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.Tools should be hard, clean and sharp, and if possible,solely dedicated to composites containing KEVLAR*brand fiber. Use acetone or an equivalent for cleaning.Remember that cutting in the direction of the fibers willbe less difficult than cutting across the fibers.

clean them up. Tominimize vibrations,support or clamp thecomposite as close aspossible to the cuttingtool.

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.Backing the compositewith materials such as lucite@ acrylic sheet lor equiva-lent), aluminum, wood, or even cardboard before machin-ing lespecially drilling) will improve quality by helping tokeep tension on the fibers as they are cut. Backing acts asa close-tolerance, exit-side bushing. Ordinary maskingtape or painting the composite with a good primer will alsowork in many cases. Back both sides of the composite ifpossible. You can use Peramacel P-O2 double-faced tapeto attach backing to the composite.

.Cutting and machining composites containing KEVLA~can create a fine fibrous dust (fibrilsl which can beinhaled. A good exhaust system is important; however, ifone is not available, wear a respirator that has beenapproved by the National Institute for Occupational Safetyand Health (NIOSHI.

.Because of its high tensile strength, KEVLAR@ is tough to

cut. It's best to pre-load the fibers in tension while simulta-

neously cutting them in a shearing action. This principle

especially applies to machining composites reinforced

with KEVLAR@.

.Composites with resin-to-fiber ratios of 35% or above areusually easier to machine.

.It's very important to keep the composite from vibratingduring machining because vibrations can cause theresin to break ahead of the cutting tool, which in turnlessens the tension on the fibers and allows them tobe pulled instead of cleanly cut or sheared. The fiberedges will fuzz, requiring secondary edge finishing to

.Before beginning, it's always advisable to experiment withtools and procedures to evaluate which work best with

your particular composite.

*KEVLAR is a DuPont registered trademark.

A conventional steel blade with 14 to 22 teeth per inch isfine for composites containing KEVLAR@ brand fiber. Theteeth can be set in either Raker or standard position. To getthe best results, use a cutting speed between 3,000 and6,000 FPM and a slow feed rate of about 1-2 FPM.

In most cases it is best to mount the saw blade upside downso that the teeth are pointing up. This way the teeth will actas if they were knives and give a less aggressive, cleanercut. With a standard shop mechanic's honing stone, hone anew blade before using it to remove any burrs left by themanufacturing process. Burrs catch the fibers and pullthem, causing the fibers to fuzz.

For composites reinforced with KEVLAR@, use a blade withalternating teeth and a special guiding device. Speed rate:10,000-12,000 strokes/minute. Feed rate is material-depen-dent-very fast for thin composites, slower for others.Backing will improve cutting quality. Masking tape can alsoserve as a backing.

Water coolant is okay for heavy cuts.

Composite blends or hybrids are different:

.Blends like KEVLAR@/fiberglass or KEVLAR@/carbon are

much more abrasive and will quickly dull a conventional

steel blade.

Remember to support the composite as close to the sawblade as possible. This will hold any vibrations to a minimumand improve cutting quality.

Vendors (saber saw blades):

Pen Associates, Inc. Sears Roebuck and Go.P.O. Box 812 Blade Stock No.9-28804201 Pine Knoll Circle or No.9-28805Hockessin, Of 19707 (any outlet store)(302) 239-6866

.For these types of composites use a carbide-tipped blade

with 6 teeth per inch set in Raker fashion.

.Use a minimum speed of 5,200 FPM and a slow feed (1-2

FPMI rate forthe best results.

Finally, backing the composite acts as an exit-side bushingaround the blade and provides a much cleaner cut. Butwhether backing is used or not, mount the support (tooling)as close to the blade as possible. For table saws, the sawblade yoke should be set as close to the blade as possible.These steps will help minimize work piece and bladevibrations.

Vendors (carbide-tipped blades):

American Saw and Hol/oway Brothers ToolsManufacturing Co. 19 East Commons Blvd.301 Chestnut St. New Castle, DE 19720East Longmeadow, MA 01028 (302) 322-5441(413) 525-3961

The high energy generated by the circular saw may heat thecomposite's resin above its high temperature rating, causingthe resin to smoke and become tacky. Resin will accumulateon the blade Iblinding) and gum-up the edge. For this reason,we prefer not to use the circular sawto cut composites con-taining KEVLAR@. However, if you decide to use this tool, besure to use a carbide-tipped blade with an alternating toothangle. Remember, too, that backing the composite willimprove cutting quality. One last point-be careful!

If you are considering using a circular saw, contact DuPont.1-800-4-KEVLAR.

Vendors (Carbide-tipped blades for hybrids of KEVLAR@ ):

Heineman Saw Co. Remington Products2017 Navarre Rd. SW 60 Main StreetCanton, OH 44706 Bridgeport, CT 06604(330)456-4721 1-800-736-4648

A cutting tool of C-2 category cemented tungsten carbidebrazed to a steel shank is available on special order for turn-ing rods and tubes reinforced with KEVLAR@ brand fiber.The tool has been ground with a diamond wheel to provide

the correct relief and sharpness of the cutting edge.

Speed: 75-150 SMPM

Feed: 0.04-0.06 mm/rev

Depth of cuts: 0.2!}-0.50 mm

Mainly thought of as an electrical power tool belonging tothe medical profession, the cast cutter is a surprisingly safeand effective means for cutting composites reinforced

with KEVLAR@.

The blade does not rotate! Its cutting action is produced byhigh-speed oscillation. It cuts on both the forward and back-ward stroke, and if it comes in contact with the operator'sskin, in most cases, itwill do no harm.

With current equipment, however, it is a slow operation.

Vendor (custom tools):

Pen Associates, Inc.P.O. Box 812201 Pine Knoll CircleHockessin, DE 19707(302) 239-6866

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Tips:.Use blades: #840-40-300 1i-Ni Coated SST, 2"

#840-40-350 1i-Ni Coated SST, 2 X"

.Never use a dull blade. It could cause an injury-

.1ighten the blade retaining nut before each use.

.If possible, clamp the composite to minimize vibrations

and improve cutting quality-

.Too much pressure may cause the blade to break.

.Clean the blade before each cutting operation.

In most cases, a composite cut with the cast cutter requires

no additional edge finishing.

Vendor:

Stryker Instruments

4100 East Mi/ham Ave.

Ka/al?1azoo, M/49001

1-800-253-3210

Generally, turning is a more economical operation thanusing the circular saw; however, the edge quality is

somewhat inferior and will require additional secondary

edge finishing such as sanding.

2

Use a tungsten carbide cutting tool for parting filamentwound tubes made with KEVLAR@. This type of tool has awear life of approximately 300 cuts. Operating speed of

the tube is 320 RPM.

This hand tool does an excellent job cutting thin composites11/8" or less) that are reinforced with KEVLAR@ brand fiber.Because of its small size, it is good for contoured compos-ites or composites that, for whatever reason, cannot be cutwith a saber saw or a band saw.

The laser cutter is a fast, efficient way to cut compositescontaining KEVLAR@. It can easily handle parts with thick-nesses of up to 3/16". Edge charring, which occurs duringcutting, is easily removed with a common eraser. A ruby redor a pink pearl eraser will work fine. And because the lasercutter is so fast, it causes no edge delamination.

Contact tool manufacturers for details and application data.They will be happy to satisfy your cutting needs.

Note: Because the laser burns the composite material inthe cutting path, the resulting smoke contains numer-ous complex organic chemicals, some of which areirritating ortoxic. Be sure to exhaust the smoke awayfrom the mechanic, and do not recirculate this airbefore first purifying it le.g., passing throughactivated charcoall.

Pneumatic types require a water-free air supply of 90-100PSI and should operate at 20,000 RPM j12,000 RPM minimumfor electric typesl. Run the tool at full speed for better cut-ting, and use a Norton AlundumTM fiberglass-reinforcedgrinding wheel j3" dia. x .035" thicknessl or equivalent.

Tips:.If possjble, clamp the work piece to lessen vibrations and

improve cutting quality-

.Be sure to follow all of the manufacturer's safety precau-tions and the operating and maintenance instructions.

.Back both sides of the composite if possible. Masking tapewill work as a backing if other materials aren't available.

Vendors:

Cooper Power Tools (Dotco) Snap-Dn ToolsP.O. Box 1410 1330 Enterprise Dr.Lexington, SC 29071 West Chester, PA 193801-800-845-5629 1-800-926-5544

Vendors:

Covergent Energy Laser Applications Inc.1 Picker Road (Contract processor)

Sturbridge, MA 01566 1110 Business Parkway South

1-800-722-1133 Westminster, MD21157

(410) 857-0770

The above manufacturers are interested in doing test

development work.

Nol1on Co. (cutting disks)

I New Bond Street

?0. Box 15008

Worcester, MA 01615-0008

1-800-543-4335

Use this tool for cutting thin composites reinforced withKEVLAR@.

Contact manufacturers for details and application data.They will be happy to satisfy your cutting needs.

Vendors:

Branson Ultrasonic American GFM41 Eagle Road 1200 Cavalier Blvd.Danbury, CT 06813 Chesapeake, VA 23323(203) 796-0400 (757) 487-2442

3

Computer controlled for incredible accuracy, the water jet

cutter is a precise, high-quality method for cutting compos-ites containing KEVLAR@ brand fiber. Because there is noheat build up or edge delamination, secondary edge finish-

ing, in most cases, is completely unnecessary.

A sickle-shaped, brad point modified twist drill of tungstencarbide provides the best results when drilling a compositeof KEVLAR@. The sickle-shaped cutting edges keep thefibers in tension while cutting them in shear. These edgesare quite aggressive and can pull the drill though thecomposite so quickly that some fibers may be left uncut.Forthis reason, use this drill with controlled-feed machines.

Note: If you must use a drill other than the modified twist

drill, you'll get better results with a controlled-feed machine.

Remember to:

.Clamp the composite to minimize vibrations.

Be sure to use an abrasive grit when cutting a compositeof KEVLAR@. The grit comes in various grades but type 120

HP will satisfy most needs. Normal cutting pressure rangesbetween 25,000 and 45,000 PSI, but for thicker parts, it canreach as high as 60,000 PSI. The cutting stream can travelthree times the speed of sound. And because the compositeis only exposed to water for just a short time, moisture

absorption is not a problem.

One other point: since this operation is wet, there is littlechance that the KEVLAR@ fibrils created during cutting canbe inhaled; however, we advise you to clean the machineimmediately after use, while it is still wet. Once it dries, theKEVLAR@ fibrils can become airborne and may be inhaled.

.Back the composite and use guide bushings to improve

the quality.

.Keep the tool from overheating. This will prevent the resin

from melting.

.Use controlled feed.For more information, contact the manufacturer.

Vendors:

Flow International Ingersol1 Rand Co.P.O. Box 97040 McCartney Mfg. Div.Kent, WA 98064-9740 P.O. Box 2311-800-446-3569 Baxter Springs, KS 66713

(316) 856-2151

Jet Edge Carp.825 Rhode 'sland Ave. S.

Minneapolis, MN 55426

1-800-538-3343

.Contact the manufacturer for special sharpeninginstructions or return to the manufacturer for sharpening.

Operate between 6,000 and 25,000 RPM with a slow,controlled feed rate. Fiber volume and resin content are keyfactors in determining the speed and feed rates. Also, as you

increase the drill size, remember to decrease the speed.With a smaller drill, use a faster speed. Generally, when

drilling, it's high speed, slow feed. If possible, experimentwith a sample piece of the composite to determine the

optimum rates.

Vendors:Guhring International Carbide Corp.1445 Commerce Ave. 305 B Creek St. NortheastBrookfield, WI53045 Yelm, WA 98597-9421(414) 784-6730 1-800-422-8665

Pen Associates, Inc.P.O. Box 812201 Pine Knoll CircleHockessin, Of 19707(302) 239-6866

.1.

For composites containing KEVLA~, use the core drill ifthe resin content is 20% or less. Operate at low tool speedbetween 3~O SFPM.

Vendor:

International Carbide Corp.305 B Creek St. NortheastYelm, WA 98597-94211-800-422-8665

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Single Flute Drill

:Hoeing Patent~

Use this tool only when the sickle-shaped, brad pointmodified twist drill cannot be used (e.g., for KEVLA~ brandfiber/metal composites, extremely hard materials, or whenusing a thick metal tool guide). The European version is thesingle point PKD drill (Iscar patent). This type has a singleperipheral cutting edge, and the PKD signifies a polycrys-talline diamond insert.

Vendor:

Starlite IndustriesP.O. Box 9901111 LancasterAvenueRosemont, PA 19010(610) 527-1300

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When drilling composites containing KEVLAR<BJ, use themodified twist drill (brad point) with any of the following:

.Desoutter CFD 20,000 RPM for 3-6 mm holes.

.Dotco 20,000 RPM for 3-6 mm holes.

.Desoutter CFD 9,500 RPM for 8-10 mm holes.

Operating at a high speed and a slow feed rate will providea cleaner exit hole, but just remember to keep the tool fromoverheating. By doing this, you'll prevent the resin frommelting and you'll extend the life of the tool. Check the tooloften and clean it as necessary.

Use a tungsten carbide type drill with a 150-200 degreeangle and no serrations. Use it only with a drill press orwith drill guides. High speed operation is preferable, that is,250--450 SFPM with a medium to rapid feed depending onthe material. Backing the composite will give better results.

This tool is recommended for thin composites made withKEVLAR@ 1< .020"1 when the sickle-shaped, brad point modi-fied twist drill can't be used le.g., for holes less than .125"diameter). Also, it can be an inexpensive alternative whenonlya few holes are required.

Vendors:

International Carbide Corp. Pen Associates, Inc.305 B Creek St. Northeast P.O. Box 812Yelm, WA 98597-9421 201 Pine Knoll Circle1-800-422-8665 Hockessin, Of 19707

(302) 239-6866

For better quality, it's best to clamp the work piece and use

guide bushings.

Vendors:

Desoutter Inc. (USA Dist.) Cooper Power Tools (Dotco)

24415 Ha/stead Rd. P.O. Box 1410

Farmington Hi/Is, M/48335 Lexington, SC 29071

(248) 476-5358 1-800-845-5629

TAl Lubricants

P.O. Box 1579

Hockessin, DE 19707

(302) 326-0200

Snap-On Tools

1330 Enterprise Dr.

West Chester, PA 19380

1-800-926-5544

5

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This type of controlled feed drill has a C-shaped yoke thatautomatically clamps the composite piece during drilling.For best results the bushing of the C yoke must fit tightly(.001"-.0021 with the drill diameter. Templates arerecommended for positioning the holes.

Use a conventional steel twist drill for composites contain-ing KEVLAR@ brand fiber. Composite thickness should be nogreater than .125". Drills with peripheral cutting edges (bradpoint) should not be used because chips can't be properlyremoved when bushing clearances are tight. .For a clean entrance and exit, quickly penetrate the

composite until the center line of the tool is approximatelymid-way between the entrance and exit surfaces.

.While continuing to operate the drill motor, rapidly move

the tool in an orbital manner for a few seconds. This allows

the cutting edges to shear any uncut fibers toward the

center of the composite thickness.

.To achieve a properly dimensioned hole, keep any radial

movement of the tool to a minimum.

Finally, do not use this tool for resin-Iean composites or for

drilling into an underlying metal support.This drill is not generally acceptable for composites contain-ing KEVLAR@; however, when used in combination with aclamping C yoke and only after both sides of the compositehave been backed, a new drill of this type will produce

acceptable results.

Vendor:

Pen Associates, Inc.

P.O. Box 812

201 Pine Knoll Circle

Hockessin, Of 19707

(302) 239-6866

DuPont Toray Company, Inc.

1-5-6 Nihombashi-Honcho,

Chuo-ku, Tokyo 103

JapanTel: 81-3-3245-5080

Fax: 81-3-3242-3183

DuPont Engineering Fibres

P.O. Box 50

CH-1218 Le Grand-Saconnex

Geneva, Switzerland

Tel: ++41-22-7175111

Fax: ++41-22-7176021

Address Listings for Literature-KEVLAW Brand Products

DuPont Advanced DuPont Canada Inc.Fibers Systems Advanced Fibers SystemsCustomer Inquiry Center P.O. Box 22005401 Jefferson Davis Highway Streetsville Postal StationRichmond, VA 23234 7070 Mississauga RoadTel: (800) 453-8527 Mississauga, Ontario L5M 2H3

(804) 383-4400 Tel: (905) 821-5193Fax: (800) 787-7086

(804)383-3963

A Few Closing Remarks .-

We believe this information is the best currently available on the subject. It is offered as a possible helpful suggestion in experimentation you may care to undertake along these lines.

It is subject to revision as additional knowledge and experience are gained. DuPont makes no guarantee of results and assumes no obligation or liability whatsoever in connection

with this information. This publication is not a license to operate under, or intended to suggest infringement of, any existing patents. H-62647-11

When the exit side of the composite is impossible to backor when other considerations prevent the use of the toolsalready discussed, use a single-point, self-centering serrateddrill with up-and-down cutting flutes. Although this drill canproduce an acceptable hole in a composite containingKEVLAR@, it is a highly specialized tool that requires a greatdegree of skill on the part of the machinist. Therefore, we donot suggest it for general use.

Nevertheless, if you do use it, here are a few helpful tips:

Accurate holes can be made using these methods.

See previous information in Cutting section, pages 3 and 4.

In the event that you are ever faced with an especially difficult problem and would like to consult with DuPont, we.d be glad to hear trom you.

We maintain a full-service composite cutting and machining laboratory at our Chestnut Run Plaza site in Wilmington, Delaware. Dur scientists, machinists and technicians

work with composites reinforced with KEVlAR" brand fiber on a daily basis and are continuously searching for new and improved cutting and machining methods.

We are eager to share our knowledge with you in the hope that it will make your experience with KEVlAR" as problem-free as possible.

We welcome your questions and comments and look forward to hearing from you

Call 1-800-4 KEVLAR.