Sound weaves unlikely bond between metal, wood in a 3D printing breakthrough

Two innovative methods for material joining have been developed by scientists at Graz University of Technology (TU Graz) in Austria. These techniques could significantly transform the manufacturing industry.

By eliminating the need for environmentally harmful adhesives, they create remarkably strong bonds at the pore level of materials.

This advancement opens new possibilities for sustainable manufacturing.

Tackling environmental challenges with new joining techniques

Traditional industrial adhesives, while effective for joining materials, pose significant environmental challenges. Most adhesives are petroleum-based, requiring substantial energy and resources for production.

Additionally, their manufacturing processes often release harmful pollutants, and once the products reach the end of their lifecycle, these adhesives can contaminate soil and groundwater. The chemicals involved in adhesive production also present health risks to workers.

In response to these issues, researchers at TU Graz have introduced two groundbreaking techniques that offer eco-friendly alternatives to conventional adhesives .

The first method, termed “Addjoining,” leverages 3D printing technology to create bonds directly within the pores of untreated wood. This approach eliminates the need for external adhesives, reducing both environmental impact and potential health hazards.

Addjoining: A game-changer in material bonding

The Addjoining process involves 3D printing various materials, such as wood, plastics, stainless steel, and titanium alloy, directly onto untreated wood. By penetrating the wood’s pores, the printed materials form a bond similar to that achieved with traditional adhesives. This method has demonstrated effectiveness across different types of wood and plastics.

Gean Marcatto, a postdoc at TU Graz’s Institute of Materials Sciences, Joining and Forming, explained the method in the press release.

“After the joint fractured, we were able to find polymer in the wood pores and broken wood fibers in the polymer, which suggests that the fracture occurred in the wood and polymer, but not at the joint,” said Marcatto.

This observation indicates that the bond created by Addjoining is exceptionally strong and integrated at the pore level of the wood.

The team anticipates that the strength of these 3D-printed bonds could be further enhanced by etching the wood with lasers to create more complex structures or larger pores, which would improve the bonding surface .

Sergio Amancio, who led the research, adds , “But we wanted to work with as few steps as possible and, above all, without chemicals. We can use this technology particularly well with complicated 3D geometries because the components are printed directly onto the surface – in whatever geometry is required.”

Ultrasonic joining: Precision meets efficiency

The second innovative joining technique is known as “Ultrasonic Joining.” This method employs a sonotrode to generate high-frequency, low vibration waves that travel through the interface of wood and metal polymers. The resulting friction produces enough heat to create a strong bond between the materials.

In the press release, Awais Awan, a co-author of the study, notes , “This technique is particularly suitable for large components and 2D structures since we achieve a precisely localized spot joint.” Ultrasonic Joining offers a precise and efficient bonding solution, especially for applications involving larger components where traditional adhesives might be less effective.

The researchers believe that these new green joining techniques hold significant promise for various industries, including furniture manufacturing, automotive production, and aerospace. By eliminating the need for traditional, harmful adhesives, these methods not only enhance sustainability but also improve the overall quality and durability of the bonded materials.

The groundbreaking research was recently presented at the IIW Annual Assembly and International Conference on Welding and Joining , held in Rhodes, Greece.