![Lean Briefs Logo](images/logos/briefs1.gif) 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
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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