This
past week I was asked a question about how I present the basics of the Theory of
Constraints to people not familiar with its teachings. Or more specifically, how do I teach my
students or improvement teams about how to understand the basic concept of
constraints. So in the next two
postings I’m going to share with you a series of slides on how I present this
basic concept. For those of you who are familiar with my blog, this is a repeat posting for a couple of years ago with some slight changes.

The
best way I have found to help people understand just what a constraint is and
how it impacts the flow or throughput through a process is by using a simple
piping system diagram with each pipe having a different
diameter. As you read this posting, remember what we are trying to demonstrate is the concept of flow and how the constraint controls it.

In
this first slide I simply explain that this is a drawing of a cross section of
pipes used to transport water through each section of pipe and into a collection
receptacle at the bottom. I then tell them that we need more water flowing and
that they have been chosen to fix this system. I emphasize that this system is fed via
gravity, so they can’t simply increase the water pressure.

In
my next slide, I pose the question that if enough water isn’t flowing through
this system, what must they do to make more water flow? Someone in the group will automatically state
that in order to have more water flowing through the system, we have to increase
the diameter of Section E.

I
ask everyone if they understand why they must increase Section E’s diameter and
most will answer that they do. For
anyone who doesn’t, I simply explain that because of the constricted nature of
Section E, water flow is limited at this point. Since they all now have an
understanding of this basic concept, I then move to the next
slide.

This
slide reinforces what I just explained, but then I ask another important
question about how large the new diameter should be. In other words, what would this depend
upon? What this is supposed to
demonstrate is that demand requirements play a role in determining the level of
improvement needed to satisfy demand requirements.

In
the next slide, I demonstrate the new diameter of Section E and how water is now
flowing at a much faster rate than before the diameter change. The important point I emphasize is that the
system constraint controls the throughput of water through every section of pipe
and if we don't subordinate the rest of the system to the same throughput rate
as the constraint, we will automatically have a WIP build-up in front of the
constraint.

I
then ask the class to identify other physical changes to this system have
occurred as a result of our exploitation of the constraint (i.e. increasing the
diameter of Section E).

I
give them time to answer this question, and most of the time the group will
answer correctly. I then post the next
slide to reinforce that changes to the system.

I
point out that, first and foremost, the system constraint has moved from Section
E to Section B. I next explain that the new throughput of water is now governed
by the rate that Section B will permit. And finally, I point to the queue of water
stacked-up in front of Section B. I now
make the point that if the amount of water is still not enough, then we must
decide how to exploit the new system constraint and that the process of on-going
improvement is continuous.

In
my next slide I ask the question, “Would increasing the diameter of any or all
other sections have resulted in any more throughput of water through this
system?” This question is intended to
demonstrate that since the system constraint controls the throughput of a
system, focusing improvement anywhere else in the system is usually wasted
effort. What I finish with is a before
and after slide just to reinforce how things have changed by focusing on the
constraint.

In
my next posting, I'll present the rest of my training package moving from the
abstract piping system to the real world.....a real process.

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