Glossary · Filament

3D printing

Abrasive filaments

Printing materials with hard additives such as carbon or glass fibres, glow pigments or metal powder. During printing, they gradually wear away the small metal tip the plastic comes out of.

Explained in more detail

Hard fillers in the plastic make a filament abrasive: short carbon or glass fibres, strontium aluminate in glow-in-the-dark filaments and metal powder, and to a lesser degree wood fibres, glitter, marble or stone particles and mineral matting agents. As they flow through, the particles wear out the bore of the nozzle, and a brass nozzle can widen noticeably after as little as 0.5 to 2 kg of glow filament. The results are wider, uneven lines, under-extrusion, more stringing and inaccurate dimensions, even when normal PLA is printed afterwards. The remedy is nozzles made of hardened steel, tungsten carbide or with a ruby tip. Hardened steel conducts heat much worse than brass, at around 16 to 22 W/mK against about 105 W/mK, so some profiles use a slightly higher temperature or a lower maximum flow. Unhardened drive gears in the extruder and the feed paths of multi-colour systems also wear out.

Where does the term come from?

From Latin abradere, to scrape or scratch off. Abrasion and abrasives such as sandpaper or blasting media also come from it.

In practice

• If the spool says "hardened nozzle recommended" or has an addition such as CF, GF, Glow or a metal name, the filament is abrasive.
• Despite its harmless appearance, glow-in-the-dark is one of the most abrasive filaments, and a brass nozzle suffers after only 0.5 to 2 kg.
• Glitter, marble, wood and matt are only mildly abrasive: occasionally brass is enough, but for many kilograms a hardened nozzle is worthwhile.
• You recognise wear by a widened, out-of-round opening, uneven lines and suddenly more stringing without another cause.
• Do not use a 0.2 mm nozzle with particle filaments; with fibres, 0.6 mm is often more reliable than 0.4 mm.

Not to be confused

Fluorescent neon filaments are not abrasive: they contain dyes instead of hard particles. Only the glow-in-the-dark types are abrasive.

Frequently asked questions

Do I need a hardened nozzle for carbon filament?

Yes. For CF and GF filaments, manufacturers expressly require a hardened nozzle, for example made of hardened steel. Many current printers have one from the factory, which is stated in the datasheet.

How quickly does a brass nozzle wear with glow-in-the-dark filament?

After just 0.5 to 2 kg, the opening can widen noticeably. After that, the nozzle prints inaccurately even with normal PLA and should be replaced.