PAHT-CF vs aluminium 7075-T6: a technical deep dive
For decades the standard way to make strong, light parts was to machine them from aluminium (often 6061, or aerospace-grade 7075-T6). With high-temperature polyamides reinforced with chopped carbon fibre (PAHT-CF), that has changed. Let's look at the data.
PAHT-CF (carbon-fibre nylon)
- Density: ~1.15 g/cm³
- Tensile strength: ~130 MPa (Z axis around 70 MPa)
- Heat deflection (HDT): 194 °C (at 0.45 MPa)
- Stiffness (modulus): ~8.5 GPa
- Advantage: Design freedom, no setup time, fast payback, weight.
Aluminium 7075-T6
- Density: 2.81 g/cm³
- Tensile strength: 572 MPa
- Melting point: 477 - 635 °C
- Stiffness (modulus): 71.7 GPa
- Advantage: Maximum strength, fully isotropic.
Strength relative to weight (specific strength)
If your part sees very large linear loads (>500 MPa), aluminium 7075 always wins. There is a reason it is used in aircraft wings. But if we look at thestrength-to-weight ratio, the picture changes. PAHT-CF weighs less than half of aluminium (1.15 g/cm³ vs 2.81 g/cm³). By redesigning a fixture, hollowing it out (infill) and using topology optimisation in CAD, you can get a carbon-fibre part that weighs 70% less than the aluminium original, with enough stiffness for most real applications on a factory floor.
Chemical and thermal stability
Many assume plastic melts in an engine room. PAHT-CF is dimensionally stable up to 194 °C and resists engine oils, coolants and aggressive chemicals that can quickly corrode unprotected metal.