The lightweight crystalline polymer Kevlar has an extensive range of industrial and consumer applications where the strength and flexibility of the aramid fibre can provide protection for military and law enforcement personnel in the form of body armour, bulletproof vests, helmets and heat-resistant gloves. Additionally, the fibres and pulp of Kevlar can help improve the performance of automotive and aerospace components, as well as reinforce fibre optics, ropes and cables, sealants and adhesives. When cutting Kevlar, experiment with various tools to see which works best with your particular composite material.
- Skill level:
Things you need
- Clean sharp tools
- Respirator or exhaust system
- Lucite acrylic sheets, aluminium, wood or cardboard
- Masking tape or double-faced tape
Use a lathe to cut rods and tubes reinforced with Kevlar. One type of lathe incorporates a tungsten carbide insert which is ground by a diamond wheel to provide a sharp cutting edge that is brazed to a steel shank. Use the lathe at speeds of 75 to 150 surface meters per minute (SMPM) at feeds of 0.04 to 0.06 millimetres per revolution to produce cuts of 0.25 to 0.50 millimetres.
Cut filament wound tubes made of Kevlar with a parting tool. Sand down the edge created by the parting tool for a smoother finish. Although the edge will not be as precise as the edge that can be produced from sawing, this tool is more economical. The parting tool also uses tungsten carbide but lasts for only around 300 cuts at 320 revolutions per minute.
Employ a cast cutter for cutting composites made of Kevlar. Use 2- or 2-1/2-inch titanium-nitride coated blades on this electrical power tool, which cuts by high-speed oscillation rather than blade rotation and is therefore safe to use even when it comes in contact with the skin. However, be sure to use sharp blades as dull blades can cause injury. Also, tighten the retaining nut of the blade and clean the blade before each use. Do not apply too much pressure on the blade or it could break. The edge should be smooth and not require additional finishing.
Sever thin Kevlar composites (1/8 inch or less) or any contoured composites with a rotating disk cutter . For pneumatic rotating disk cutters, run at full speed (at 20,000rpm or 12,000rpm minimum for electric types) and with an air supply of 40.8 to 45.4 Kilogram per square inch. Also, use a fibreglass-reinforced grinding wheel with a diameter of 3 inches and thickness of .035 inch. To facilitate cutting, clamp the material to lessen the vibrations and back both sides with backing material such as acrylic sheets or just masking tape.
Utilise a laser cutter for quick cutting of Kevlar composites of up to 3/16 inch. You will notice that the edge will char, but you can easily correct this with a common pink pearl eraser. The edge will burn but not delaminate, so a secondary finishing step will not be necessary. When laser cutting Kevlar, employ a good exhaust system to divert the toxic smoke that is produced. Do not recirculate the air unless it has been purified, for example, by filtering it through activated charcoal.
Tips and warnings
- For ease in cutting, cut in the direction of the fibres, rather than across the fibres.
- Wear a respirator approved by the National Institute for Occupational Safety and Health or use an exhaust system to avoid inhaling the dust generated from the cutting of Kevlar.
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