I am a member of over 50 groups on LinkedIn, a very popular social media site,
and although I enjoy all of them, one group in particular, named TLS, is my
favorite. Not because it’s all about the
integration of the Theory of Constraints, Lean and Six Sigma, which I write
about often. It’s because most of the
discussions are so animated and full of passion between the group members. There have been discussions about things like
whether the TOC community should consider renaming the Theory of Constraints to something much less academic or less
daunting to people unfamiliar with it.
There have even been discussions about what the actual definition of a
constraint really is. And while I have participated
in some of these discussions when I have time, for the most part I just lie in
the shadows and follow the on-going dialogue about the subject at hand.
Not long ago there was a rather animated exchange
about Constraints Management, but rather than participating in this discussion,
it was one of the ones that I chose to just follow and absorb the dialogue.
Since then, I’ve had some time to give this subject a bit more thought and
decided that rather than posting my thoughts on the LinkedIn site, I’ll do it
here on my blog. I hope this isn’t a wearisome and tedious series for all of my
loyal readers.
Let me start by saying that Constraints
Management (CM) is really a product of the Theory of Constraints which Eli
Goldratt and Jeff Cox introduced to the world in their early 1980’s
breakthrough book, The Goal. Some of the ideas presented in that first
edition weren’t so novel, but most were and were truly innovative. Goldratt and Cox weaved together principles, tools
and techniques in a fictitious
manufacturing plant and did so in a business novel format that captivated and
fascinated the early readers and still does so today. Plant managers from all over the world
identified with Alex Rogo, the fictional plant manager in the book, and many
said, “Hey, that’s me they’re talking about!”
From this first book, Goldratt went on to write a sequel to The Goal named It’s Not Luck and introduced new principles, tools and techniques
all under the umbrella of the Theory of Constraints.
Schragenheim and Dettmer, in their classic
book, Manufacturing at Warp Speed
(St. Lucie Press, Boca Raton, FL, 2000, Ch. 2) told us that Constraints
Management is based upon four basic assumptions relative to how a system
functions.
2. “The sum of the system’s local optima does
not equal the global system optimum.” What
this means to me is that the most effective system doesn’t evolve from
optimizing the efficiency of each individual part of the system, but rather we
must consider all interactions within the system. In other words, if you are a company that uses
efficiency as a primary metric, for example, maximizing the efficiency of each
part of the system won’t guarantee maximum system effectiveness.
3. “Very few variables – maybe only one – limit
the performance of a system at any one time.”
When Goldratt and Cox introduced the concept of a constraint, they
likened it to a chain which has a weakest link.
Like the chain with a weakest link, systems also have a weakest link
that must be identified and exploited before the system will improve.
4. “All systems are subject to logical
cause-and-effect.” In any system, there are
negative symptoms of problems, termed Undesirable Effects (UDE’s, pronounced
oodees), that exist within the system. These
UDE’s are linked together in a logical hierarchy of cause-and-effect with the
core problem located at or near the bottom of the linkage. In Constraints Management it is believed that
these by solving the core problem, approximately 80 % of these UDE’s will
disappear from the system.
These four assumptions form the basis of
Constraints Management for me, but what are their implications from a
continuous improvement perspective? In my next posting we'll
look at each of these four assumptions in a bit more detail.
Bob Sproull
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