Choose a material for flame-retardant parts

Electrical enclosures, battery housings, vehicle interiors and aircraft cabin parts often need to resist burning. In these uses, flame retardancy is not a nice extra. It is usually a requirement written into a standard or a customer specification.

What fails

• Sustained burning. Most plastics keep burning once lit. Flame-retardant grades are formulated to put themselves out.
• Flaming drips. Burning droplets can set fire to things below the part.
• Thin walls. Ratings are tied to a tested thickness. Thinner walls can burn where thicker ones do not.
• Smoke and toxicity. Transport interiors often have limits on smoke and heat release, not only on burning.

Which properties matter

The most common rating is UL 94. In short, a flame is applied to a test bar and the lab records how quickly it goes out and whether it drips.

Read three things on every rating:

• Thickness. “V-0 at 3 mm” says nothing about a 1 mm wall.
• Who tested it. A datasheet result is not the same as a listed UL certification. Some ratings apply only to the base resin, not to the printed filament.
• The specimen. Most tests use moulded bars. Printed parts with layer gaps and infill can behave differently.

Check heat deflection temperature too. Electrical parts often run warm, and flame-retardant additives can lower some mechanical properties, so check impact strength. For live electrical parts, dielectric strength matters.

Material families that usually work

• PEI and PPSU are inherently flame-resistant and are widely used in aerospace interiors.
• PPS and PEKK also resist burning without heavy additives.
• Flame-retardant PC, PC/ABS and ABS grades are common for electrical enclosures.
• Flame-retardant nylons and resins are available, but there are fewer of them.

Process considerations

We list 31 flame-retardant filaments and 4 flame-retardant resins. FFF offers the most choice, especially in high-performance polymers that need a heated chamber. Resin parts are dense and isotropic, which can help consistency. Whatever the process, the printed part is not automatically covered by the material’s rating.

Design and post-processing tips

• Print solid, or close to it, where fire performance matters. Sparse infill adds air and surface area.
• Match or exceed the rated thickness in your walls.
• Do not dilute it. Mixing in non-FR supports, coatings or paints can change the result.
• Test the finished part to the standard your application requires, with an accredited lab when compliance is needed.

A shortlist from our data

We flag 37 materials as flame-retardant. These have the highest heat deflection temperature:

Open each material to see the exact rating, the tested thickness and whether it is a datasheet value or a listed certification.

1. PC 3107–137
2. PPS 390–133
3. PEKK 3139–182
4. PEI 6153–215.12
5. PPSU 3190–211

Bar = lowest to highest, dot = median. 18 materials, live from our database.

Common mistakes

• Quoting V-0 without the thickness.
• Treating a base resin rating as a printed-part certification.
• Using a sparse-infill part in a fire-rated application.
• Assuming UL 94 satisfies aerospace or rail rules.

See all flame-retardant materials 37 materials