No glue required: Wood and metal bonded with sound and 3D printing

This is important folks.  Understand that we have depended on sheet steel or its metallic equivalent for around two centuries and this is because wood demanded real joining tech like screws and nails and craftmanship.

Now we can join 3D metal to really good wood. This knocks weight out and produces a much nicer product.  3D may well have found a natural niche.

It will even be quiet.  I now like 3D metallics.

Now how about 3D printing hardware like hinges onto the wood.  furniture manufacture can go back to craft quality manufactured wood fitted with hardware and no use of glue.

No glue required: Wood and metal bonded with sound and 3D printing

By Michael Franco

August 28, 2024

https://newatlas.com/materials/adhesive-free-bonding-wood-metal/

In Ultrasonic Joining, two materials like wood and metal are joined by heat produced from the friction of sound waves

Manufacturing could be dramatically changed thanks to two new techniques for joining materials created by scientists in Austria. The two methods create super strong bonds at the pore level, eliminating the need for caustic adhesives.

While industrial adhesives are great for joining part A to part B, they're not really very good for the environment, especially those made from petroleum-based chemicals. Not only do these adhesives require a good deal of energy and resources to produce, but their manufacture can produce harmful pollutants; plus, once the items in which they've been used reach the end of their lifecycle, they can contaminate soil and groundwater. Additionally, some of the chemicals used in adhesive production can be harmful to the workers using them.

While there has been quite a push to create more eco-friendly adhesives, from such things as a reusable glue made from plants to an adhesive that biodegrades after use, researchers at the Graz University of Technology (TU Graz) in Austria took another approach. Two other approaches, actually, both of which achieved bonds between a variety of wood types and two types of plastics, stainless steel, and a titanium alloy.

In the first, the researchers used a 3D-printing process they termed "Addjoining." They were able to 3D print the various materials directly onto a piece of untreated wood in such a way that they penetrated the pores in the wood, forming a bond in much the same way an adhesive would. The team then snapped the bond apart.

“After the (bond) 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,” explains Gean Marcatto, who worked on this process as a postdoc at TU Graz's Institute of Materials Sciences, Joining and Forming.

The team believes that the 3D-printed bonds could be made even stronger if the wood was etched using lasers to create more complex structures or larger pores for the other material to bond with.

“But we wanted to work with as few steps as possible and, above all, without chemicals,” says Sergio Amancio, who led the research. “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.”

The "Addjoining" technique 3D prints a material like the plastic composite seen here straight into the pores of an untreated piece of lumber

Wolf/TU Graz

A sound approach

The second joining technique the researchers came up with was called "Ultrasonic Joining." It used an instrument called a sonotrode to send high-frequency, low vibration waves through the juncture of the wood and the metal polymers. This created friction, which generated enough heat to bond the two materials together.

“This technique is particularly suitable for large components and 2D structures since we achieve a precisely localized spot joint,” says Awais Awan, a co-author on the study.

The researchers believ chnique is particularly suitable for large components and 2D structures since we achieve a precisely localized spot joint,” says Awais Awan, a co-author on the study.

The researchers believes their new green joining techniques can have applications in the furniture, automotive and airline industries. es their new green joining techniques can have applications in the furniture, automotive and airline industries.