ORNL Develops Modular Extrusion System for Precise Multi-Material 3D Printing

Large-scale extrusion-based 3D printing faces a well-known trade-off: high deposition rates require large extruders that are heavy and lose precision, while smaller systems offer higher accuracy but limit throughput. Researchers at Oak Ridge National Laboratory have now presented an extrusion concept that combines several smaller extruders into a shared material flow via specially designed nozzles, thereby merging the advantages of both approaches.

The developed setup bundles parallel extruders into patent-pending nozzle blocks made of aluminum bronze. The material offers high strength and good thermal conductivity, which are crucial for stable melt flow. The internal nozzle geometry merges the polymer melts without significantly increasing the diameter of the extrusion head. As a result, the system achieves flow rates comparable to large pellet extruders while remaining far more flexible to handle.

A key feature is the ability to process multiple materials simultaneously within a single extrusion strand. According to project leader Halil Tekinalp, individual extruders can be activated or deactivated as needed without compromising print quality.

“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 ORNL researcher Halil Tekinalp, who led the project. “These advancements will help strengthen U.S. manufacturing competitiveness and expand access to cutting-edge production technologies.”

In addition, a nozzle geometry was developed that produces so-called core-and-sheath strands, in which one material forms a core and is encapsulated by a second material. This structure makes it possible to deliberately combine mechanical properties and improve interlayer adhesion.

“This innovation opens up new manufacturing horizons, making it possible to achieve complex, efficient and creative designs with dynamic material switching, all while preventing cross contamination — meaning the distinct materials remain pure and do not mix unintentionally,” said Vipin Kumar, another technical lead on the project.

The work was carried out at ORNL’s Manufacturing Demonstration Facility and supported by the U.S. Department of Energy. It demonstrates how polymer-based large-format 3D printing can be further advanced through modular extrusion to better combine productivity, material diversity, and process control.