Researchers at Oak Ridge National Laboratory (ORNL) have developed an extrusion system that combines multiple 3D printing extruders into a single high-output stream, using specially designed nozzles. 

Aimed at a longstanding trade-off between speed and precision in large-format additive manufacturing, the system matches the output of larger extruders while retaining the flexibility and precision associated with smaller ones, and also adds the ability to print with multiple materials simultaneously within a single bead.

Large-format extruders used in AM are heavy and require expensive, heavy-duty gantries or robots to operate. Their precision can diminish at low output, which results in inconsistent flow that complicates the printing of both small components and larger tapered designs, and printing speeds often have to be reduced to prevent heat-related warping and failure.

ORNL’s system allows operators to switch smaller extruders on or off without a loss of quality and to print with multiple materials in the same pass, without swapping equipment.

“By enabling smaller-scale extruders to match the output of larger systems without the burden of extra weight—and by achieving unprecedented multi-material extrusion within the bead—this system is poised to redefine extrusion-based additive manufacturing,” said Halil Tekinalp, lead researcher on the project at ORNL.

“These advancements will help strengthen U.S. manufacturing competitiveness and expand access to cutting-edge production technologies.”

How it works

The system was built around patent-pending nozzle blocks made from aluminum bronze, chosen for its strength and thermal conductivity. Inside each block, molten polymer streams from two parallel extruders merge into one, consistently doubling flow rate compared with a single extruder, and researchers said additional streams could triple or quadruple that figure.

A separate core-and-sheath nozzle produces beads in which one material encases another. That allows materials with different mechanical properties to be combined precisely within a single bead rather than printed as separate parts.

Possible applications

The multi-material precision allows for parts that combine distinct properties in a single piece, the researchers said. Aerospace uses could include crash-safe or radar-absorbing panels, and energy uses could encompass flame-resistant enclosures and lightweight modular housing for battery racks or thermal systems. 

Defense applications have the potential to range from lightweight shelters to protective panels, while civil uses include reinforced bridge decks, car bumpers and boat hulls.