Above: Rotational 3D Printing uses a rotating nozzle to deposit ink composed of short fibres/Image Credit: Harvard SEAS
In the quest for improving the strength of 3D printed parts, researchers at Harvard John A Paulson School of Engineering and Applied Sciences (SEAS) have struck gold with their new technique called Rotational 3D printing. It allows for optimal control over the use and deposition of short fibres while printing thus enabling ultra-strong parts.
This technique can be equated to the ancient method of mixing straw in mud to build stronger mudbricks. This method was later used in construction and such composites are created even now to create the perfect blend of materials for required applications.
Above: Demonstration of the orientation of fibres within an ink from a previous paper published by Compton and Lewis/
Image Credit: “3D-Printing of Lightweight Cellular Composites,” Advanced Materials
The new 3D printing technique, ‘Rotational 3D printing’ offers optimal or near-optimal control over deposition of short fibres embedded in polymer matrices. The key to this unprecedented control lies in the rotation of the print nozzles by using a stepper motor. By precisely controlling the speed and rotation of the 3D printer nozzle the fibres can be deposited through the material at appropriate locations and in required quantities to build the perfect structure. This sort of product will not only be strong and stiff but at the same time be light weight due to less usage of material.
The stepper motor controls the angular velocity of the rotating nozzle out of which the ink is extruded just as in every FDM process. However, the researchers argue that rotational 3D printing is not exclusive to any particular 3D printing method. It can be augmented to suit the existing additive manufacturing processes like FDM, direct ink writing and even large scale thermoplastic 3D printing and they can be made to print stronger and highly damage resistant parts.
Jennifer Lewis, Senior researcher of this study explains, “Being able to locally control fibre orientation within engineered composites has been a grand challenge. We can now pattern materials in a hierarchical manner, akin to the way that nature builds.”
The implications of the success of this method are huge. According to Harvard University, the control of fibres can be applied to various fields and many different filler and matrix combinations can be implemented to improve the optical, electrical and even thermal properties of the 3D printed objects.
Researcher and Assistant Professor of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania points out that, “One of the exciting things about this work is that it offers a new avenue to produce complex microstructures, and to controllably vary the microstructure from region to region. More control over structure means more control over the resulting properties.”
This research and its findings are published in the journal of Proceedings of the National Academy of Sciences of USA (PNAS). It was carried out in the famous Lewis Lab at Harvard. Other collaborators in the research include Brett Compton, now Assistant Professor in Mechanical Engineering at the University of Tennessee, Knoxville & visiting PhD student Jochen Mueller from ETH Zurich.
The Harvard Office of Technology Development has protected the intellectual property relating to this project.
