ly everything in the first few mills,” said
Executive Manager Rob Adams. It’s almost baffling that a sole engineer would
take on such a task without substantial
resources—a corporation staffed with an
engineering and design team to attend
to the myriad details, a fleet of machine
tools and experienced operators to make
the components, and the deep pockets
to buy the raw materials and pay the salaries for such a venture—but on the other hand, this path makes a lot of sense.
Gilreath knew what it took to make a
high-quality tube, so why not go it alone
and develop proprietary equipment and
tooling to support his vision?
DIY Tube Mills
Gilreath’s approach makes sense: Make
good tooling, mount it to high-quality
shafts that rotate on the best bearings
money can buy, use a proprietary drive-train, enclose it all in a sturdy housing,
and you’re well on your way to developing stable, repeatable processes, which
is the key to making quality tube.
A key feature concerns roll tooling
adjustment. Gilreath developed a system
that uses adjustment knobs. When a mill
operator needs to make a slight adjustment in a tool’s position, he can give a
knob an eighth of a turn. That sounds like
a fine adjustment, but at 22. 5 degrees of
rotation, it’s a coarse adjustment. If an
eighth of a turn was too much, no problem. He can back it off by a sixteenth of
a turn, and maybe another thirty-second
of a turn after that, if necessary, which
is 5.625 degrees of rotation. A tube mill
with infinitely variable adjustments on
the tooling gives new meaning to the
phrase fine tuning.
The last piece of this formerly mystifying puzzle is Gilreath’s perspective
on the tooling itself, specifically tooling
quality, which leads to G & L’s view of
“In Gilreath’s view, the tolerance of
any tooling dimension is plus or minus
zero,” Adams said. He wasn’t kidding.
While no company guarantees that its
products meet such an exacting stan-
dard, G & L gets close. Its website cites
a tolerance of ± 0.002 inch for
many of its products.
A Tale of Tooling. Striving to make
tooling to an exact size with no tolerance is one of three overlapping factors
that illustrates the role that tooling has
at G & L. Second is the array of tooling.
“Nearly every set of tooling in the
tool crib matches a product’s OD and
wall thickness,” said Director of Sales
Bill Henricks. “This is because, for a
given OD, the strip width changes as the
wall thickness changes, so the ideal edge
guide changes, too.” This isn’t to say that
all tube producers need such exacting
standards for all products, but it shows G
& L’s focus on precision.
The third factor is the depth of experience of G & L’s tool- and diemakers. The
tooling staff’s turnover rate is, well, essentially zero (plus or minus zero).
“Two have more than 30 years of experience,” Adams said. “The manager
is a degreed engineer from Tennessee
Tech,” so the tooling department staff is
fortified by both experience and education. It would be almost impossible to
hire a qualified tool-and diemaker, so
the company relies on in-house training.
Steel and Beyond. A key attribute at
G & L is a thorough understanding of
metallurgy. While Gilreath had a deep
understanding of steels of all sorts, his
knowledge of metals wasn’t limited to
steels. Around the time that Gilreath was
thinking about establishing G & L, titanium was transitioning from a niche metal
to the mainstream.
Titanium’s combination of high
strength, light weight, and excellent
corrosion resistance makes it ideal for
aeronautical and space applications and
contributed to many of the advancements in aeronautics in the 1960s and
1970s—and it still has a primary role in
aircraft and spacecraft. For decades it
was so expensive that few industries outside of aerospace used it, but by the late
1970s its price had dropped enough to
make it a viable material for more applications. Gilreath saw the potential in
titanium early on.
“Titanium is available in more than
sixteen grades,” Henricks said. “The majority of titanium tubing used in aerospace application is seamless,” he said,
but welded titanium tube has many
G & L makes tubing products in many shapes for many applications. Rounds, rectangulars,
and flat ovals are the most common. The main applications are fluid delivery and heat
transfer. As such, the products must resist corrosion from many aggressive chemicals, withstand extreme temperature cycling, and endure severe forming operatins.