Page 267 - How To Implement Lean Manufacturing

Using the Pr escription—Thr ee Case Studies 245

Very often, to those seeking weight loss, they put all their faith in the diet and plan
to do nothing more than “stick to the diet.” Their hope is that in the diet, and in the diet
alone, they will reach their goal of permanent weight loss and improved health. If the
dieter has the ability to stick to the diet, the results are predictable. Lots of early weight
loss. That’s not too difficult, but can they sustain the weight loss and improve their
health as well? That usually depends on what else they have done. Have they changed
their sleeping habits? Have they changed their exercise habits? If the diet is all they did,
with certainty the weigh will come back and with that ugly weight will come the emo-
tional baggage of failure and guilt.
In this light, many managers view value stream mapping like the latest diet craze.
They hope VSM is the “key” to their success and they think they need to do nothing
more to analyze their situation than prepare a few value steam maps, from which they
can fully analyze and fully improve their plant. If that is the only analytical tool they
use, and they rely on it alone, the results, just like the dieters, are predictable. There will
be short-term gains, encouraging gains, but again like the dieter’s situation, over time
these gains will likely regress and with this will come the emotional baggage of dissat-
isfaction and disillusionment.
In fact, putting all your eggs in the diet basket, or in the VSM basket, is just another
version of the “silver bullet’ or the “quick fix” mentality—and history has shown time
and again it simply does not work in any field of endeavor.

Should We Ignore Value Stream Mapping?
So does that mean we should ignore value stream mapping? Of course not—no more
than the dieter should ignore the diet. Value stream mapping is a powerful tool that
allows you to see the production operation from a different perspective, and a powerful
perspective—from a distance. It allows you to see how the various parts of the value
stream are connected and how these pieces add up; how they increase the lead time and
increase the waste accumulation in the value stream. Its major advantages are twofold.
First, it focuses your attention on the total value stream and assists you in avoiding the
problem of point optimization at the expense of system optimization. Second, it is the
most direct and powerful way I have seen to focus on lead time, the key metric of
whether a facility is truly Lean.
But just what are its shortcomings as an analytical tool? Value steam mapping is a
“macro tool” in that it has an overview aspect and does not get into many of the details
that must be understood if you want to make your plant Lean. The biggest weakness is
in analyzing cell performance. Cell performance is absolutely crucial to overall perfor-
mance. So we need other tools to analyze cell performance, and if we do not properly
analyze the cell performance, we will end up with good connections between cells that
are performing poorly.
I find it is best to prioritize your improvement efforts, inside-out, so to speak. First,
start at the cell, make it efficient and effective. Once this is done, connect the cells—this
is where the VSM is powerful. There is nothing wrong with improving the cells and
improving the cell-to-cell flow, simultaneously. But it is simply incorrect to ignore the cell
performance and it is highly inefficient to do it after the value stream mapping effort.
Although that sounds trivial, it is missed by many and with the power of a value
stream map driving a project, a lot of progress will be made. In short order, however,
the poor performance of the cells will create problems, and these issues will need to be
addressed. In the end, the macro work uncovered by the VSM will often need to be
redone.