse between two consecutive unit completions.
If a line is expected to produce 400 units of a product in a 400-minute shift, then, if you stand by the last station of the line, you will see one unit come out every minute, meaning that its takt time is 1 minute. If you switch from working 1 shift/day to 2 to meet the same demand, you double the takt time to 2 minutes.
This is why it is calculated as follows:
It has a numerator and a denominator, and both matter. They are obviously calculated for the same time period.
Jul 5 2012
Amazon.com: Michel Baudin’s review of Gemba Kaizen, 2nd Edition
See on Scoop.it – lean manufacturing

Includes good case studies, but oversells Kaizen (*** rating on Amazon)
Masaaki Imai is the grand old man who brought the words Kaizen and Gemba into the English language. I did, at some point, work for his company, and was exposed to his ideas then.
Gemba Kaizen has two parts. The first half is a general theory; the second, a series of case studies. Imai’s perspective is that Kaizen is the umbrella concept encompassing all efforts to improve not just factories but all businesses. In his view, TQC/TQM, the Toyota Production System, TPM, Hoshin planning, suggestion systems and small-group activities are all “Kaizen Systems.” It is understandable on Imai’s part, because he first made his mark with a book called Kaizen in the 1980s and called his consulting firm the “Kaizen Institute.”
It is, however, a stretch to make Lean or the Toyota Production System just a “Kaizen System.” Instead, Kaizen is part of what you need to do to implement Lean, but you could not achieve Lean with just Kaizen. Kaizen is continuous, incremental improvements made by those who do the work, and is as necessary as Imai says it is, but it is by no means sufficient, as Lean requires radical changes as well.
The theoretical part contains some valuable information but also overenthusiastic statements such as that the Gemba is the only source of information. Just because the Gemba is too often ignored doesn’t mean that the company’s information systems are useless. They also contain valuable information about customer orders, product configurations, or production history that cannot be inferred just by observing the shop floor.
As is common,the case studies are the most informative part of the book, but they do not necessarily support the premise that the Kaizen concept is central to all improvement. For example, the Production Preparation Process (3P) that is the subject of one of the cases has nothing to do with Kaizen. Some of the stories are also incomplete. The Wiremold case is described through an interview with former CEO Art Byrne, ending with the acquisition of the company by Legrand in 2000. While the post-acquisition epilogue doesn’t make the case for Kaizen, the reader might be interested to know that the new owners sank the company in the following years by reversing what Art Byrne and his team had done.
In conclusion, while I disagree with many of Imai’s ideas, I like to know what they are, and this book serves this purpose.
See on www.amazon.com
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By Michel Baudin • Book reviews 2 • Tags: Kaizen, Lean