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Painted Feather Precision Improves Productivity
By Adding
Kurt Vise Towers ' Rigidity Helps Greatly Reduce Scrap
Minneapolis, Minnesota: More and more precision machine parts manufacturers
these days are changing over from single and double station vise setups
to ClusterTowers as a quick way to ramp-up part production while retaining
flexibility for changing part requirements.
Not only are vise towers a good way to get more out of existing machines,
they're an instantaneous solution because these workholding devices are
available on short lead times and machine operators can put them to work
at top production levels in just minutes.
What's interesting is that many shops, like Painted Feather Precision,
are taking an aggressive approach converting many of their older single
and double station workholding setups to eight station cluster towers
because it makes good economic sense to do so.
Painted Feather Precision did exactly that to meet an important customer's
rush need for greatly increased part quantities. With four horizontal
machining centers dedicated to the project (a new Toyoda FA450-3 and an
existing Mitsui Seiki HT3A), Painted Feather Precision equipped both machines
with two Kurt CT 640 ClusterTowers. But the company didn't stop there.
With support from its customer, it went ahead and purchased an additional
6 ClusterTowers for additional part quantities, including parts currently
in design and engineering. In that situation, the ClusterTowers would
be ready to mount with custom jaw plates on existing machining centers.
If the part quantity requirements stayed constant, the extra 6 ClusterTowers
could be used easily for other projects. (Photo One and Photo Two)
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PHOTO ONE CAPTION: Brian Maciej (left) and Bob
Johnston, co-plant managers for Painted Feather Precision with their
new Kurt ClusterTower workholding setup on a Toyoda FA 450-3 machining
center.
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PHOTO TWO CAPTION: Finish machined carriage assembly
parts in the Kurt ClusterTower have numerous surfaces, interior
curves and tapped holes. True position tolerance requirement is
.003" with average tolerance requirements of .005".
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Kurt ClusterTower Setup Reduces Machining
Time by 11.5% Per Part.
"We're a 24-hour- a-day, 5-1/2 day-a-week operation with the goal of
having all of our machines in the cut operating at highest speeds possible
at all times," reports Bob Johnston and Brian Maciej, co-plant managers.
"That calls for flexible high density workholding that can really hold
parts rigidly. Kurt Clusters Towers give us extra production capacity
and the rigidity so we can operate our machines at top speeds. We used
a few aluminum vise towers before and knew the advantages, but this was
our first experience with Kurt, which is made of ductile iron. Now throughput
on our new Toyoda FA450-3 is 11.5% faster per part than with the previous
setup and 9.75% faster per part on the Mitsui-Seiki HT3A. Another important
advantage is that our machine operators can leave those machines for extended
periods to do other jobs after loading the sixteen stations on the two
ClusterTowers."
A true high density workholding setup, all operating time is productive
compared to the previous setup of twin station vises. With eight parts
completed simultaneously, the machine operator has time to load unfinished
parts, unload finished parts, check for burrs and measure each for accuracy
and still do other operations such as queuing up parts on nearby machines.
Painted Feather Precision Wins Machining
Awards
Painted Feather Precision was founded in 1978 as a single-owned minority
business that has earned a reputation for top notch precision machining
work with leading aerospace and defense contractors. Its customer list
is a "who's who" of leading defense suppliers including Rockwell Collins,
Lockheed Martin, ITT Aerospace and McDonnell Douglas/Boeing. The company
has received numerous awards for its work, including Supplier of the Year
from Rockwell International and the Award of Excellence from the U.S.
Small Business Administration.
 Well
equipped and highly disciplined, Painted Feather Precision has 40 employees
and a bakers dozen of the latest horizontal and vertical machining centers,
several with speed capabilities to 20,000 rpm. It has complete computer
aided design, a long list of support equipment and the best gauging and
test equipment.
The parts Painted Feather Precision manufactures aren't garden variety
either. In addition to aerospace aluminum, investment & die castings,
parts are machined from magnesium, copper and berrilium. Tolerances are
typically tight, as close as .0002". (Photo Three)
PHOTO THREE CAPTION: Complete parts precision machined
by Painted Feather Precision made from bar stock to state-of-the-art investment
castings. Parts pictured are used in navigation and communication equipment,
ordinance devices and operating room medical machines.
Speed And Rigidity Is The Name Of The Workholding
Game
Seeking to broaden its customer base into commercial products, Painted
Feather Precision won a developmental contract for machined parts for
new diagnostic X-ray systems. When this system became successful in the
medical marketplace, the company had to ramp-up quickly or lose the project.
"Our existing equipment and setups couldn't handle the increase," reported
Johnston and Maciej. "We knew we had to add another horizontal machining
center but we wanted to better utilize existing machining centers as well.
We wanted to be able to handle the larger quantities required for the
X-ray project but also be equipped for shorter turnaround times on new
commercial projects."
"We looked at workholding from four different suppliers and needed the
ClusterTowers immediately. We had to have the best workholding rigidity
because of the aggressive speeds we operate our machining centers at.
We wanted to optimize the machining programs and take full advantage of
the machine's top speed both for roughing and finishing operations without
compromising tolerance requirements and overall part quality. We decided
on Kurt's CT 640 ClusterTowers because we knew about their patented AngLock
feature and were confident they had the holding rigidity to do the job,
and we could get the Kurt towers in just a few weeks, which included customizing
the base for each to a 400 mm square dimension to fit our machines' pallets."
The two X-ray system parts used in a carriage assembly are made from
6061-T651 aluminum and when finished measure 4-1/2 in. x 4-1/2 in. x 1
in. with average tolerance requirements of ± .005". One part has a true
position tolerance requirement of .003" which is machined on the FA 450-III
Toyoda machining center, a good choice for this work because it handles
heavy chip loads with speed and precision. Equipped with dual indexable
pallets, it has a top speed of 14,000 rpm with cutting feed and rapid
traverse of 1890 ipm in the x, y and z axis. It has a 65 in. x 55 in.
x 45 in. work area that easily accommodates the Kurt ClusterTowers, has
a 40 taper, 60 tool holder carousel, and is equipped with a GE Fanuc CNC
control.
The parts require heavy material removal and are milled, drilled and
tapped at roughing speeds of 240 in/mn and finishing speeds of 120 in/mn.
The FA 450 is operated continuously with 40 parts completed per 24 hour
period, manufacturing at maximum capacity work force hours. According
to Johnston and Maciej, "The part repeatability has been so good that
rejects are virtually non-existent, along with an increase in yield, due
to the 25% reduction in scraped parts, since this project was initiated."
 Clamping
Rigidity Of Kurt ClusterTowers Provides Best Solution
Made of 80,000 psi ductile iron with a stiffness 2.5 that of aluminum
(the vibration damping of ductile iron is 20 times higher than aluminum),
Kurt ClusterTowers eliminate cutter induced vibration reducing the chance
for inaccurate parts and resulting scrap. The jaw clamping system in each
of the tower's four vises employs the Kurt AngLock feature so as to minimize
moveable jaw lift. Each vise has a hard steel screw that clamps quickly
and easily by hand with a force up to 6,316 lbs. That converts to precise,
repeatable clamping. The clamping mechanism itself is isolated with a
guard protecting it from chips and coolant, making cleanup between load/unload
operations fast and easy. (Photo Four)
PHOTO FOUR CAPTION: Kurt ClusterTower is highly rigid
to achieve workpiece immobility and to dampen cutter induced vibration
To help facilitate high speed operation of the X-ray parts, Painted Feather
Precision machined its own custom vise jaws. These jaws fit into the tower
vises 2-3/4 in. high (standard is 1-3/4 in. high) so as to hold parts
out from the clamping station to allow cutting tools, coolant and chips
to move more freely. It machines two basic jaw styles for its operations
' knife jaws for holding raw stock and step jaws for finishing operations.
(Kurt offers several interchangeable jaw plate options for users who prefer
not to make their own jaw plates).
"Going with the Kurt ClusterTowers was a good decision," said Johnston
and Maciej. "We surprised ourselves at the improved productivity. A lot
of seemingly small efficiencies added together, like a little faster feeds
and speeds, less machine travel from part to part, more efficient operators,
not to mention scrap elimination, make a big difference. And everything
is modular. We can change machines and Kurt ClusterTower combinations
as our needs change."
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