Kevlar
also AFRP
Kevlar laminate is a para-aramid (PPTA) fibre composite, usually epoxy-matrix, supplied as woven fabric, prepreg and filament-wound forms, with vinyl ester, phenolic and thermoplastic matrix variants on file.
Values for the Epoxy Matrix condition
Kevlar grades and fills
Kevlar is supplied in 7 conditions, soft to hard. Epoxy Matrix is the default FabDigit quotes; the values on this page are for it.
Compare all 7 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
aramid/phenolic honeycomb & interior laminate | Aircraft interiors, ducting and Nomex-type honeycomb faces where FAR 25.853 fire/smoke/toxicity and V-0 rating dominate over strength. | 450 | 1.5 | 88 Shore D | |
aramid/PA or PP organosheet | Stampable, weldable and re-formable aramid composite for high-rate parts and impact liners; lower stiffness and creep resistance than epoxy. | 450 | 2.5 | 78 Shore D | |
epoxy laminate | Carbon supplies compressive strength and stiffness while aramid supplies damage tolerance — the usual fix for AFRP's weak compression. | 800 | 1.3 | 88 Shore D | |
Kevlar 29 reinforcement | Pick for armour, ballistic panels and ropes where energy absorption matters more than stiffness. | 1,150 | 3.4 | 85 Shore D | |
aramid/VE laminate | Marine and corrosion service: cheaper wet-layup/infusion than epoxy, better hydrolysis resistance than polyester, slightly weaker bond to aramid. | 1,150 | 1.7 | 85 Shore D | |
Kevlar 149 reinforcement | Use where maximum specific stiffness and lowest moisture pickup are required (antennas, precision structures); most expensive and least tough. | 1,250 | 1.3 | 88 Shore D | |
Epoxy MatrixDefault Kevlar 49 / epoxy laminate (UD, Vf ≈ 60 %) | Default structural aramid composite: best stiffness/strength and adhesion, for aerospace panels, filament-wound vessels and marine hulls up to ~120 °C. | 1,350 | 1.8 |
Supply forms, finishes and certifications
Ways Kevlar is supplied — form, process route, surface or paperwork — without a datasheet of their own. A reinforced fill changes stiffness and elongation; the branded products above carry the filled values.
| Option | What it is | Type |
|---|---|---|
Woven Fabric | Woven fabric laminate | Reinforcement |
What is Kevlar?
Kevlar laminate is a para-aramid (PPTA) fibre composite, usually epoxy-matrix, supplied as woven fabric, prepreg and filament-wound forms, with vinyl ester, phenolic and thermoplastic matrix variants on file. At 1.38 g/cm³, 1350 MPa tensile strength, 76 GPa modulus and 1.8 % elongation it gives high specific strength with ballistic, impact and fatigue resistance and a negative fibre-direction CTE. Compressive and flexural strength are far below tensile strength because the fibres microbuckle; moisture uptake and UV ageing are significant, service is capped near 120 °C, and cutting causes fuzzing. Carbon/epoxy suits compression- or stiffness-driven parts. Kevlar has a density of 1.38 g/cm³ (0.0499 lb/in³), lighter than 66% of composite grades. Its glass-transition temperature is 135°C (275 °F). Kevlar has a tensile strength of 1,350 MPa (196 ksi), stronger than 73% of composite grades. Elongation at break is 1.8% and the elastic modulus is 76 GPa (11 Msi).
What is Kevlar used for?
- Body armor
- Ballistic panels
- Aerospace interior and secondary structure panels
- Filament-wound pressure vessel overwraps
- Boat hulls and impact skins
- Sports equipment shells
- Impact-resistant skid plates and guards
Advantages
- Tough — resists crack growth — 35 MPa·√m (31.9 ksi·√in), better than 91% of composite grades
Limitations
- Degrades in UV without stabilisers — 25/100, worse than 86% of composite grades
- Limited service temperature — 120°C (248 °F), worse than 78% of composite grades
- Difficult to machine — 20/100, worse than 77% of composite grades
Kevlar properties
Typical room-temperature values for Kevlar-Epoxy Matrix; bars are the position among composite grades.
Physical4
Kevlar has a density of 1.38 g/cm³ (0.0499 lb/in³), lighter than 66% of composite grades. Its glass-transition temperature is 135°C (275 °F).
Mechanical12
Kevlar has a tensile strength of 1,350 MPa (196 ksi), stronger than 73% of composite grades. Elongation at break is 1.8% and the elastic modulus is 76 GPa (11 Msi).
Thermal9
Kevlar is rated for continuous service to 120°C (248 °F). It conducts heat at 0.5 W/m·K (0.289 BTU/hr·ft·°F), better than 56% of composite grades. Thermal expansion is -2 µm/m·K (-1.11 µin/in·°F).
Electrical5
Kevlar is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 54% of composite grades. UV resistance is poor.
Sustainability3
Producing a kilogram of Kevlar takes about 250 MJ of energy and emits 14 kg of CO₂ — more than 54% of composite grades. Typical recycled content is 0%.
Manufacturability2
Kevlar's machinability is poor (20/100, worse than 77% of composite grades).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the composite family
Yield strength against density for every composite grade FabDigit runs. Kevlar is highlighted; hover a dot for its name, or open the interactive family chart.
Working with Kevlar
Is Kevlar easy to machine?
Fibers do not cut cleanly — use sharp carbide/PCD shear-angle or serrated 'Kevlar' router bits, back-up plates, or waterjet/laser trimming to avoid fuzzing and delamination.
Can Kevlar be welded?
Thermoset epoxy laminates cannot be welded; join by secondary bonding with film/paste adhesive or bolted joints with bushed holes (thermoplastic-matrix variants can be resistance or ultrasonic welded).
Can Kevlar be formed, bent or molded?
Processed as prepreg autoclave/oven cure (120–180 °C), resin infusion/RTM, wet layup or filament winding; aramid fabric drapes well but must be dried before cure to avoid moisture-induced porosity.
Manufacturability
The process limits FabDigit's quote engine applies to Kevlar. Design inside these and the part quotes instantly; outside them it routes to an engineer.
CNC machining
| Machinability | Poor20 / 100 |
|---|---|
| Cutting speed (rough / finish) | — / — |
| Minimum wall | — |
| Minimum internal radius | — |
| Drill depth limit | |
| Best surface (machined / polished) | Ra — / — |
| Hardenable after machining | — |
Sheet metal
| Formability | Not Recommend5 / 100 |
|---|---|
| Weldability | Not Recommend5 / 100 |
Kevlar chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| para-aramid fiber (PPTA, poly-p-phenylenfiber volume fraction ≈ 55–62 % for prepreg laminates | 50 – 65 | 60 |
| sizing / finishfiber surface treatment for adhesion | 0.1 – 1 | 0.5 |
| epoxy resin (DGEBA / amine or dicyandiammatrix; substituted by vinyl ester, phenolic or thermoplastic in other variants | ≥ 35 (balance) |
What surface finishes work on Kevlar?
Cut edges must be sealed with resin or edge tape; paint or gel-coat with UV-blocking pigment is essentially mandatory for outdoor service, and surfacing film gives a smooth paintable skin.
Surface treatments FabDigit runs on composite parts — pick them in the quote configurator or call them out on the drawing. Each links to its datasheet in the surface-finish library (thickness, specs, call-out, material verdicts).
Organic Coating
Equivalent designations
Standards and trade names that resolve to Kevlar in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- AFRP
How much does Kevlar cost?
Kevlar is a premium-cost composite ($$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Kevlar — frequently asked
What is Kevlar used for?
Kevlar is typically used for body armor, ballistic panels, aerospace interior and secondary structure panels, filament-wound pressure vessel overwraps, boat hulls and impact skins and sports equipment shells. In short: aramid impact laminate.
What is the tensile strength of Kevlar?
Kevlar has a typical tensile strength of 1,350 MPa (196 ksi) — stronger than 73% of composite grades. Strength varies by condition: see the 7 listed tempers.
Is Kevlar easy to machine?
Not especially — machinability is rated poor (20/100, worse than 77% of composite grades). Fibers do not cut cleanly — use sharp carbide/PCD shear-angle or serrated 'Kevlar' router bits, back-up plates, or waterjet/laser trimming to avoid fuzzing and delamination.
Can Kevlar be welded?
Thermoset epoxy laminates cannot be welded; join by secondary bonding with film/paste adhesive or bolted joints with bushed holes (thermoplastic-matrix variants can be resistance or ultrasonic welded).
What surface finishes work on Kevlar?
Cut edges must be sealed with resin or edge tape; paint or gel-coat with UV-blocking pigment is essentially mandatory for outdoor service, and surfacing film gives a smooth paintable skin.
Can Kevlar be formed, bent or molded?
Processed as prepreg autoclave/oven cure (120–180 °C), resin infusion/RTM, wet layup or filament winding; aramid fabric drapes well but must be dried before cure to avoid moisture-induced porosity.
What is the maximum service temperature of Kevlar?
Kevlar is rated for continuous use to about 120°C (248 °F), and briefly to 200°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does Kevlar cost?
Kevlar is a premium-cost composite ($$$), pricier than about 58% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in Kevlar?
Yes — Kevlar is available for CNC machining and sheet metal with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Kevlar Aramid Fiber Technical Guide — DuPont (2017)
- ASM Handbook Vol. 21 — Composites — ASM International (2001)
- CMH-17 (MIL-HDBK-17) Composite Materials Handbook, Vol. 3 Polymer Matrix Composites — SAE International / CMH-17 (2012)
- Aramid fabric prepreg datasheets — Hexcel / Toray Advanced Composites (2022)
- CES EduPack material data — aramid fiber reinforced epoxy — Granta/Ansys (2021)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.