69
Chapter 7
SMED (Single Minute
Exchange of Die)
Introduction
SMED stands for single minute exchange of die. The SMED concept was
developed by Japanese industrial engineer Shinego Shingo while working
with Toyota in the 1960s. Shingo saw that Toyotas biggest bottleneck was
the time it took to change the dies on the large transfer-stamping machines
that produced car body panels. The dies were extremely large and heavy,
and replacing one took an inordinate amount of time—12 hours or more. So,
each die change was a major event and, from a practical standpoint, neces-
sitated long production runs because the time and expense of die changes
made short runs uneconomical. This translates into big inventories, more
costs, and very large consequences of error.
So, what does this have to do with manufacturers not in the auto indus-
try? The answer is plenty—unless you only make one product in one color
on each of your production lines. However, if you make more than one
product on a production line, applying the SMED principles should save you
a lot of time and money and reduce variability, which is the main thing.
The Vision
Were the Japanese ever able to reduce the amount of time to perform an
automotive die change from half a day or more to one minute? No. But, they
reportedly got it down to 10 minutes. They were able to do that because
they had a vision: one minute. You will need to make the same kind of
70 ◾  Removing the Barriers to Efficient Manufacturing
assessment of your operation. The main question is what it is costing you in
time, labor, materials, waste, and inventory size to make a product change-
over. And, after the changeover, how long does it take after startup to be
making first-class quality product again?
Just like the Japanese, you will also need a vision. So, here is one based
on Point 9 of our Model Vision. The ideal changeover would be instanta-
neous: You push a button, and one minute later, instead of making one
product, you are now making a different product. And, the new product is
immediately good quality. Since this is a common dream among manufac-
turers, they invented a new term: one touch exchange of die (OTED). The
vision for changeover under OTED is 100 seconds or less. If this is not a real-
istic vision for your facility, you will need to develop one that is—aim high.
Getting Started
In the context of producing multiple products on a single production line,
there are some steps associated with a changeover that would appear to be
universal and somewhat self-evident:
1. After shutting down for a changeover, the process must be rendered
safe for people to enter and work on it.
2. The process should be cleaned.
3. Machine settings have to be changed.
4. Some components of the process may have to be replaced (just like the
stamping dies).
5. Some raw materials and operating supplies have to be replaced.
6. After initial startup, additional product sampling is needed to ensure the
transition is successful.
7. Machine settings may have to be tweaked before process centerlines
are attained.
We analyze each of these in detail.
Step 1: Render the Process Safe
While you would like for your employees to be able to function with the
efficiency of a NASCAR pit crew, they have to be able to perform their tasks

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