New 3D Printing Technique by TU Delft and MIT

Researchers at Delft University of Technology and MIT have developed a novel 3D printing technique called Speed-Modulated Ironing, enabling high-resolution surface textures and colour gradients using just a single material. By using one nozzle to 3D print and the second nozzle to re-heat printed areas at varying speeds, the team controls colour and texture of temperature-responsive materials. The work is presented at the ACM Symposium on User Interface Software and Technology (UIST).

Material extrusion 3D printing is being used for an increasingly wide range of applications. A major goal for researchers and makers in this field is to create 3D objects with multiple properties in a single print. Current methods for achieving multi-colour or multi-property prints often involve using multiple materials, limiting the ability to create smooth transitions and fine gradients in the properties of printed objects.

The Speed-Modulated Ironing technique relies on a standard dual-nozzle printer. For every layer, the first nozzle deposits the material. Then, without extruding any material, the second nozzle scans over the printed layer at varying speeds to activate the material.

Speed-Modulated Ironing eliminates these limitations by leveraging the temperature responsiveness of filaments like Woodfill, Corkfill, and foaming filaments. This novel approach uses a dual-extruder 3D printer, where one nozzle deposits the material, and a second (empty) nozzle moves over the printed layer, “ironing” it with a constant temperature but at varying speeds. Ironing at lower speeds activates the material more, while ironing faster activates it less. This principle allows to control the resulting properties of the print, such as colour shades, translucency, and tactile textures.

Using speed variations

"In attempting to utilise the temperature response, we realised that varying the speed of a nozzle is much more accurate and instant compared to changing its temperature," says lead researcher Mehmet Ozdemir. "This is the key for our fine-grained control of the applied heat”. However, every material responds in a different way to the ironing. The researchers therefore set up a theoretical model to predict the expected activation of the material. “Our model was essential for understanding the inner workings of Speed-Modulated Ironing and for fine-tuning the process,” says Marwa AlAlawi, PhD student at MIT.

Varying the ironing speed enables controlling the heat transferred into the material with precision. This allows high-resolution programming of visual and tactile properties of the printed object.

For those who want to explore this technology hands-on, the researchers have developed a design tool that implements the Speed-Modulated Ironing workflow. Users can assign specific visual and tactile properties to 3D models and send the files for printing. The researchers hope that this is just the beginning, as Doga Dogan (MIT) adds: “By making the design tool open source, we aim to enable the 3D printing and maker communities to experiment with this method and develop it further.”

Speed-modulated ironing enables a large range of colour shades and high-resolution images on prints.

Potential Applications and Looking Ahead

Speed-Modulated Ironing allows 3D printed parts to have features such as text, images, logos and QR codes, all using one single material, Also, 3D scanned objects can be reproduced with not just the geometry but also shade. “This is an exciting new way to create textures in 3D prints, further enhancing the capabilities of FDM printing “, says Paul Kuiper from Ultimaker, the 3D printing company that supported this project.

Looking at the future, Zjenja Doubrovski (Assistant Professor at TU Delft) says: "We believe that this technique is an important step towards using fewer materials while offering more versatile and expressive fabrication results. We are thrilled to see how this technology will inspire further explorations and innovations in the field of 3D printing."

Precise control of colour and texture on objects allows many possibilities, such as QR codes, logos or text on prints and reproducing 3D scanned objects with texture.