US scientists develop adaptive nozzles for improved 3D printing

A team at Johns Hopkins University has developed a new 3D printing technique that uses a nozzle that can change its size and shape during the printing process to overcome the trade-off between speed and resolution that exists in traditional 3D printers with fixed nozzle diameters.

The researchers emphasize that the new nozzle, known as AN3DP, could improve the printing of a wide range of objects, from aerospace components to soft electronic devices and structural beams. The results of the study were published in the journal Science Advances.

“Traditional 3D printers use fixed nozzles, which limit either resolution or speed. Smaller nozzles improve resolution but slow down printing, while larger nozzles increase speed but reduce detail. AN3DP’s design overcomes this by adjusting to the specific requirements of each feature being printed, allowing for both high resolution and faster printing,” said corresponding author Jochen Mueller, assistant professor in the Whiting School of Engineering’s Department of Civil and Systems Engineering, who worked with Seok Won Kang, a postdoctoral fellow, on the project.

“One of the major benefits of this adaptive nozzle is its ability to reduce the ‘stair-stepping’ effect, which is common in traditional 3D printing,” said Mueller. “This effect, reminiscent of the blocky figures in the popular game Minecraft, occurs when sloped or curved surfaces are printed using fixed nozzle sizes, resulting in a series of small, visible steps rather than a smooth surface. By adjusting the nozzle shape and size during the printing process, we can create smoother, continuous surfaces, enhancing the overall quality of printed objects.”

Inspired by mechanisms such as retractable grasping tools and tendons in humans and animals, AN3DP uses eight movable pins that are controlled by motors to change their shape and size. An elastic membrane connects the pins and ensures that the material exiting the nozzle maintains a smooth shape. This combination of moving pins and elastic membrane enables the precise production of highly complex structures.

“I’m really excited about AN3DP and its future applications. Its flexibility is going to improve the structural integrity and functionality of printed objects, making them more suitable for complex engineering applications,” said Mueller.

While AN3DP solves two major problems in 3D printing – accuracy and speed – there are still challenges, according to the team. For example, the current nozzle design requires manual assembly and cleaning and can only be used for a single manufacturing process. Mueller and Kang plan to address these limitations by further refining the design and adapting it to the common 3D printing technique of fused filament fabrication to expand its application areas.