Thermo101 Downgauging

A TECHNICAL ARTICLE 2007 VOLUME 26, #2

“Down Gauging” – It’s a Good Thing

How many of us quote jobs and
specify the starting gauge? I would
suggest that the majority of custom
thermoformers are accustomed to quoting
this way. In the case of proprietary
thermoformers producing such things
as food service items, although the
starting gauge is a major factor in the
costing of the parts, it is of little interest
to the customer because he or she only
cares about how well the part performs
which would relate only to the thickness
of the finished part. So why do custom
thermoformers continue to state starting
gauge on their proposals?

My point is this. Why should any
customer buying thermoformed parts,
care about what gauge of raw material
we start with. He should only care about
how well his part performs. We sell to a
wide variety of customers, from the very
knowledgeable to the –well lets be kind
and say, technically challenged. With
the latter we have a duty to explain the
process of thermoforming and how the
plastic thins during heating and forming.
Those who already understand may
need to be reminded and shown where
the thinning will be most prevalent.
In all cases however, we must educate
our customers and work with them
to determine what the minimum wall
thickness should be and in some cases
specify the thickness in various places on
the part. Once he or she has established
these thickness criteria, it should become
the specification with no mention of the
starting gauge.

Unless we are dealing with a seasoned
customer who has already considered
wall thickness requirements, most of the
time customers will indicate the need
for a specific starting gauge. This may
be because he or she has a competitive
proposal that specifies a starting gauge or
the part is existing and because the spec
calls for a starting gauge he or she simply
assumes that it should continue to be that
gauge. If we are not given a material
gauge requirement in the RFQ, many of
us will be unsure what gauge should be
used so we will quote 2 or more. Would
it not be more professional to do some
homework and quote the part stating a
minimum thickness or perhaps even a
range of wall thickness measurements
throughout the part?

When I bring up this point with those
in the industry I am told that the “good”
thermoformers do not quote starting
gauge. This leads me to believe that what
separates the “good” thermoformers
from the “not so good” is know-how.
That is, knowing how to produce the
part with the specified minimum wall
thickness requirements using the thinnest
possible starting gauge. What do we
need to know to be able to produce the
part with minimum wall thickness specs
and do so with a thinner material than
our competition? Are the lights going
on yet?

Dare I say that, “down gauging”
has some negative connotations that
relate to using a material gauge that
is less than what was quoted because
the term “down gauging” is sometimes
used when competitive pressures force
a need to reduce costs. However if
starting gauge is never specified, then
we would eliminate any possibility of
being accused of such a practice. It is
a win – win situation for supplier and
customer. The real competitive edge
goes to the thermoforming supplier with
the most know-how and there-in lies the
moral of the story.

We in the SPE are trying to educate
thermoformers to be more competitive,
more innovative and more successful.
Those who work to that end will
ultimately prevail. Having the know-
how to be able to guarantee a minimum
wall thickness with a thinner starting
gauge is indeed, a superior way to sell.
By using better material, better part
design, better tooling or better equipment
than our competition, we will get the
job and have a much better chance of
keeping the job if it gets shopped around
by the customer.

One way to produce a thermoformed
part in a thinner gauge, while still
maintaining a minimum wall thickness is
to look at some of the different forming
techniques available to us. Many of
us have listened to seminars by Bill
McConnell or Art Buckel that show
techniques such as billow forming or
snap-back forming. These methods are
designed primarily to provide better
material distribution which of course
relates to improved wall thickness in the
critical areas on the part. Of course in
order to utilize these techniques we must
build special tooling, have the equipment
that allows the extra step in the process
and we may have to extend the cycle
time a little. However it could result
in getting the job because of a more
uniform part, a significant reduction
in starting gauge and consequently a
reduction in material costs.

It is one thing to know what techniques
and tooling will improve material
distribution and another to predict wall
thickness accurately. An experienced
tool designer who has the benefit of
many years in the job will be able to do
so fairly well; however, these people are
scarce. There are computer simulation
programs available that can assist with
this and make the predictions within
a few thousandths of an inch. One of
these programs could become your best
sales tool.

Like most practices that have
become routine, modifying our quoting
procedures to reflect minimum wall
thickness instead of starting gauge will
take some effort. It will require us to take
more time with the customer to agree on
the specs. It will require knowledgeable
engineering personnel to determine tool
design, process techniques and what
gauge material to use. But in my opinion
it will make us better thermoformers
by putting the responsibility on our
engineers to find ways to down gauge
while maintaining wall thickness
requirements. ¦

THERMOFORMING

101

(Technical Editor’s Note: Thermoforming 101
articles are intended not only to educate but also
to generate interest in making improvements
in our industry and our businesses. I welcome
any feedback, positive, negative or otherwise.
If I have provoked some dialogue and thought
by writing an article like this it is for the good of
the industry.)

Leave a Reply