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.
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.
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 process.
Bob Sproull
Bob Sproull
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Not a problem....go ahead and share it.
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