Ii I - DuPont USA | Global Headquarters · edges will fuzz, requiring secondary edge finishing to *KEVlAR is a DuPont registered trademark. n,lL.. I '-D-/Ii 'I

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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 will beless difficult than cutting across the fibers.

.Cutting and machining composites containing KEVLAR@can create a fine fibrous dust (fibrils) 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 (NIOSH).

.Because of its high tensile strength, KEVLAR@ is tough tocut. It's best to pre-load the fibers in tension while simulta-neously cutting them in a shearing action. This principleespecially applies to machining composites reinforcedwith KEVLAR@.

clean them up. To minimize vibrations, support or clampthe composite as close as possible to the cutting tool.

.Backing the composite with materials such as lucite@acrylic sheet lor equivalentl, aluminum, wood, or evencardboard before machining lespecially drillingl willimprove quality by helping to keep tension on the fibers asthey are cut. Backing acts as a close-tolerance, exit-side

bushing. Ordinary masking tape or painting the compositewith a good primer will also work in many cases. Backboth sides of the composite if possible. You can usePeramacel P-O2 double-faced tape to attach backing tothe composite.

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

.Before beginning, it's always advisable to experiment with

tools and procedures to evaluate which work best with

your composite..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

*KEVlAR is a DuPont registered trademark.

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Use a tool that has been specifically designed for advancedcomposite materials, a tool with a tooth geometry thatproduces a unique shearing action on the outermost fibersto cut a clean, fuzz-free hole without delamination ormushrooming. With composites containing KEVLAR@ brandfiber, a tool of this type causes very little fiber deflection andrequires minimum power and thrust. In turn, it produces lessheat, which allows for a faster cutting speed. Also, it freelyexpels the center plug at the completion of the cut.

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PI y Cutter ]

With its special rakes and angles, this tool is designed for

cutting 25-500 mm holes in thicker composites, that is, from

.5" up to 2.0" thick. The cutters simulate the brads on the brad

point drill and work well with composites containing

KEVLAR@. Use the tungsten carbide type and remember that

a pilot is required. The pilot is either a drill or a bar. It will

help stabilize the drilling operation.

Tips:.For better quality, always back the material.

.Tools are available with arbors and adapters for specific

applications.

During use Idrill press or portable drill), the tool must be

placed so that its cutting edge lies in a position that causes

the composite's fibers to be pulled toward the middle of the

hole. If, however, you want the plug, then the tool bit orienta-

tion is reversed. In either case, fuzzing is kept to a minimum

because the fibers will remain in tension during cutting.

For better cutting, it's important that the tool is kept sharp..For longer life, use a tool with tungsten carbide cutting

teeth and an alloy steel drive body. Cutting speeds:

25 mm diameter 200 RPM.For hand-held operations, use a pilot pin to pick up center

location. 50mm 200 RPM

.Speed: 150-300 SFPM. Feed: 0.13--{J.25 mm/rev. 100 RPM100 mm

.If possible, experiment first to determine the best feed and

speed rates for your particular composite.70 RPM150 mm

50 RPM200 mm

35 RPM300 mm

30 RPMMorris Tool Ltd.

3922 N. Saginaw Street

Flint, MI 48505

(810) 787-7641

Snap-On Tools

1330 Enterprise Dr.

West Chester, PA 19380

1-800-926-5544

400 mm

500 mm 25 RPM

If possible, experiment first to determine the feed and speed

rates that work best with your particular composite.

Vendor (special order}:

International Carbide Corp.

3058 Creek Street Northeast

Yelm, WA 98597-9421

1-800-422-8665

Vendors:

International Carbide Corp.

3058 Creek Street Northeast

Yelm, WA 98597-9421

1-800-422-8665

Pen Associates

P.O.8ox812

201 Pine Knoll Circle

Hockessin, Of 19707

(302) 239-6866

Tips:.Wear-resistant coatings are available.

.Microstop tooling is required to control penetration,

.Resin-Iean composites will be difficult to countersink.

.Operate between 50 and 250 RPM with a feed rate of 0.3mm per revolution. Generally, when countersinking, it'sbest to work at a slow RPM speed while getting in and outof the composite as quickly as possible.

Many conventional radial cutting edge countersinks (1,2,3,or 4 flute HSS types; full carbide types; carbide-tipped types;and polycrystalline diamond insert types) produce good toexcellent results with one exception-they all cause fuzzingaround the perimeter of the countersunk hole. Only usesuch countersinks on composites made with KEVLAR@ if (1 )fuzzing is acceptable or, (2) secondary finishing can improvethe initial result. Also, if the composite has a surface plyof glass over its KEVLAR@, conventional countersinks mayproduce acceptable results.

Vendors:

ATI Tools Guhring2425 W Vineyard Ave. 1445 Commerce Ave.Escondido, CA 92029-1222 Brookfield, WI53045(760)-746-8301 (414) 784-6730

International Carbide Corp. Pen Associates, Inc.3058 Creek Street Northeast PO. Box 812Yelm, WA 98597-9421 201 Pine Knoll Circle1-800-422-8665 Hockessin, Of 19707

(302) 239-6866

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For composites containing KEVLAR@, use a carbide-tippedtool with two very sharp flutes and sickle-shaped cuttingedges that are designed to remove chips quickly. A tool ofthis type with a positive rake in the radial direction will

prevent peripheral fulling. One with a slightly positive rakein the axial direction will cut more aggressively and more

smoothly, while one with a slightly negative rake will cut lessaggressively. Depending on your needs, choose the one thatworks best for you.

Holes may be punched into a thin composite of KEVLAR<BJbrand fiber with a punch and die set having very tight toler-ances-.OOO2"-.OOO5" maximum on the diameter. Ideally, thepunch should be made of tungsten carbide and used to sizethe tool steel die. For single piece punches or die boards,use a soft backing material such as aluminum, wood, orlucite@ acrylic sheet lor equivalent) to protect the tool andto ensure a cleanly cut hole.

Vendors:

Progressive Service Die Co.1 T ay/or B/vd.New Kingstown, PA 17072(717) 766-8004

Snap-On Tools1330 Enterprise Dr.West Chester, PA 193801-800-926-5544

See information in Cutting section of the "Machining-cutting, drilling and sawing" brochure.

For composites made with KEVLAR@, use a tungsten carbide,

split helix router bit with either two or four helixes. You'll get

better results with the four helix type. When combined with

a sickle-shaped drill point, this router tool will easily enter

the composite.

Operating speed should be between 20,000 and 27,000 RPM,Use a 1/4" bit for pin router tables; a 1/2" bit for controlledrouting machines. Additional sizes are available.

You'll get better results if you limit the finish cuts to a radialdepth-of-cut of one quarter of the cutter diameter or 0.06"-whichever is less. This eliminates the excessive delamina.tion that is caused by heavier cuts.

For the vertical cut Isidewalls of the counterbore), use atool with two curved, sickle-shaped cutting edges-similarto the brad point drill. For the horizontal cut Ibase of thecounterbore), use a tool with two straight radial cuttingedges with a slightly negative rake.

Tools should be tungsten carbide type and kept very sharp.Also, the tool design should include a 0.05 mm differencebetween the peripheral and the radial cutting edge, with theperipheral cutting edge leading the radial. These tools areusually custom designed for specific hole configurationsand they work well with composites containing KEVLAR@brand fiber.

Tips:.To minimize the vibrations and maximize the quality,

remember to clamp the composite.

.A template or a guide system is recommended,

.The router bit must turn in the cutting direction, and it

must be kept clean and sharp.Tips:.Speed: Low, between 50-100 RPM

(depending on the materialj.

.Avoid climb cutting,

.Resin-rich composites are more easily routed thanresin-Iean ones. If the composite is less than 40% resin,routing will be difficult.

.Feed: Slow Idepending on the materiall.

.Tool with pilot must fit tightly in pre-drilled hole..For best results back the composite with masking tape,

Lucite@ acrylic sheet (or equivalent), aluminum or wood.Back both sides if possible.

.For hand-held operations, microstop is required.

Vendors:

Guhring1445 Commerce Ave.

Brookfield, WI53045

(414) 784-6730

Pen Associates, Inc.

P.O. Box 812

201 Pine Knoll Circle

Hockessin, Of 19707

(302) 239-6866

After routing, some secondary edge finishing may be

necessary.

Vendors:

Guhring International Carbide Corp.1445 Commerce Ave. 305B Creek Street Nottheast

Brookfield, WI53045 Yelm, WA 98597-9421

(414) 784-6730 1-800-422-8665

Pen Associates, Inc.

P.O. Box 812

201 Pine Knoll Circle

Hockessin, Of 19707

(302) 239-6866

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Conventional straight flute routers, diamond pattern routers,and opposed helical routers as used with metals, glass orcarbon fiber composites are notrecommended for compos-ites containing KEVLAR@. They will cause excessive fiberfulling or edge delamination. However, if for any reason youmust use one of these types, be sure to back the compositebefore routing. This will help minimize the fulling and

secondary finishing.

Use this type of router for composites made with KEVLAR@brand fiber if they are less than 1.5 mm 1.060") thick. Therouter bit consists of a cutting spiral that operates within ashear bushing. The bit and shear bushing are installed in aspecial nose piece which has a guiding device for cuttingalong a template. The entire assembly fits into a pneumatichand-held motor with variable speeds of 700 to 2,500 RPM.

lips:.For the best edge quality, use a template.

.Operating speed should be at least 2,000 RPM.

.Determine the feed rate by experimenting on a sample of

the composite.

.For best results, back the composite, both sides if possible.

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For composites reinforced with KEVLAR@, use the following

procedure:

1. Holding the hand sander at an approximate 45° angleto the composite edge, sand the fibers in towards themiddle of the edge.

2. Sand the opposite side of the edge in the same manner,being sure to maintain an approximate 45° angle.

3. Now, change the angle of the sander to approximately90° and go straight at the edge-the point where the two45° angles converge. Move the sander crosswise toshear off all the exposed fiber ends. Be careful not tosand too deep, for if you do, you'll pull the fibers out andhave to start allover again.

If you are working with a stationary belt sander, theprinciple is the same.

lips:.Forthe best results, use 80 to 180 grit aluminum oxide or

silicon carbide sanding belts.

.It's always a good idea to experiment first with differentsanding belts to determine which work best with your

particular composite.

.Because of resin accumulation Iblinding), disk sanding isnot recommended. Melted resin will gum-up the edge ofthe disk.

For a high quality edge finish, hand sand your compositewith 240 grit wet/dry abrasive paper and water. For an even,superior finish, vary the grades by working up to 600 gritpaper. Be sure to use water. It will act as a coolant andlubricant, and it will help prevent you from cutting toodeeply into the fibers.

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

Dynabrade Inc.8989 Sheridan DriveClarence, NY 14031(716) 631-0100

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DuPont Engineering Fibres

P.O. Box 50

CH-1218Le Grand-Saconnex

Geneva, Switzerland

Tel: ++41-22-7175111

Fax: ++41-22-7176021

Address Listings for Literature-KEVLAR" 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

DuPont Toray Company, Inc.

1-5-6 Nihombashi-Honcho,

Chuo-ku, Tokyo 103

JapanTel: 81-3-3245-5080

Fax: 81-3-3242-3183

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-62647-12

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 from 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 forvvard to hearing from you.

Call 1-800-4 KEVLAR.