Carbon fiber, fiberglass or kevlar: differences and when to use each.
Short answer: carbon when stiffness at minimum weight comes first; fiberglass when price comes first; kevlar when impact or abrasion comes first. And often the best part combines two of them.
Carbodynamic engineering team · Published on
Quick comparison
Qualitative values for a typical epoxy laminate; every fabric and every manufacturer has its own datasheets.
| Carbon fiber | Fiberglass | Kevlar (aramid) | |
|---|---|---|---|
| Stiffness | Very high | Medium | Medium–high |
| Weight | Very low | Higher | Very low |
| Impact resistance | Medium (brittle failure) | Good | Excellent |
| Price | High | Low | High |
| Machining | Abrasive, cuts well | Abrasive, cuts well | Difficult: frays |
| Electrical conductivity | Conductive | Insulating | Insulating |
| Exposed appearance | Highly valued | Usually painted | Golden yellow |
When to choose each one
- Carbon fiber: lightweight structural parts, visible parts, aerospace, motorsport, drones, orthoses, high-speed machinery.
- Fiberglass: fairings, enclosures, covers, molds and parts where price matters more than weight; also when you need electrical insulation or radio-frequency transparency.
- Kevlar: protective parts, areas exposed to impact or abrasion, parts that must not splinter.
Hybrid laminates
Combining fibers lets you put each material where it performs best: carbon for stiffness, kevlar on the impact-exposed face, fiberglass to lower the cost of intermediate plies or to galvanically isolate carbon from aluminum. We design the laminate with you according to how the part will be used.
We work with carbon fiber, fiberglass, kevlar and other composite materials, with resins formulated to meet the thermal and mechanical requirements of each project.
Composite lamination
Carbon fiber, fiberglass and Kevlar composite parts: CNC-machined molds, prepreg, infusion, RTM, a 200 °C curing oven and FARO inspection. Alicante, Spain.
TechnologiesPrepreg and autoclave
3 × 8 m autoclave being commissioned, available per project; today we cure prepreg in an oven.
TechnologiesHand lay-up
Prototypes, one-off parts and complex geometries.
Technical articlesPrepreg, infusion or RTM
A practical comparison to choose the process by part, run size and budget.
Send us your drawing or 3D model, and we’ll bring it to life.
We study your project with the same care you put into designing it, then send you a clear proposal covering process, lead time and price. Only have the physical part? We’ll scan it and take it from there.
What customers ask us most.
Is carbon fiber stronger than fiberglass?
It is much stiffer and somewhat stronger at far lower weight. Fiberglass handles some impacts better and is considerably cheaper.
Can kevlar be machined?
Yes, but with specific tools and parameters, because it tends to fray instead of cutting cleanly.
Why is carbon isolated from aluminum?
Because in the presence of moisture, galvanic corrosion occurs in the aluminum. A fiberglass layer between the two prevents it.