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Adding A Flexible Kurt™ CarvLock™
ClusterTower™ Setup Used Alongside Of
A Dedicated Fixture Maximizes Machine Output While Providing Flexible
Workholding
Kansas City, Missouri: More and more companies these days are finding
that by juggling work scheduling on their machining centers and adding
a vise tower setup on the right machine, they can increase productivity
without adding operating hours.
That was the case at Civacon/Knappco. When the company needed to increase
product output to meet increasing demand for its check valves and cargo
tank fill covers, it looked at rescheduling the work on the machines it
had along with a different approach for its workholding.
By combining a new Kurt CarvLock™ ClusterTower™ setup using
machinable jaws on one pallet of a twin pallet Mazak FH680 4 axes mill
alongside of a dedicated holding fixture on the second machine pallet,
machining output was increased significantly. The new process freed up
the machine previously used for another part project. Productivity was
increased for all three machining projects without adding man-hours or
new machines. (Photos One and Two)
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Photos One and Two Caption: Twin pallet Mazak FH680
4-axes mill has a flexible Kurt CarvLock ClusterTower on one pallet
to hold different size check valves. The second pallet is a dedicated
fixture for holding manhole fill covers.
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Knappco Corp. is a specialized manufacturer of industrial access ports,
manholes, hatches, coamings, collars, weld rings, fill covers and check
valves used in the handling, transport and storage of petrochemicals,
agricultural commodities and building materials such as cement and asphalt.
When used in a system, these products are designed to deliver safe, fast,
loading and unloading while safeguarding against costly spills, tank overfills
and dangerous fugitive emissions.
Many of Knappco's products require precision machined components produced
in small to medium quantities, (300 to 5,000 parts). For one product assembly,
the company had been machining precision die cast aluminum check valves
on a Mazak Integrex combination lathe/mill, completing just one check
valve at a time. The parts require turning, milling, drilling and tapping.
The machining process was adequate but required too much operator attention
during the load, unload, deburr and inspect sequence for each valve. Since
volume requirements for the check valves were growing and the machine
was needed for other work, Knappco engineers investigated alternative
ways to utilize their machining centers, including installing a Kurt CarvLock
ClusterTower equipped with machinable jaws.
 "It
was a case of making the most of the resources we already had," reported
Don Burgher, check valve and manhole fill cover team leader. "The Kurt
CarvLock ClusterTower setup helped us add capacity and gave us a versatile
workholding setup which could be changed to accommodate different parts.
And it allows us to add more cluster towers if we need to add more capacity."
(Photo Three)
Photo Three Caption: Getting more productivity and versatility
out of existing machines is possible through a change to high density
workholding. Don Burgher of Knappco holds a check valve finish machined
in his high density Kurt CarvLock ClusterTower.
Underutilized Machining Center Provides
Capacity For Two Projects
Knappco's 4 axes Mazak FH680 twin pallet machining center had been used
solely for machining large manhole fill covers. The setup employed custom
holding fixtures for these parts but wasn't being utilized to its full
capacity. Officials looked into moving the check valve machining operations
onto this machine, utilizing one of the pallets and a Kurt Vise Tower
equipped with DoubleLock Kurt vises on each of the towers' four faces.
The Mazak FH 680 machining center is a good choice for the check valve
machining work. It's a very flexible and powerful horizontal machining
center with 41.94" (1050 mm) X-axis, 31.50" (800 mm) Y-axis and 32.4"
(825 mm) Z-axis travel. It has 1260 IPM (32 m/min) rapid traverse, with
a spindle speed of 10,000 rpm powered by AC30kW (40HP) main spindle motor
(15 min. rating). With full multi-tasking machining capabilities, the
machine has the capacity, speed and programming flexibility for handling
both projects -- the larger 24" x 24" x 3" manhole fill covers on one
pallet and multiples of the smaller 5" x 5"x 7" check valves on the second
pallet.
It's all possible using a Kurt CarvLock ClusterTower Model CTU6 equipped
with four sets of 4" x 6" x 8" special cast iron jaws. There's no loss
of clamping rigidity in a setup like this because the Cluster Tower is
made of 80,000 psi ductile iron, and has a stiffness of 2.5 times that
of aluminum (the vibration damping of ductile iron is 20 times higher
than aluminum). The jaw clamping system in each of the four vises employs
the Kurt AngLock feature so as to minimize moveable jaw lift. Each vise
has a hard steel screw which clamps quickly and easily by hand with a
force up to 5,556 lbs. that converts to precise, repeatable clamping.
(A patented key design makes locating these jaw blocks very fast with
± .001 repeatability.)
The entire eight station workholding setup can be changed over for a
different part run in under five minutes -- one jaw set snaps out and
another jaw set snaps in with little effort in about sixty seconds. (Photo
Four) Another nice feature of this Kurt CarvLock ClusterTower system is
that there are four different jaw systems available -- machinable aluminum
or ductile iron jaws (in three heights), an EZLock quick-change jaw plate
system, and standard hard jaw plates. For the check valves, Knappco uses
the four sets of the 4" x 6" x 8" ductile iron jaws (Photo Five).
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Photo Four Caption: Kurt's high density workholding
systems have fast change jaw feature - change all three jaws in
a minute.
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Photo Five Caption: Moveable jaw blocks are indexable
and machinable on all four sides. Allows machining over bolt holes
in the stationary jaw. Stationary jaws are keyed to the vise base
for repeatability within .001".
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With high density workholding the name of the game these days, this setup
accomplishes it. Four parts are completed at a time, allowing the operator
time to load unfinished parts, unload finished checkvalves and to deburr
and measure each for accuracy. Unlike the previous setup on the combination
lathe/mill which completed only one part at a time and then was stopped
for unloading and reloading, this setup keeps parts in the cut at all
times, even during the load, unload, inspect and deburr sequence.
Machining operations include face milling, drilling, end milling for
circular interpolation, threading the diameter, counter bore, chamfer
boring and threading through holes, drilling side holes, counter boring
a side hole and face milling the seat face.
Tolerances are tight, ± .005 on the face dimension and overall height.
Drilling operations are done at 7500 rpm, facing operations at 1200 -
1500 rpm with feed rates to .020 per revolution. Fifty check valves are
completed on average per 8 hour work shift with 2 shifts operating a five
day work week.
Kurt CarvLock ClusterTower Is Key To Expanded
Part Holding Capability
"Besides being much faster than the previous setup, the operator's time
is better utilized," reports Burgher. "We run this setup as aggressively
as possible with high feed rates and that's possible because the workholding
is very rigid. That's why we chose Kurt. We don't have to worry about
vibration or chatter because the ductile iron vise bodies dampen any tendency
to vibrate when aggressive operations are called for."
"We like what we've done with this system because we expanded capacity
with modular components that are fully compatible with our dedicated fixtures.
Our Mazak FH680 is also expandable into a Palletech system of multiple
pallets for offline load/unload using more Kurt ClusterTowers if and when
we need them," said Burgher.
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