In large-scale additive manufacturing, extrusion systems tend to force a trade-off. Higher output usually means heavier hardware, which in turn demands stronger gantries or robotic arms and reduces positional precision. Smaller extruders offer better control but cannot match the throughput needed for structural components. Researchers at the U.S. Department of Energy’s Oak Ridge National Laboratory believe they have found a way around that constraint.
Bian, T., Colomer, G., Liu, Y., Tius, M. A., & Zhang, Z. (2025). Deoxygenative Difunctionalization of Aldehydes via Ketyl Radical and Light/Dark Pd Synergy. Angewandte Chemie International Edition. https://doi.org/10.1002/anie.202521847
Led by Halil Tekinalp, the team has developed a modular extrusion system that combines the output of multiple smaller extruders into a single, coordinated material stream. Rather than scaling up one large extrusion head, the approach distributes the load across parallel units and merges their molten polymer flows through specially engineered nozzle blocks. The result is a high-output system that maintains the responsiveness and control of smaller extruders while approaching the deposition rates of much larger equipment.
Led by Halil Tekinalp from Oak Ridge National Laboratory stated,
“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.”
The mechanical challenge is straightforward but difficult to solve. Large extruders are heavy and introduce inertia into motion systems, especially in gantry-based printers. That added mass can reduce accuracy during rapid direction changes and create inconsistencies at lower flow rates. It can also contribute to heat buildup, increasing the risk of warping in tapered or thin-walled geometries. By contrast, ORNL’s approach allows individual extruders to be activated or deactivated depending on the required output, without physically swapping hardware.
At the center of the system is a patent-pending nozzle architecture designed to merge parallel melt streams. The nozzle blocks, fabricated from aluminum bronze for thermal conductivity and mechanical durability, contain internal channels that guide two molten polymer streams into a unified bead. A Y-shaped configuration improves flow uniformity and reduces centerline porosity, a common issue in high-throughput extrusion where incomplete fusion can weaken parts.
In addition to the Y-shaped design, the team engineered a nozzle capable of producing core-and-sheath structures, where one material encapsulates another within the same extruded bead. This configuration enables true multi-material printing within a single pass. Instead of switching extruders between layers or segments, different materials can be deposited simultaneously in controlled geometries. According to Vipin Kumar, a technical lead on the project, this architecture allows dynamic material transitions while preventing cross-contamination between feedstocks.
From a materials engineering standpoint, the implications are significant. Multi-material beads can combine stiffness and flexibility, or structural strength and functional properties such as electrical conductivity or flame resistance. Embedding a composite core within a thermoplastic sheath may also improve interlayer adhesion, addressing delamination, a persistent limitation in large-format polymer additive manufacturing.
The system is compatible with pellet-based feedstocks, which are commonly used in large-scale printing for cost efficiency. Early testing indicates that the multiplexed configuration can double flow rates compared with a single extruder of comparable scale, with potential for further increases depending on the number of active units. Importantly, higher output does not appear to compromise bead consistency at lower flow conditions, which has historically been a weakness of oversized extrusion heads.
Oak Ridge National Laboratory has long focused on scaling additive manufacturing for industrial use, particularly in energy, aerospace, and defense applications. In those sectors, the ability to fabricate large components with tailored mechanical properties is increasingly relevant. Aerospace structures may require sections with impact resistance integrated alongside lightweight support regions. Energy infrastructure components may demand flame-retardant housings combined with load-bearing frames. Civil engineering applications such as bridge elements or marine structures often involve varied stress profiles within a single part.
The modular extrusion concept is intended to support that level of design freedom without introducing excessive machine mass or sacrificing process control. Because individual extruders can be independently managed, manufacturers gain flexibility in balancing throughput and precision across different build phases. A thick structural region may call for maximum combined output, while a finer feature could be printed with only one active unit.
The broader context for this development is the ongoing push to industrialize additive manufacturing beyond prototyping. As print volumes increase and parts move into structural roles, process reliability and repeatability become central concerns. Innovations in nozzle geometry and melt-stream management, such as those demonstrated here, address bottlenecks that have limited polymer-based systems at larger scales.
While further validation and integration into commercial platforms will be required, the work from Oak Ridge National Laboratory suggests that extrusion-based additive manufacturing does not need to rely on larger and heavier components to increase output. Instead, distributing flow across coordinated modules may offer a more scalable path forward, combining throughput, material versatility, and mechanical performance within a single system.
Adrian graduated with a Masters Degree (1st Class Honours) in Chemical Engineering from Chester University along with Harris. His master’s research aimed to develop a standardadised clean water oxygenation transfer procedure to test bubble diffusers that are currently used in the wastewater industry commercial market. He has also undergone placments in both US and China primarely focused within the R&D department and is an associate member of the Institute of Chemical Engineers (IChemE).
