By Eric Lundin, Editor
Although the U.S. steel industry isn’t as largeasitusedtobe, itstillpacksapunch. In 2012 U.S. steel companies produced
88. 6 million tons of raw steel, which made the U.S.
the third-largest raw steel producer in the world.
;e industry was larger and growing in 1965, with
an output of 119 million tons, when Edward Kress
founded Slagaway Corp. Kress’ idea was to design
and build vehicles to lift, haul, and pour out slag
pots, the enormous containers used in the basic
oxygen furnace (BOF) steelmaking process.
It was a big ambition, but Kress was up to it. ;e
Kress family had been involved in manufacturing
transportation machinery for three generations.
Kress Brothers Carriage Co. manufactured motorized fire trucks in the early decades of the 20th
century, and Kress’ father Ralph had designed o;-road haulers for the Dart Truck Co., Caterpillar, and
LeTourneau.
Edward Kress initially focused on slag pot carriers. He later broadened the company’s product
o;erings (and renamed it Kress Corp.), branching
out to design and manufacture other specialized
vehicles for moving steel slabs, lifting stacking steel
coils, hauling and dumping coal, and unloading
railcars. It even manufactures specialized personnel carriers for researchers in Antarctica.
Despite the variety of machinery, Kress products have one thing in common: ;ey are enormous. ;e payloads range from 600 to 400 tons
and the engines develop from 400 to 2, 100 horsepower. ;e cold-weather personnel carrier holds 60
people. ;e thickest components are made from
6-in.-thick plate. A single tire can cost as much as
$40,000. In most cases, the driver climbs a ladder to
enter the cab.
In an environment where everything is on a big
scale, it’s understandable that small components
would get short shrift. Indeed, for years the com-
pany’s hydraulic lines, cab ladders, and handrails
were bent on a manual bender. Only recently did
the company upgrade to a CNC tube bender.
Protractor, Level, and Intuition
;e old manual bender left a lot to be desired. It
held just one bending die and had no additional
features. ;e bending sta; had to use a manual
protractor, fastened to the tube with locking pliers,
to measure the rotation of every bend. To make a
second bend in a di;erent plane, they used a common bubble level to ensure the first bend was level
before making the second bend. Getting it right
was a slow, deliberate process, considering that
some of the parts are 20 ft. long and contain up to
10 bends in several planes (see Figure 1).
It was hard to get it right every time. Compensating for springback was largely a matter of intuition, but tube can vary quite a bit from heat to
heat, so even years of experience didn’t eliminate
inconsistencies. Kress compensated by checking all
of the tubular components on a coordinate measuring machine (CMM), but this added to the time
needed to fill service orders and tied up the CMM
quite a bit. It also revealed just how di;cult accurate bending can be.
Seeing the Difference With CNC
;e company’s decision to purchase a CNC tube
bender resulted in a quantum leap in productivity.
Comparing its new machine, a YLM model 50S2
ROSM-4A from J&S Machine, to its old machine
is like, well, comparing a subcompact car to Kress’
cold-weather personnel carrier. Both can move
passengers from point A to point B, but beyond
that, there is no comparison.
;e bending sta; uses the machine’s interface to
pull up the part drawing, or imports the drawing
if it’s a new part. ;e next step is a simulation that
shows how the tube will feed into the machine, and
how the machine will bend it. ;is routine tracks
the entire length of the tube, making sure that the
end of the tube doesn’t crash into the bender (see
Figure 2).
After loading the tube and ensuring the work
area is clear, the bender operator initiates the bending sequence, and the machine proceeds to form
the tube. After that’s done, he unloads the bender
and loads the next tube.
;is is a huge improvement over the old process.
Then: After looking over the work order and
pulling the corresponding part print, the operator
would pore over the blueprint; figure out the bending sequence; then start the painstaking process of
loading, clamping, bending, measuring, repositioning, leveling, bending, measuring, and so on.
Now: For a new part, the operator uses the
bender’s software to import the CAD drawing;
Better bending cuts production time, improves
consistency for heavy equipment manufacturer
Figure 1
Bending a single hydraulic tube is one thing (inset); assembling a hydraulic system is something else altogether. A little
bend variance in one tube might be acceptable, but if every tube is plagued with some amount of inaccuracy, plumbing the system becomes increasingly di;cult.
