The importance of nozzles in high-speed FFF printing

High-speed FFF 3D printing requires extruding large volumes of material per second. The maximum volumetric flow is defined by the product: nozzle diameter × layer height × print speed. On desktop printers, the default value is around ~15 mm³/s for PLA and ~10 mm³/s for ABS/ASA/PETG. However, it is worth noting that, for example, ASA can achieve higher flows than PLA, because its properties require less layer cooling time. Exceeding these values without losing quality requires modifying the hotend/nozzle design to increase the contact area between the hotend’s heating zone and the filament to melt the plastic faster.

Image 1: Schematic of hotend operation. Source: Nature.com

Traditional Design: Volcano and SuperVolcano

A classic strategy has been to extend the heater block (melt zone). For example, E3D Volcano-type hotends use a longer aluminum block, increasing the melt zone. This boosts the volumetric flow by ~70% compared to a standard V6 hotend. The following figure shows a Volcano hotend with its large melt block:

Image 2: E3D Volcano hotend with extended melt zone. Source: E3D.

E3D even developed the SuperVolcano, with an even longer block and a more powerful heater. According to E3D, the SuperVolcano can reach 11 times the flow of a standard V6 (practically up to ~32 mm³/s with PLA at 0.4 mm nozzle and 0.2 mm layer). These nozzles allow printing with large diameters (0.6–1.4 mm) at very high speeds, producing thick lines and strong layer bonds. However, they require higher temperatures and heating power to keep the filament molten.

Multi-channel Nozzles: CHT and High Flow

The latest strategy involves multi-channel nozzles: internal designs that split the filament into multiple paths to melt it from the inside. Bondtech (under the 3DSolex brand) pioneered CHT® (Core Heating Technology), using 3 internal melt channels. Unlike standard nozzles (which melt from the outside in), CHT splits the filament core into three flows, dramatically increasing the melt zone. This improves flow without changing the hotend; tests show a CHT nozzle increases volumetric flow by ~30% over a standard V6. Additionally, CHT nozzles usually operate at lower temperatures for the same flow and allow large output diameters.

Image 3: CHT nozzles. Source: Bondtech.

E3D has also released four-channel multi-channel designs. Examples include the Unicorn nozzle (in collaboration with Creality) and the new High Flow nozzles for modern extruders. These divide the filament into 4 internal channels, greatly increasing contact area and heat transfer. The image below shows a cross-section of an E3D “Unicorn” nozzle (brass top, ObXidian bottom); internally, the filament paths are multiplied:

Image 4: Cross-section of E3D/Creality “Unicorn” multi-channel nozzle. Internal design splits the filament into four channels, increasing the melt surface. Source: E3D.

This design allows the Unicorn nozzle to reach very high flows: up to 52 mm³/s, enabling printing at ~600 mm/s while maintaining continuous extrusion. Prusa Research also adopted a similar nozzle (developed by E3D) for the MK4 Nextruder, highlighting that the 4-channel geometry “increases contact area and improves volumetric flow.” In short, more channels = more internal melt area = higher flow.

Volumetric Flow Comparison

In numbers, high-flow nozzles outperform conventional ones:

• Standard V6 nozzle (0.4 mm, 0.2 mm layer): typically ~10–15 mm³/s (PLA ~15 mm³/s; ABS, PETG ~10 mm³/s). This is the common limit on unmodified desktop printers.
• Volcano hotend (0.4 mm, 0.2 mm): ~20 mm³/s (≈+70% over V6) thanks to the extended block.
• SuperVolcano hotend: up to ~32 mm³/s with PLA (11× V6) combining larger area and power.
• Bondtech CHT nozzle (3 channels): increases flow ~30% over a standard V6 (~18–20 mm³/s).
• E3D Unicorn / High Flow nozzle (4 channels): reaches ~52 mm³/s (0.4 mm, PLA), far above conventional nozzles.
• Raise3D Pro3 HS (Hyper FFF): redesigned hotends double volumetric flow (up to +200%), extruding much more material per second with the same nozzle diameter.

These figures show that advanced nozzle designs enable printing at speeds (>300–600 mm/s) impossible with standard nozzles, without under-extrusion during rapid movements.

Raise3D Solutions for High Speed

Raise3D leads commercial high-speed FFF printing. Its Hyper FFF kit (for Pro3 printers) integrates global hardware and software improvements. It includes redesigned high-flow hotends (capable of doubling volumetric flow) and firmware with resonance compensation. The new Pro3 HS series comes factory-ready with high-flow hotends: each Pro3 HS includes a high-flow silicon carbide nozzle and Hyper Core filaments, allowing printing of composites at 200–300 mm/s with high reliability.

Image 5: Raise3D Hyper Speed kit for Pro3 HS series, with high-flow hotends and optimized filaments. Source: Raise3D.

In summary, Raise3D combines advanced nozzles/high-flow hotends (Pro3 HS max flow = +200%) with tailored filaments and firmware. Their integrated mechanical and material approach maximizes productivity, reducing print times by 30–70% without sacrificing quality.

Conclusion

Nozzle design is critical for high-speed FFF printing, as it directly limits volumetric extrusion. Raising this limit requires increasing the melt zone—either by lengthening the aluminum block (Volcano, SuperVolcano) or using multi-channel designs that melt filament internally (Bondtech 3-channel CHT, E3D 4-channel nozzles, etc.). These solutions allow several times higher flows than traditional nozzles, enabling much faster printing speeds. Raise3D stands out by integrating high-flow nozzles (ceramic/hardmetal) in Hyper FFF systems, doubling extruder flow and fully exploiting high-speed printing. In short, advancing nozzle design (increasing contact area and thermal efficiency) is key to printing faster without sacrificing quality.