overlap. Many of the companies in the
supply chain for one are in the supply
chain for the other, and Clark had been
serving aerospace customers for more
than a decade at that point.
“In the aerospace industry, everything
is custom, everything is low-volume, and
everything has to be right,” TenBrink said.
Does this compound the challenges in
fabricating a tube that meets aerospace
requirements? Not necessarily. Every
fabricator has a story or three about an
original equipment manufacturer (OEM)
that uses dimensions or tolerances that
are simply impossible to meet, but engineers in the aerospace industry tend to
be savvy about such things.
“They understand tolerances, and
they tend to tolerance each dimension
appropriately,” he said. “They don’t use
a one-size-fits-all approach for every di-
mension on a drawing.”
So far, so good, but how does the
fabricator or the contractor verify the di-
mensions on a manufactured part? Many
measurement tools are available, but it’s
a matter of matching the tool to the ap-
For many manufactured products,
checking dimensions in a few criti-
cal areas is sufficient, especially when
evaluating sheet metal components with
flat or gently contoured surfaces. Some
auto body parts, such as hoods and trunk
lids, are good examples. When evalu-
ating a symmetric part with a few fea-
tures, checking a few key dimensions
often is the most efficient way to go, and
the evaluation is thorough enough
for the application.
A tubular assembly doesn’t usually
have consistency or symmetry along its
surfaces; it has straight lengths, simple
and compound bends, fittings, weldments, and radiuses rather than flats.
A check fixture is a conventional tool for verifying that a bent tube or tubular assembly
conforms to the print. A check fixture also can accommodate tools or equipment for drilling holes, trimming the ends, or in this case, orbital welding.