|
Twenty-Four Kurt Cluster Tower FMS Gives
Choice Precision Maximum
Setup Versatility While Operating Its Twin Machining Centers Non-Stop
Whitehall, Pennsylvania: Quick change workholding systems continue to
multiply and become more flexible in the job shop environment. Just a
few years ago, seeing a twin pallet machine with a cluster tower setup
on each pallet was leading edge technology. Many of these employed hard
tooling but weren't very flexible. Where vises were used on the towers,
they lacked today's machined changeable jaws and other features which
made them really flexible.
Now, the most progressive job shops are being equipped with true, flexible
machining systems which combine two machines, a palletized robot and
numerous cluster towers. These workholding towers are quickly and easily
loaded off-line on moving pallets and are preprogrammed to automatically
move in and out of the machining centers. The workholding is very flexible
because it employs machined, changeable jawplates which preclude dedicated
fixturing.
 |
| Finish machined parts in Kurt
Cluster Towers at Choice Precision Machine Inc. are ready for offline
removal from the workholding. The Mazak machining system utilizes 20
towers in the setup. |
The objective is to keep those machining centers in the cut nonstop,
even when machining different parts and the part run varies from a few
pieces to hundreds. Kurt Cluster Towers, with a large variety of clamping
options, make it possible. Doing the setups offline on the Kurt Cluster
Towers is the key and it's no longer just an option, it's required for
maximum flexibility and cost effectiveness. With today's multi-task, easily
programmed machining centers, the more towers you can load and have ready
on a robotized pallet, the longer the machines can operate non-stop and
much of the time unattended.
The wisdom in this approach has been captured at Choice Precision Machine,
Inc., Whitehall, Pennsylvania, where it uses 30 Kurt Cluster Towers,
24 of which are dedicated to one twin Mazak Palletech system setup.
This system is used to machine parts used in inserting systems for large
newspapers, to automated stuffing and sealing systems, to oil riggers
and biotech systems.
Choice Precision is a relatively new company having started in 1992.
Not burdened with old technology and the thinking behind it, this company
looks and acts innovative in every respect. With 30 highly trained workers,
Choice Precision's new building is filled with a dozen of the latest horizontal
and vertical machining centers, computer aided design facilities, a long
list of support equipment, and the best gaging and test equipment.
 |
|
All part shapes, sizes and
materials like many of these by Choice Precision are held with
repeatable precision in Kurt Cluster Towers using machined jaws. |
The precision parts Choice Precision manufactures aren't of the everyday
variety either. Many are made from Inconel, Hastaloy and stainless. Some
even from composites, PVC and Delrin. Tolerances are tight, as close as
.0002".
Large FMS Setup Is Beneficial To Widely
Varying Part Run Needs
"Our customers might need one part or 3000," reports Mike Stufflet, shop
supervisor for Choice Precision. "One part run of 500 pieces might take
a day to run while a really complex part might require a full month to
run just 100 pieces. The variation in part complexity and turnaround time
required is really broad. But with our offline setups, using the Kurt
Cluster Towers and machined Kurt jaws in the Mazak Palletech system, we're
really able to maximize our productivity. One tower is in process all
the time and the other towers are in queue."
"With our careful scheduling, one of the two Mazaks alternately operates
24 hours a day, six days a week. We have two operators for this Palletech
system -- one works 10 hours and the other works 11 hours a day. By staggering
the shifts and production flow, we are able to run one and sometimes both
Mazaks continuously and for long periods unattended. We're doing a lot
of high speed material removal and this FMS setup is the most efficient
for serving our customers' just-in-time needs."
It should be noted that with the Palletech system's unique controller,
Choice Precision can randomly select different parts for machining or
produce the same part back-to-back without interruptions. Dynamic scheduling
also allows easy part selection for rush jobs.
Kurt Vise Towers Are Key To Expanded Part
Holding Capabilities Of The FMS
 |
| Keeping parts square
and perpendicular like those pictured is easy because all clamping
surfaces are precision machined. Also, the Anglock® design
of the vise assures that the movable jaw does not lift. |
Choice Precision's twin FH580/40 Mazaks operate at up to 12,000 rpm with
tool change time of 3.0 seconds (chip to chip). These machines are used
for a combination of milling, drilling, tapping and boring operations.
They have rapid traverse rates up of 1968 ipm in all axes and up to 15
horsepower in the spindle. They are equipped with automatic tool changers
that carry 120 tools each. Their maximum long travel is 28"(X), maximum
cross travel is 24"(Y), and maximum spindle travel is 25"(Z).
"We run these machines right up to their maximum 12,000 rpm with high
feed rates," reports Stufflet. "So we need very rigid workholding. We
chose the ductile iron Kurt Cluster Towers over aluminum workholding
devices because of their rigidity and stability. 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." Made
of 80,000 psi ductile iron, these Kurt CT6 D4 Cluster Towers have a stiffness
of 2.5 times that of aluminum (the vibration damping of ductile iron is
20 times higher than aluminum). To provide high density users like Choice
Precision optimal clamping choices, Kurt offers several interchangeable
jaw plate options. The clamping accuracy of these options is dependent
on the vise clamping mechanism and its accuracy. Insuring this, all vise
bodies in the six inch tower employ the Anglock design which assures that
moveable jaw does not lift. Also, vise beds are hardened as are the jaw
plates.
Each vise has a hard steel screw which clamps quickly and easily by
hand with a force up to 10,000 lbs. that converts to precise, repeatable
gripping force.
Choice Precision machines its Vise Tower jaws to fit individual part
holding requirements. Where needed, these customized jaws provide ± .001
repeatable part clamping accuracy. They are an economical substitute for
heavy, hard to move dedicated fixturing and they are easily organized
and stored near the pallet system.
"This is a good system because all of the components, from the machines
themselves to the workholding towers and jaws, are modular," said Stufflet.
"We can add up to eight more machines, extend the pallet and add workholding
towers as our needs grow."
|
