Key takeaways
- The nozzle's material decides what you can print. Its diameter only decides how long the print takes and how the surface looks.
- A worn nozzle doesn't fail suddenly. It widens gradually, and the first symptoms are a worsening surface and drifting hole sizes — easily blamed on the material.
- Moving to 0.6 mm is the cheapest way to cut print time on thick parts, but recheck wall count: four 0.4 mm walls aren't as thick as four 0.6 mm walls.
- Thin layers and small nozzles give a better surface, not a stronger part.
The nozzle is the cheapest part on the printer and the one that decides the most. It sets the ceiling on which materials you can print and on the flow you can reach, and when it wears, every print after that is off — with no warning light to tell you.
Four kinds of nozzle, and what each is for
| Type | Thermal conductivity | Wear resistance | Right for |
|---|---|---|---|
| Brass | Best | Low | PLA, PETG, ABS, ASA, TPU, PC — every unfilled plastic |
| Hardened steel | Noticeably lower | High | Every carbon- or glass-filled material |
| Bimetal (copper body, steel tip) | Close to brass | High | Printing a lot of filled material while needing high flow |
| Ruby or carbide tip | Low | Very high | Workshops running PA6-GF continuously; several times the price, only pays off at volume |
Conductivity is not a minor detail. At the same set temperature, a more conductive nozzle reheats the melt zone faster after each stretch of extrusion, so it sustains high flow without under-extruding. That is why bimetal nozzles exist: they try to keep copper's conductivity and steel's wear resistance.
Makers choose differently and say so on their spec sheets. Prusa fits a 0.4 mm high-flow brass CHT nozzle on the MK4S and CORE One+. Creality fits a hardened steel nozzle on the K2 Plus, with a 350 °C ceiling. QIDI uses a bimetal nozzle on the Plus 4. Those three choices speak to three different customers, not three levels of quality. See sources.
Why fibre wears nozzles so fast
Chopped carbon and glass fibres are harder than brass, and they pass through the bore at speed in the hot plastic stream. Every metre takes a little metal from the edge of the bore. The bore doesn't clog — it widens, and gradually rounds into a funnel.
The material background is in carbon fibre vs glass fibre filament: the higher the fibre loading, the faster the wear, and PA6-GF wears faster than PLA-CF for the same weight.
Diameter: trading time for detail
The flow you need is a simple product: line width × layer height × speed. With line width set to about 120 % of nozzle diameter — what we recommend in print settings for strength — the table below shows why changing the nozzle has more effect than any speed tweak.
| Nozzle | Line width | Typical layer | Flow at 200 mm/s | Use for |
|---|---|---|---|---|
| 0.2 mm | 0.24 mm | 0.05–0.12 mm | ≈ 4 mm³/s at 0.08 mm | Small model detail, embossed text, narrow slots |
| 0.4 mm | 0.48 mm | 0.12–0.24 mm | ≈ 19 mm³/s at 0.20 mm | The default. Best balance for almost everything |
| 0.6 mm | 0.72 mm | 0.20–0.36 mm | ≈ 43 mm³/s at 0.30 mm | Thick parts, fixtures, load-bearing parts |
| 0.8 mm | 0.96 mm | 0.30–0.50 mm | ≈ 58 mm³/s at 0.40 mm and 150 mm/s | Large blocks, prototype moulds, parts with no surface requirement |
The flow column is where the printer says "no". Every hot end has its own flow limit, and beyond it you get under-extrusion, not a faster print. Makers have started publishing this figure: Creality says the 100 W heater on the K2 Plus takes ABS at 280 °C up to 40 mm³/s. Against the table above, that's enough for a 0.6 mm nozzle at 0.3 mm layers — and not enough for 0.8 mm at thick layers.
A small nozzle doesn't make a stronger part
This is the most common misunderstanding about diameter. Parts get stronger from more material in the load-bearing section and from good bonds between layers, and thick layers with wide lines help both: each bond gets more hot plastic and cools more slowly. A 0.2 mm nozzle gives a nicer surface and usually a weaker part for the same print time.
Choose the nozzle material by what you print. Choose the diameter by what you need: surface, or time.
Quick choice
If you just want one answer
- Only plain PLA and PETG
- Brass 0.4 mm. Change nothing.
- Some matte PLA or PLA-CF
- Hardened steel 0.4 mm. Cheaper than a spool.
- PA-CF, PETG-CF, PA6-GF
- Bimetal 0.4 or 0.6 mm; keep a spare.
- Fixtures and thick parts, no surface requirement
- Brass or bimetal 0.6 mm.
- Small detailed models
- Brass 0.2 mm, and accept print times several times longer.
If you're weighing whether your current printer can reach the material you need, what can my 3D printer print comes before this article. Print settings for each material are on the catalogue page.
Frequently asked
How much filled material can a brass nozzle print before it wears?
There is no general figure, because it depends on fibre loading, fibre type and flow. The usual order of magnitude is a few hundred grams with carbon-filled material, and less with glass fibre. The problem is you don't see it happen: the bore widens gradually, so parts mid-batch still look usable while tolerances drift.
Does hardened steel make prints worse?
Not in quality, but it reduces flow headroom. Steel conducts heat worse than brass, so at high speed you may need 5–10 °C more nozzle temperature than a brass profile to hold the same flow. If you print fast and print a lot of filled material, a bimetal nozzle solves exactly this.
Should I switch to 0.6 mm for everything?
For a workshop making fixtures and functional parts, yes — it's one of the biggest time savers that costs nothing in material. For model makers, no: 0.6 mm can't hold small detail, embossed text or narrow slots. The sensible approach is to own both and change by job.
How is a clogged nozzle different from a worn one?
A clog drops flow suddenly: under-extrusion, missing layers, clicking at the extruder. Wear raises flow gradually: wider lines, bulging walls, shrinking holes. If the symptoms go up rather than down, don't clear the nozzle — replace it.
Does TPU need a special nozzle?
No. TPU isn't abrasive; what it needs is a short, straight path from the drive gear to the nozzle — a direct-drive extruder rather than a remote one. Details in the TPU printing guide.