ModernMachineShop_June2011

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MULTITASKING?(Its a multIple-choIce questIon....)

JUNE 2011mmnne.cm

MULTITASKING?t i i

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Pepne Fm:


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and tilted and less pronounced on machines with

an articulated head that tilts and swivels the cut-

ting tool.As it is, all types o ive-axis machines are

becoming more popular. In response, a number

o suppliers have developed special workholding

systems to address the peculiar di iculties with

ixturing that can arise.

The main objectives o special ive-axis work-

holding systems are to lit the workpiece away

rom the worktable surace, position it in the best

location/orientation or CNC operations and grip

it securely. Other competing considerations alsoinluence the design o these special systems, so

they dier in their style and coniguration. Users

must careully evaluate how well the various

choices meet their needs.

Design characteristics to consider include

lexibility, modularity, rigidity, clamping secur ity,

aordability, part location repeatability and com-

patibility with other workholding systems. Also

worth considering are how quickly a setup can

be put together or changed over, how easilycomponents can be customized and how well

components can be adapted or possible use on

turning equipment, horizontal machines, grinders

or coordinate measuring machines.

A quick look at a ew o these systems shows

the range o oerings and brings attention to

some key concepts or developing an eective

ive-axis workholding strategy.

WorkholdiNg oN a PEdEstal

A distinctive eature o several ive-axis workhold-

ing systems is a basic pedestal-style ixture with

a round or square oot and sloping or cone-shaped

sides that give it a tapered proile. The height o

the proile lits the workpiece away rom the table

or clearance, while the taper increases exposure

o the machinable workpiece suraces above.

Another distinctive eature ound on some o

these pedestal ix tures is dovetail clamping.

Opposing clamping suraces have angled groovesthat interace with matching grooves machined

into excess material along the underside o the

workpiece. (This dovetail strip must be removed

Jergens modular system includes all of the elements

to lift the workpiece from the table, provide secure

clamping and keep machinable surfaces unob-

structed. The underlying subplate enables an entire

setup to be taken on and off the machine quickly.

doVEtail VisE

sElF-CENtEriNg

VisE

VisE adaPtEr

FixtUrE PlatE

toP tooliNg

roUNd PallEt

FlaNgE risEr

CENtEr

loCatiNg PiN

ball loCk

shaNk

JErgENs

sUbPlatE

rom the workpiec e later.) When the i xture

engages the dovetail strip under the workpiece,

the resulting joint is extremely strong and secure.


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The strength o this dovetail joint requires that

only a l i t t le extra stock be al lowed on the

workpiece.

Typically, pedestal ix ture systems include a

variety o sub/baseplates, risers, and adapters

or modularity and lexibility. One o the mostextensive systems currently available is the 5-Axis

Quick Change Fixturing System rom Jergens,

Inc. (Cleveland, Ohio). As you might guess, the

company promotes the quick-change eatures

and options that the system provides. As a oun-

dation, subplates with a variety o shapes and

bolthole patterns enable mounting the system to

any machine or rotary table, the company says.

The subplate can be conigured with the com-

panys proprietary Ball Lock Mounting System orQLS (Quick Locating System) so that it can be

removed rom the machine rapidly.

A range o pedestal risers can be mounted to

the subplate (also using optional quick-tighten/

quick-release bolts) to suit the size o workpiece

and provide the desired height rom the table top.

The topplate or the riser can be either an adapter

plate or the companys Drop & Lock Pallet Changer.

The latter enables the clamping element, with

appropriate pull studs attached, to be droppedinto place and secured with two turns o a hex

wrench. The clamping element can be a dovetail

vise or a ive-axis, sel-centering vise with two

movable jaws. Both types o vises are available

in a range o sizes and styles. All components in

the system are made o steel.

The company also emphasizes the importance

o its systems provisions or repeatable locatingand positioning o its quick-change ixturing

elements. This is accomplished with center locat-

ing pins or t iming pins between interacing

components.

dEdiCatEd FixtUriNg

Another modular system eaturing tapered ped-

estal-style ixtures with dovetail clamping is oered

by Raptor Workholding Products (Burbank,

Caliornia). Developed collaboratively by twoaerospace job shops in Southern Caliornia, this

system is tailored or shops using palletized

production cells built around ive-axis machining

centers. The basic dovetail ixture, made o

anodized aluminum or stainless steel, is available

in several sizes. The ixture can be mounted on

T-slots or the threaded holes o the standard

pallets used on the production cells. Several styles

o adapter plates enable the dovetail ixtures to

be mounted on the tables or rotary devices ospeciic models o machine tools rom certain

builders. Optional risers can provide additional

The modular assembly on the left consists of a

Jergens 250-mm flanged riser beneath a 130-mm

adapter and self-centering vise. For dovetail clamp-

ing, the adapter and its vise could be replaced with

a dovetail vise such as the 130-mm version shown

at the right. Dovetail clamping creates a strong, rigid

joint between the workpiece and the fixture.


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height to the ixture proile or greater clearance.The company reports that many users leave

multiple dovetail ixtures attached to the pallets

so that they become dedicated workholding setups

or repeat jobs. For this reason, aordability o

the ixtures is important.

According to the developers, several eatures

set the basic Raptor ixture apart rom other

designs. For example, a dovetail interace on one

side o the ixture serves as a solid stop against

which a workpiece is secured by the spring-loaded,stainless steel dovetail clamps on the opposite

side. Another eature, a locating screw adjacent

to the solid stop, provides workpiece positioning

and prevents a part rom being loaded backwards.

For workholding purposes, a shallow dovetail strip

must be machined on the clamping side o the

workpiece. This strip is only 1/8-inch high, so it

requires little extra stock. A slot that its against

a locating screw must also be milled. To load a

workpiece on the ix ture, the operator simply

places one side o the dovetail strip against the

solid side o the ixture and then tightens the

clamps. This presses the material irmly against

the solid side. The screws in the clamps are then

tightened to secure the workpiece.

The Raptor system now includes a line o

modular workholding ixtures that mount on top

o existing ixture components. These modular

ixtures enable a shop to adapt to dierent sizeso workpieces without having to remove ixtures

rom the machine pallet. The company creates

additional lexibility by oering components that

are compatible with its original dovetail ixtures.

For example, a 23-inch-tall tombstone can hold

three Raptor ixtures on each o its our sides. A

2X plate bolts two ixtures in a row or clamping

long parts. A Dual Raptor ixture holds two parts

by combining two sets o dovetail clamping zones,

one on each side. The our-sided Raptor Nesthas our stations or clamping ixtures.

VisEs that staNd tall

Vises that clamp with movable jaws have been a

proven workholding method or milling operations

since the earliest days o machining. The design

and construction o these devices have evolved

A dovetail strip on the underside of the blank

workpiece interfaces with the dovetail features on

the fixture. The Raptor RWP-001 pedestal fixture has

a dovetail slot 1.5 inches wide. The blank measures

about 4 inches wide, 6 inches long and 7 inches high

and produced the part shown on page 82.

Clamping fixtures mounted to clamping fixtures

extend the modularity of the Raptor system.


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along with developments in CNC machining

technology. Not surprisingly, vises designed

to meet the objectives o ive-axis workholding

have appeared.

Essentially, these vises eature uprights that

hold the workpiece at a suitable distance abovethe worktable. To keep the uprights rom spread-

ing at the top when clamping orces are applied

below, the clamping screw is situated close to

the clamping suraces.

An example o such a system is the Maxlock

350 multi-axis Anglock vise rom Kurt Manuac-

turing Inc. (Minneapolis, Minnesota). On one

side, the stationary jaw sits atop a 4.625-inch-

tall upright that can be mounted to a standard

2-inch by 2-inch grid pattern. An optional riser is

available to lit it another 3 inches and will it on

a grid patterns as large as 100 mm. The movablejaw, which has a 0.625-inch stroke, rides on

its own base (which can also be used with an

optional riser).

The clamping screw is located at the top o the

uprights near the clamping surace. It delivers as

much as 7,000 pounds o clamping orce at 40

oot-pounds o input torque. Available screw

lengths o 8, 12, 18 and 24 inches enable the

vise to handle any part that its on the worktable.

With this modular design, the minimum jaw open-ing is 0.15 inch and the maximum is 15.5 inches

with the standard screw lengths. The jaws are 3.5

inches wide. The Anglock eature o this vise

High-profile vises such as Kurts Maxlock 350 are

designed so that clamping forces are applied near

the workpiece surface. It is shown here mounted on a

T-slot table with optional risers.

reers to the companys proprietary design o the

internal screw nut that creates downward orce

on the workpiece proportional to the sideward

clamping orce exerted by the vise jaws. Part o

Kurts original innovations in vise design, the

Anglock principle counteracts the tendency o apart to li t as the jaws tighten, thus negatively

aecting their grip.

ProtECtiNg thE iNVEstMENt

For most shops, the move to ive-axis machining

represents a considerable investment that

includes not only the machine tool, but perhaps

also cutt ing tools, programming sotware

and workholding ixtures. It doesnt make eco-

nomic sense to skimp on products i they needto be upgraded to get the most out o ive-axis

machining capability.

When it comes to ive-axis workholding, a shop

has to decide i acquiring a commercial ive-axis

workholding system represents a better value

than making some or all o the ix tures and com-

ponents in-house. In this decision, the most

important actor is likely to be response time

getting the setup ready as quickly as possible. In

that case, the lexibility and modularity o a com-plete system designed or ive axis-machining

may be hard to beat.

Reprinted from the June 2011

MODERN MACHINE SHOP Magazine and Copyright 2011

by Gardner Publications, Inc.,

6915 Valley Ave., Cincinnati, Ohio 45244-3029.

For more information on Jergens Fixture

Pro 5-Axis Quick Change Fix turing

System, contact us.

Jrg, I.

15700 s Wr Rd

cvd, oh 44110

www.jrgi.

p: 877-426-2504

ei: wrkdig@jrgi.

ModernMachineShop_June2011

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