Nozzles for Abrasive Filaments: Carbon Fiber, Glass Fiber, and Glow

Who this guide is for

You've bought, or are thinking about buying, a filament with "CF," "GF," "glow," "sparkle," "marble," or "metal" on the label, and you want to know whether your printer can handle it. This guide explains which filaments manufacturers treat as abrasive, what the common nozzle materials are and how they trade off, and how to find the part that actually fits your machine.

We don't recommend specific nozzle products here, and we make no fit claims for any nozzle. Fit depends on the exact printer model, hotend, and revision, and only the printer or nozzle maker's own documentation can confirm it. Our replacement nozzle guide covers nozzle systems and fit in more depth.

Which filaments count as abrasive?

Manufacturers agree on the core group and differ at the edges.

• Fiber-filled filaments. Prusa's composites guide says "carbon, glass and kevlar fibers are highly abrasive" and that "a hardened steel nozzle is needed." Bambu Lab's filament guide marks a hardened steel nozzle as "Required" for PLA-CF/GF, PETG-CF, ABS-GF, PA-CF/GF, PET-CF/GF, PPA-CF/GF, and PPS-CF/GF.
• Particle-filled filaments. Bambu Lab's nozzle guidance names "PLA Marble, PLA Sparkle, PLA Glow" alongside fiber-filled grades as materials that need a hardened steel nozzle. Its P1S upgrade guide lists carbon fiber, glass fiber, metal-filled, and glow-in-the-dark filaments as abrasive, and explains that the phosphorescent particles in glow filament act "like sandpaper."
• Plastics with additives in general. Prusa's nozzle guide says "most of the abrasive materials are composites and plastics with additives," and that a regular brass nozzle "will degrade quickly and lose its properties" when printing them.

Even one maker's documents don't always line up. Bambu Lab's nozzle table marks PLA Marble and PLA Metal as "Not Required" for a hardened nozzle, while the guidance text below the same table lists PLA Marble among the particle-filled materials that need one, and the P1S guide lists metal-filled filaments as abrasive. When sources disagree, treat the filament as abrasive.

Not abrasive: Bambu Lab's P1S guide describes standard, non-abrasive filaments such as PLA, PETG, ABS, PA (nylon), and TPU as well suited to its stainless steel hotend, and its filament table lists unfilled PLA, PETG, ABS, ASA, PC, and TPU as not requiring a hardened nozzle. If you only print unfilled materials, you don't need a wear-resistant nozzle.

Why the filament maker's word matters most

"CF," "glow," and "sparkle" are not standardized grades. Filler type, particle size, and loading differ from one brand to the next, and a label won't tell you how abrasive a particular spool is. Prusa's advice is simple: "Always ask your filament vendor if you are not sure about filament requirements." Look for a nozzle requirement on the product page or technical data sheet. If the maker says a hardened nozzle is required, believe it, even if a friend printed a spool on brass without trouble.

Nozzle materials and their trade-offs

The table summarizes how manufacturers describe each material. These are general descriptions, not ratings for any particular product, and quality varies between makers.

A few points the table can't capture:

• "Coated" covers very different things. A plated brass nozzle and a coated tool-steel nozzle are not the same part. Read what the base material is and what the maker says it is rated for.
• Wear-resistant doesn't mean wear-proof. E3D says its own coated tool-steel nozzle has wear resistance "orders of magnitude higher than any other E3D nozzle," but also warns that some filaments with aggressive fillers, such as certain filled nylons, "can cause significant wear" even on that nozzle. That's E3D's claim about its own product. The general point holds for every nozzle: abrasives shorten its life.
• Cleaning methods matter for coatings. Prusa's nozzle guide warns that an acupuncture needle or a brass brush can damage a nozzle's coating, and that cold pulls can tear the coating off one of its coated nozzles. Other makers' procedures differ. Bambu Lab's filament guide, for example, recommends heating to 280 °C and cleaning the inside with an Allen key and needle before printing abrasive materials. Follow the cleaning guidance for your specific nozzle.

Thermal differences

Polymaker notes that stainless steel has lower thermal conductivity than brass, and that hardened steel "requires higher nozzle temperatures due to reduced thermal conductivity." Neither Polymaker nor the other sources we checked give a figure for how much to raise the temperature, so we don't either. If you switch nozzle material, start from your filament maker's recommended range, check your printer maker's profile for that nozzle, and watch for signs of under-extrusion.

What nozzle size should you use for filled filaments?

Filled filaments clog more easily, and small nozzles make it worse.

• Bambu Lab: do not use a 0.2 mm nozzle, because "the clogging risk is extremely high." A 0.6 mm hardened nozzle is the "first choice" for lower clogging risk. A 0.4 mm hardened nozzle is the second choice, at 0.15–0.3 mm layers and roughly 100 mm/s maximum. For its own specially designed filled filaments, Bambu Lab recommends 0.4 mm hardened steel as the first choice.
• Prusa: a 0.4 mm nozzle with 0.2 mm layers is the lowest optimal setup for composites. Prusa's nozzle guide says filament for its 0.25 mm nozzle "can not have composite particles like Kevlar, carbon fiber, or glass."
• Bambu Lab P1S guide: hardened steel nozzles for the P1 series aren't available in 0.2 mm.

Prusa also lists the trade-offs of fiber-filled filaments themselves: worse layer-to-layer adhesion, more brittle filament, and a higher risk of clogging. A wear-resistant nozzle doesn't change those properties.

Do abrasive filaments wear more than the nozzle?

Abrasive filament touches everything on its way to the nozzle.

• Extruder gears. Bambu Lab's P1S guide says abrasive particles erode "the inner surfaces of the nozzle and extruder gears over time," and that worn gears can cause filament slippage, under-extrusion, or skipped layers. Its filament guide says that with filled materials "the nozzle and extruder gears require more frequent maintenance." On the P1S, Bambu Lab offers hardened steel extruder gears as well as a hardened hotend.
• Feeders and multi-material systems. Bambu Lab warns that rough or abrasive materials such as carbon fiber or glow filaments "can eventually grind down" the replaceable PTFE feed channels inside its AMS units, and it lists certain brands of filled filaments as too brittle or too rough for its AMS and AMS lite.
• Whole print cores. UltiMaker uses swappable print cores. It says AA cores are for non-abrasive materials, while CC cores are for abrasive composites and are "only compatible with UltiMaker printers with abrasion-resistant feeders," which excludes the UltiMaker 3. Its CC+ core is only compatible with the S6, S8, and Factor 4+.

How to find the right nozzle for your printer

Nozzles are not interchangeable across printers, or even across hotends from the same brand. Our replacement nozzle guide goes into the details. The short version:

1. Identify the exact printer model and hotend. Prusa's nozzle guide, for example, applies to printers with the Nextruder hotend (CORE One family, MK4/MK3.9 series, and XL), not to every Prusa printer. UltiMaker's core compatibility depends on the printer model, as shown above.
2. Start from the printer maker's spare-parts and documentation pages. They list which nozzles or hotend assemblies fit, and in which materials and sizes. Bambu Lab's P1S guide tells owners to choose the hardened parts made "for P1 Series."
3. Check whether you're replacing a nozzle or a whole hotend. On some printers the nozzle is a separate part. On others, such as the Bambu Lab P1S in its upgrade guide, you can buy the hardened nozzle on its own or a complete hotend assembly. For examples, see our comparisons of the Bambu A1 hardened steel and stainless steel hotends, E3D ObXidian and brass Prusa Nextruder nozzles, and Creality's Unicorn and E3D's ObXidian Unicorn.
4. Match the filament's stated requirement. Confirm the nozzle material is one the filament maker accepts and the diameter is one both makers recommend.
5. Tell the printer and slicer what's installed. Bambu Lab's P1S guide has you select the installed nozzle in the printer's settings after the upgrade, and Prusa says to configure the slicer for your printer model and nozzle diameter.

If you can't find the part listed for your model, treat fit as unknown. Unknown fit is not fit.

How can you tell a nozzle or extruder is wearing?

Wear is gradual, so it's easy to miss. Watch for:

• A larger or misshapen nozzle opening. Bambu Lab's P1S guide shows a stainless nozzle with a visibly enlarged orifice after 10 hours of PETG-CF. Polymaker lists an enlarged or misshapen orifice and visible wear or scratches as signs to replace a nozzle.
• Persistent clogs despite cleaning, another replacement sign Polymaker lists.
• Under-extrusion, slipping filament, or skipped layers, which Bambu Lab links to worn extruder gears.

These symptoms also have other causes, including wet filament, partial clogs, and wrong temperature or flow settings. Don't replace parts based on one symptom. Our worn nozzle guide covers how to check a nozzle for wear, and our clog diagnosis guide walks through the competing causes one at a time.

Ventilation still applies

Filled filaments are still heated plastics. NIOSH reports that desktop filament printers emit respiratory irritants, and that "printing with nanomaterial containing filaments" leads to emission of nanomaterial-containing particles. Print in a well-ventilated space, not where people sleep. An enclosure helps some materials print, but it is not a ventilation solution, and no filament is emission-free. Our ABS vs ASA guide covers ventilation priorities in more detail.

Carbon fiber filaments also don't make a part structural. Don't use printed parts for safety-critical loads, food contact, or electrical safety.

Checklist before you print an abrasive filament

• Read the filament maker's page or data sheet for a nozzle requirement. Ask the maker if it isn't stated.
• Identify your exact printer model, hotend, and revision.
• Find the wear-resistant nozzle or hotend your printer maker lists for that model.
• Choose a diameter both makers recommend. Avoid 0.2 mm and similar small nozzles for filled filaments.
• Check the extruder gears and feed path, including any multi-material unit, for abrasive-filament guidance.
• Read the cleaning guidance for your nozzle, especially if it is coated.
• Follow the maker's nozzle-change procedure, and update the printer and slicer settings.
• Plan ventilation, and dry storage for hygroscopic filled materials such as nylon blends. See filament storage.
• Inspect the nozzle and gears regularly while printing abrasive filaments.

For more, see the nozzles hub and the specialty filaments hub.

Nozzles: what to check before you buy ↗