Fiberglass, carbon fiber, and Kevlar are the three primary reinforcement fibers used in industrial composite materials. Each offers distinct properties for different applications. Machs FRP manufactures fiberglass and carbon fiber composite products for demanding industrial use.
Three Key Reinforcement Fibers
The fiber reinforcement determines the mechanical properties of a composite material. The Wikipedia article on fiber-reinforced composites explains how fiber type affects performance. Selecting the right fiber depends on strength requirements, stiffness needs, weight constraints, budget, and environmental exposure.
Fiberglass
Fiberglass is the most widely used reinforcement fiber, offering excellent value for general industrial applications: E-glass (electrical grade) is the standard type — tensile strength 500 ksi, modulus 10.5 msi. S-glass offers 30% higher strength for premium applications. Fiberglass provides good corrosion resistance, electrical insulation, and impact resistance. Cost is significantly lower than carbon or Kevlar. Fiberglass composites are the default choice for most industrial FRP products when extreme performance is not required. Machs FRP’s standard FRP profiles use E-glass fiber for excellent general performance at competitive pricing.
Carbon Fiber
Carbon fiber offers the highest stiffness and strength-to-weight ratio of any reinforcement fiber. Standard modulus: 33-40 msi (3x fiberglass). High modulus: 50-70 msi. Tensile strength: 350-700 ksi. Carbon fiber is 2-3x stiffer and 5x stronger per unit weight than steel. However, it is 5-10x more expensive than fiberglass. Carbon fiber is electrically conductive (unlike fiberglass and Kevlar). It has low impact resistance and can fail catastrophically. Used in aerospace, high-performance automotive, sporting goods, and industrial robotics.
Kevlar (Aramid)
Kevlar (para-aramid fiber) is known for exceptional impact and ballistic resistance. Tensile strength: 400-500 ksi. Modulus: 18-19 msi (between fiberglass and carbon). Kevlar is lightweight, flame-resistant, and cut-resistant. It has poor compressive strength — it performs better in tension. Kevlar is difficult to cut and machine. It absorbs moisture (up to 7%). Used in ballistic protection, cut-resistant gloves, tires, marine composites, and high-impact industrial components.
Strength Comparison
| Property | Fiberglass (E) | Carbon (Std) | Kevlar 49 |
|---|---|---|---|
| Tensile strength (ksi) | 500 | 500-700 | 400-500 |
| Compressive strength | Good | Excellent | Poor |
| Impact resistance | Good | Fair | Excellent |
| Fatigue resistance | Good | Excellent | Good |
Stiffness and Modulus
Carbon fiber modulus (33-70 msi) is 3-6x stiffer than fiberglass (10.5 msi). Kevlar (18 msi) is between them. For deflection-critical applications where stiffness is the primary requirement, carbon fiber is the best choice. For strength-critical applications where deflection is less important, fiberglass often provides better value. Kevlar’s moderate stiffness combined with excellent toughness makes it ideal for impact-resistant structures.
Weight Comparison
Density: Fiberglass 2.55 g/cm³, Carbon fiber 1.75 g/cm³, Kevlar 1.44 g/cm³. All three fibers are lighter than steel (7.8 g/cm³) and aluminum (2.7 g/cm³). Carbon fiber offers the best strength-to-weight ratio. Kevlar offers the best toughness-to-weight ratio. Fiberglass offers the best cost-to-strength ratio. For weight-critical applications, carbon fiber or Kevlar may justify their higher cost.
Cost Comparison
Fiberglass (E-glass): $2-5 per pound. Carbon fiber (standard): $15-40 per pound. Carbon fiber (aerospace grade): $50-200 per pound. Kevlar: $20-40 per pound. For most industrial applications, fiberglass provides the best balance of performance and cost. Carbon fiber is specified only when its higher stiffness or weight savings justify the premium. Kevlar is specified for impact or ballistic requirements.
Industrial Applications
Fiberglass: FRP grating and profiles, chemical storage tanks, piping, boat hulls, automotive panels, wind turbine blades, construction reinforcement. Carbon fiber: Aerospace components, high-speed machinery, robotics arms, race car parts, medical devices, precision instruments. Kevlar: Ballistic armor, cut-resistant gloves, conveyor belts, marine composites, industrial safety equipment. Machs FRP offers custom pultruded profiles in all three fiber types.
Comparison Table
| Factor | Fiberglass | Carbon Fiber | Kevlar |
|---|---|---|---|
| Tensile strength | 500 ksi | 500-700 ksi | 400-500 ksi |
| Modulus | 10.5 msi | 33-70 msi | 18 msi |
| Density | 2.55 g/cm³ | 1.75 g/cm³ | 1.44 g/cm³ |
| Impact resistance | Good | Fair | Excellent |
| Cost per lb | $2-5 | $15-40 | $20-40 |
| Best value | General use | Stiffness-critical | Impact-critical |
FAQ
Which fiber is strongest?
Carbon fiber has the highest tensile strength (500-700 ksi) and stiffness. Kevlar has the best impact resistance. Fiberglass offers the best value for general use.
Is carbon fiber worth the extra cost?
For applications requiring maximum stiffness or minimum weight, yes. For general industrial use where weight is not critical, fiberglass offers better value.
Can fiberglass and carbon fiber be combined?
Yes, hybrid composites using both fibers are common. A carbon fiber layer can provide stiffness while fiberglass layers provide impact resistance at lower cost.
What is the best fiber for impact resistance?
Kevlar has the best impact resistance and is the standard material for ballistic protection and high-impact industrial components.
Multi-Fiber Composite Solutions from Machs
Machs FRP manufactures fiberglass, carbon fiber, and hybrid composite products for industrial applications. Browse our product range or contact our engineering team for material selection assistance.
