Nylon PA12 vs aluminum — when printed nylon replaces machined metal.
For structural brackets, housings, and robotic tooling, the default material choice used to be machined aluminum. For many of those applications, MJF-printed Nylon PA12 Glass Filled is now the better answer — not because it is stronger (it is not), but because it is lighter, cheaper, faster to produce, and supports geometry that would be impossible to machine. This guide walks through the trade-off and helps you decide whether your aluminum part can be replaced.
Detailed comparison
Property-by-property breakdown
| Property | Nylon PA12 GF | Machined Aluminum 6061-T6 |
|---|---|---|
| Tensile strength | 48 MPa | 310 MPa |
| Density | 1.3 g/cm³ | 2.7 g/cm³ |
| Strength-to-weight | Competitive for most loads | Higher absolute strength |
| Heat deflection | 170°C | 400°C+ continuous |
| Electrical conductivity | None (insulator) | Excellent conductor |
| Geometric freedom | Unlimited (undercuts, lattices) | Limited by tool access |
| Typical lead time | 5 business days | 5–10 business days |
| Typical cost per part | $20–$100 | $100–$500 |
| Best for | Lightweight structural, complex geometry | High load, thermal, electrical |
Our recommendation
Switch to Nylon PA12 Glass Filled when: the part does not see sustained high temperatures (above 120°C), does not need to conduct heat or electricity, has complex internal geometry, or needs to be lightweight. Stay with machined aluminum when: the part operates in high heat, must carry electrical current, needs precision under ±0.1mm, or must be compatible with aggressive chemicals that degrade nylon.
FAQ
Frequently asked questions
Can 3D printed nylon replace machined aluminum?
In many cases, yes. Nylon PA12 Glass Filled (1.3 g/cm³) is half the density of aluminum 6061-T6 (2.7 g/cm³) and handles complex geometry that would be impossible to machine. It replaces aluminum for structural brackets, housings, and tooling at lower cost.
What is the strength difference between nylon and aluminum?
Aluminum 6061-T6 has much higher absolute tensile strength (310 MPa vs 48 MPa for PA12). However, the strength-to-weight ratio is competitive for many applications, and nylon handles complex geometry, undercuts, and lattices that aluminum cannot.
When should I keep using aluminum instead of nylon?
Keep aluminum when: the part operates above 120°C continuously, needs to conduct heat or electricity, requires tolerances tighter than ±0.3mm, or must resist aggressive chemicals that degrade nylon.
How much cheaper is 3D printed nylon vs machined aluminum?
Typical cost per part is $20–$100 for MJF nylon vs $100–$500 for machined aluminum, depending on geometry. Nylon also ships in 5 business days vs 5–10 for CNC, and has zero setup cost.
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Choose MJF when volume is under 2,000-5,000 parts, when you need parts in days instead of months, when geometry is complex (undercuts, internal channels), or when your design is still evolving. Choose injection molding when volume exceeds 5,000+ parts of the same geometry and your design is frozen.
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Choose CNC when tolerances are tight (under ±0.05mm), when the geometry is prismatic (blocks, plates, shafts that a mill can easily reach), or when you need a polymer grade like polyacetal, PEEK, or Ultem that is not available in 3D printing. Choose 3D printing when geometry is complex (undercuts, lattices, organic curves, internal channels), when part volume is low, or when turnaround matters more than absolute tolerance.
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Choose PA12 for most production applications — brackets, housings, clips, and structural parts where stiffness and heat resistance matter. Choose PA11 when ductility and impact resistance are priorities — living hinges, snap-fits under repeated cycling, energy-absorbing components, and applications with sustainability requirements.
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