Strategos Lean Briefing

The Newsletter of Lean Manufacturing & Factory Science

April 22, 2003 www.strategosinc.com

All About Takt Time

Takt is a German word meaning musical beat, pulse or cycle. Its use in manufacturing dates to the 1930's when German engineers assisted Japanese aircraft manufacturers. They used the illustration of an orchestra conductor setting the beat for the arrival of each part or subassembly at just the right time (JIT). Takt time is the desired time between production units or output.

For simple workcells having a single product and a linear flow, Takt time is adequate for cell design. More complex cells have changeovers or variable routes within the cell. Here, Takt time is insufficient to establish the number of people required or the number of machines.

For these more complex workcells, we also need information on setup time, machine time, and person time. If the products vary significantly, we may need times for each product as well. This analysis is part of the second task in workcell design, "Engineering The Process".

Takt time and One Piece Flow are valuable concepts, but a narrow focus on them can have negative consequences. For example, if workcell designers sense that these concepts are inadequate for a given product-process mix, they may give up on the use of workcells.

Far more dangerous is the situation where designers proceed on blind faith and apply Takt time and One Piece Flow to a mix that is unsuitable. Our web page "When Blitzing Replaces Strategy" illustrates.

Workcell design is an engineering challenge requiring knowledge of several scientific disciplines. It is not an activity suited to exhortations, blind faith and simplistic slogans.

I have been designing cells since the late '70s when I helped with the early computerization of of Group Technology. I also conducted seminars on Systematic Layout Planning. This, plus experience with clients, culminated in the structured layout and workcell design approaches in my two books on facility planning.

A significant part of our website addresses these issues. A good place to start exploring is at our page "How To Design Workcells".

Our next issue addresses Manufacturing Strategy with a classic case study first published by Wickham Skinner. See you then.

Quarterman Lee

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