Carbon-Fiber Tooling - Bilsing Automation

Hydroformer
Benefits from
Schuler Inc., Canton, MI, not only
offers innovative metalforming
systems and technology, but also
performs production hydroforming.
The firm supplies hydroformed components
used in an array of applications,
including automotive, heavy
truck, ATVs, motorcycles, appliances
and office furniture. Part size ranges
from tubes 1- to 6-in. dia. with wall
thickness from 1.4 to 8 mm.
Initially established as a hydroforming-technology
proving ground,
the Canton facility has evolved to take
on full commercial hydroforming pro-
Carbon-
Fiber
Tooling
Carbon-fiber end-of-arm
tooling on press-tending
robots results in a 6-sec.
reduction in cycle time
when hydroforming
engine-cradle
components, while
elevating part consistency
and process repeatability.
High-payload robots tend to the Schuler
hydroforming operation. Because robot
performance depends on the weight (and
weight distribution) being cantilevered,
the use of carbon-fiber material leads to
increased speeds and quicker settling
times within the working envelope of the
robots, promising throughput gains.
24 MetalForming/June 2011 www.metalformingmagazine.com

duction. It operates a press line comprising
a Schuler 500-ton hydraulic
preform press and an 8500-ton hydroforming
press. The line is tended by
five high-payload robots—model
KR150 robots from Kuka Robotics
Corp., Clinton Township, MI. The
robots are particularly well-suited for
transfer and load/unload tasks, allowing
Schuler to support the design and
manufacture of prototypes as well as
high-volume production.
Discovery of Carbon-Fiber
End Effectors
Prior to 2005, all of the robots’ endof-arm
tooling used at Schuler for part
handling was constructed by outside
suppliers. This approach proved costly
and still resulted in some reconfiguration
and tuning at die tryout, according
to Schuler plant manager Craig
Zeleji. The firm then decided to try its
hand at building end-effector tooling
inhouse. It developed a design based on
readily available, interchangeable components
using standard 2.5-in.-dia.
tubular aluminum for the main boom.
Extension arms, designed to hold
clamps and magnetic grippers, were
fabricated from 1-in.-dia. aluminum
tube.
While attending an industry tradeshow
in 2006, Zeleji spied an alternative
tooling solution: carbon-fiber tooling
(from German supplier Bilsing Automation,
also in Clinton Township, MI).
The tooling was designed to replace
traditional aluminum products. What
piqued Zeleji’s interest was the potential
benefits associated with tooling
constructed from high-modulus, lightweight
graphite carbon fiber.
Zeleji set out to evaluate the carbon-fiber
tooling on a Chrysler production-hydroformed
component for
an engine cradle, weighing about 20
lb. At the time, the baseline tooling
being used in production at Schuler
was constructed of aluminum, with a
rotation device mounted on the leading
edge of the end effector. The tool handled
two blanks—it picked and placed
one blank for cleaning and lubrication,
and placed a second blank, following
lubrication, into the die cavity.
A Heavy Load
Schuler designed the process with a
two-cavity die, although the robot
could only load one component at a
time due to the combined weight of
the parts and the end effector. The
weight of the tooling limited robot efficiency
and made tool changes cumbersome.
Further, the weld joint at the
end-effector pivot point became susceptible
to cracks.
Says Zeleji: “The challenge was to
more efficiently manufacture these
types of parts, since we were running at
below rated press capacity for stroke
rate, because the robot could only handle
one part at a time.”
Carbon-fiber tooling addressed
these problems by providing a lighter,
stiffer alternative. Because robot performance
depends on the weight (and
weight distribution) being cantilevered,
the use of carbon-fiber material leads
to increased speeds and quicker settling
times within the working envelope
of the robots, promising throughput
gains.
The Carbon-Fiber
Value Proposition
When Zeleji began working with
Bilsing, Schuler already had designed
the tooling for a complete solution,
from the part back to the robot’s wrist.
Conforming to standard interchangeable
sizes, Bilsing’s carbon fiber was
relatively simple to integrate into the
end effectors.
Says Zeleji: “Since the carbon fiber is
interchangeable with the aluminum,
it was used as a direct replacement.
This allowed us to immediately begin
ramping up for production.”
Use of carbon fiber not only allowed
the engineers to manufacture tooling in
the same diameters, but it offered significant
strength and stiffness advantages
over aluminum. To achieve the
same strength of carbon fiber, Schuler
would have had to double the wall
thickness of the aluminum tubing—
Common Misconceptions
Work remains in order to convince more metalformers to consider
use of carbon-fiber tooling, according to Ben Pauzus, general
manager of Bilsing Automation North America. “We can dispel
some of the common myths associated with carbon fiber if
companies would take a look at the benefits to be gained,” says
Pauzus. “Although carbon-fiber tubing is more expensive than
aluminum, in the overall scheme of production tooling, the endof-arm
framework comprises just a fraction of the overall cost
when you include the pricetag for the grippers, magnets, clamps,
etc. Therefore, the premium paid for the carbon-fiber framework
is easily offset by its light weight and stiffness, and the potential
gains in productivity.”
Generally speaking, carbon-fiber components weigh half (or
less) than do comparable aluminum parts. Carbon-fiber tools
also exhibit good toughness and wear resistance, and can be
used in applications where high heat and hot flash are issues.
Contrary to popular belief, today’s high-modulus carbon fiber
offers increased strength and rigidity without being brittle. This
makes the material easy to manipulate and simple to integrate
into tooling.
How does this benefit press-tending applications Consider,
for example, a recent Bilsing customer that had designed a large
steel end effector required to carry a 2700-lb. load. The frame
itself weighed more than 615 lb. Altogether, the weight of the
part, end effector and tooling exceeded the capacity of the
robot. A redesign of the end effector using carbon fiber reduced
the weight of the end effector by 500 lb., resulting in a 114-lb.
tool and bringing the total weight within the robot’s capacity
limitations.
Additionally, carbon fiber can help to extend the service life of
robots simply due to the harmonics. Carbon fiber absorbs vibration
rather than transferring it to the robot, where it wears on joints and
other components. Carbon-fiber tools also cease to bounce or
shake almost immediately after settling into position, reducing or
eliminating the need for clamping devices used to prevent bounce
and shake associated with aluminum end effectors.
www.metalformingmagazine.com MetalForming/June 2011 25

Carbon-Fiber Tooling
and still would not realize the high
stiffness properties of carbon fiber.
According to Zeleji, “because carbon
fiber made the overall tooling so
much lighter, we were able to handle
additional part weight, achieving a 10-
to 15-percent increase in production
weight. We also realized a 6-sec. reduction
in cycle time, representing an overall
productivity gain of 15 percent. And,
part consistency and process repeatability
improved because the new tooling
proves to be more harmonically
stable—there is less bounce.”
The Ergonomic Advantage
Further process improvements
included increased ergonomics, noted
particularly when it comes time to
change tools. Says Zeleji: “We don’t
have automated tool change capability,
so it was important to make it easier
for our operators to change tools—
yet another benefit of switching to the
lighter-weight carbon fiber tools.”
George Douglas, Schuler’s maintenance
supervisor and process engineer,
adds that “with aluminum, changing
one end effector was a two-man job.
With carbon fiber, while we still need a
second operator to help guide the end
effector to its nest, the tools are light
enough for one operator to carry. The
carbon-fiber tools also prove easier to
guide into place because of their
increased rigidity, which helps avoid
damage to magnets and other parts during
changeovers.”
Speaking of damage, Schuler found
that its older aluminum tools were
prone to bending or breaking in the
event of an occasional crash. Not so with
carbon-fiber tooling. Says Douglas:
“With carbon fiber, in the event of a
crash only one piece of the tool breaks,
and there are no bending problems.
This makes crash recovery much simpler
and quicker. And, there’s no dust
like there is with aluminum.”
The Transition is Complete
In spite of the misconceptions surrounding
carbon fiber, the benefits of
developing a lighter, stiffer and more
harmonically stable tool was a challenge
that Schuler could not afford to
overlook. The value proposition of
using carbon fiber over aluminum or
steel is justified in the design and construction
of stamping and body-shop
end tooling, particularly in high-speed
robotic applications.
Recently, Schuler’s facility has made
the transition complete. According to
Zeleji, “the entire shop is now fully realizing
the benefits of carbon fiber, and
there hasn’t been a single instance
where we have not been able to use it.
There has been no call to develop special
tubing profiles—everything has
been issued in standard stock. Aside
from having to develop some custom
bracketry, carbon fiber is working on
everything.”
MF
Article provided by Bilsing Automation:
www.bilsing-automation.com;
586/463-0686.
26 MetalForming/June 2011 www.metalformingmagazine.com