Nylon-FR (PA-FR): density, print temperature and when to choose it
PA-FR (Nylon-FR) is nylon with flame-retardant additives that slow combustion and self-extinguish the material once the flame source is removed, while retaining the base strength and wear resistance of PA12. It's used where a part has to meet fire-safety standards — in electrical, aviation, and public transit applications — not just where a part needs to be strong.
Key properties
| Parameter | Value |
|---|---|
| Density | ≈1.18 g/cm³ |
| Nozzle temperature | 260–280°C |
| Bed temperature | 80–100°C |
| Part cooling | light |
| Shrinkage | noticeable, needs slicer compensation |
| Enclosure required | yes |
When to use it
- Housings and holders for electrical components where a flammability rating (e.g. UL94) is required by regulation.
- Parts for aviation, rail, and public transit with mandatory fire-safety requirements.
- Connectors, wiring covers, and elements near heat sources where plain nylon or ABS won't pass certification.
When to pick something else
- There's no flammability requirement — plain PA12 is cheaper and prints slightly easier at the same mechanical strength.
- You need even higher stiffness with comparable fire resistance — consider reinforced PA6-GF, though note not every PA6-GF grade has FR certification.
- You need fire resistance along with transparency or heat resistance beyond nylon's range — look at PC-FR.
Pros and cons
Pros: self-extinguishing behavior while retaining the base nylon's strength and wear resistance, suitable for certifiable electrical and transportation parts, good chemical resistance.
Cons: highly hygroscopic — requires drying before every print, noticeable shrinkage complicates printing large flat parts, high price, a narrow field of suppliers with confirmed FR certification.
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PA-FR is a premium-priced material due to its certified flame-retardant additives, and cutting costs with an unverified alternative is risky if the part is subject to fire-safety compliance checks — failing certification devalues the whole batch. In your cost calculation, always budget for drying the filament before printing and a higher defect rate on large parts from shrinkage — both are more pronounced with PA-FR than with plain PA12.