If you only read one table, read this one — pick by job first, then check the numbers below.
| If Your Part… | Choose | Why |
|---|---|---|
| Mostly carries load along its length | Pultruded carbon tube | Every fiber runs axially — highest stiffness and strength per euro, by far |
| Bends and twists at the same time | Roll-wrapped carbon tube | Multi-angle laminate carries bending, torsion and hoop load together |
| Needs threads, welding, hard mounting points | Aluminum tube | Metal takes a tap, a weld and a clamp; carbon does not |
| Must stay light above all else | Roll-wrapped carbon tube | Thinnest practical wall with multi-directional strength — best strength-to-weight |
| Cost matters more than performance | Aluminum tube | Lowest unit cost, no tooling, easy to replace anywhere in the world |
| Needs to dissipate heat or conduct electricity | Aluminum tube | Carbon fiber is an insulator — use metal when heat or current must flow |
Carbon fiber is only strong along the fiber. So how the fibers are arranged inside the tube wall decides everything: stiffness, failure mode and price.
A uniform metal alloy. It is isotropic — the same strength in every direction, which is why engineers trust it for unknown or mixed loads. When overloaded it bends and dents before it fails, giving visible warning.
Fiber bundles are pulled through a heated die, so essentially all fibers run along the tube axis. Superb axial stiffness and strength, but little support against crushing forces or torsion — lateral hits tend to split it lengthwise.
Prepreg sheets are wrapped on a mandrel in layers at 0°, ±45° and 90°, then cured under pressure. Each layer handles a different load: axial bending, torsion and hoop strength. Slower to make, better in every direction.
Typical figures for commonly used grades. Exact values depend on layup, wall thickness and diameter — ask us for a datasheet on a specific size.
| Property | Aluminum 6061-T6 | Pultruded Carbon | Roll-Wrapped Carbon |
|---|---|---|---|
| Density | 2.70 g/cm³ | ~1.55 g/cm³ | ~1.55 g/cm³ |
| Elastic modulus | 69 GPa | 120+ GPa (axial) | 70–120 GPa (by layup) |
| Tensile strength | ~310 MPa | Very high (axial) | High, multi-directional |
| Load direction | Same in all directions | Axial only, really | Axial + torsional + hoop |
| Impact behaviour | Dents, warns before failure | Brittle, can split | Tougher, layers arrest cracks |
| Fatigue life | Limited by notches | Excellent under axial cycling | Excellent with correct layup |
| Thermal / electrical | Conductive both | Insulating (except interlayer) | Insulating (except interlayer) |
| Machining & joining | Drill, tap, weld, cut easily | Cut & bond; frays at cut ends | Cut & bond; best dimensional accuracy |
| Unit cost | Low | Medium | Higher |
Pneumatic and hydraulic cylinder barrels, machine frames and guarding, heat-sink and heat-exchanger parts, low-cost prototypes and DIY builds — anything that needs welding, threading or off-the-shelf hardware.
Linear rails and lightweight shafts, telescoping poles, camera tripod legs, tent and kite spars, budget UAV arms, truss members and bracing — parts whose load is clearly axial tension or compression.
FPV racing drone arms, robot and cobot links, CNC gantry beams, bicycle frames and seat posts, golf shafts, fishing rods, carbon camera jibs and gimbal handles — anything that bends and twists while staying light.
For parts that must absorb abuse, we often combine a carbon tube with aluminium end fittings, bonded inserts or sleeve clamps. You keep the weight saving in the span, and the metal takes the concentrated loads at the joints.
A pultruded tube is pulled through a heated die so nearly all fibers run along the tube axis, giving very high axial stiffness at low cost but little crushing or torsional strength. A roll-wrapped tube is made from layers of prepreg wrapped at 0, ±45 and 90 degrees, so it carries bending, torsion and hoop loads together. Roll-wrapped costs more but suits complex or multi-directional loads.
No. Carbon fiber wins on weight-specific stiffness and fatigue life, and will not corrode. Aluminum still wins when you need threads, welds, hard mounting points, heat dissipation, electrical conductivity or the lowest unit cost, and when the part may be dented in service.
We do not recommend it. Threads cut into a thin carbon wall strip easily and bolts clamped directly against the tube can crush it. The standard solutions are bonded metal inserts, split clamps, sleeve joints or structural adhesive. Design the joint around the composite rather than reusing an aluminum detail.
Carbon fiber composite density is around 1.55 g/cm³ versus 2.70 g/cm³ for aluminum, roughly 40% less for the same volume. Because carbon also carries more load per unit weight, real-world replacements often end up 40% to 60% lighter for equal stiffness.
Use roll-wrapped. Drone arms and robot links see bending plus torsion plus crash loads at the same time, exactly the condition a unidirectional pultruded tube handles worst. The multi-angle laminate resists splitting and gives better crash survivability.
Carbon fiber conducts along the fibers, and the epoxy matrix does not conduct at all, so overall a carbon tube is far less conductive than aluminum and is effectively an insulator in most designs. Do not rely on it for grounding or heat sinking, and remember it can be galvanically aggressive when bolted directly to metal.
Yes, and it is often the best answer: use the carbon tube for the spanning section to save weight, and aluminum or bonded inserts at the joints where concentrated loads appear. Isolate the two materials with a barrier layer or adhesive film to avoid galvanic corrosion.
