Researchers have developed a new metal 3D printing method that could help reduce costs and make better use of resources. The new method, developed by a team led by the University of Cambridge, allows structural modifications to be ‘programmed’ into metal alloys during 3D printing, fine-tuning their properties without the thousands-year-old ‘heating and beating’ process.
The new 3D printing method combines the best of both worlds: the ability to create complex shapes with 3D printing and the ability to engineer the structure and properties of metals with traditional methods. The findings were published in the journal Nature Communications.
Issues with traditional metal 3D Printing
3D printing has several advantages over other methods of manufacturing. For example, 3D printing makes it far easier to produce intricate shapes and uses far less material than traditional metal manufacturing methods, making it a more efficient process. It does, however, have significant drawbacks.
“There’s a lot of promise around 3D printing, but it’s still not in wide use in industry, mostly because of high production costs. One of the main drivers of these costs is the amount of tweaking that materials need after production.”
– Dr. Matteo Seita from Cambridge’s Department of Engineering, who led the research.
Metal parts have been made through a process of heating and beating since the Bronze Age. This method of hardening the material with a hammer and softening it with fire allows the maker to form the metal into the desired shape while also imparting physical properties such as flexibility or strength.
Seita added, “The reason why heating and beating is so effective is because it changes the internal structure of the material, allowing control over its properties. That’s why it’s still in use after thousands of years.”
One of the major drawbacks of today’s 3D printing techniques is the inability to control the internal structure in the same way, which explains why so much post-production modification is required.
“We’re trying to come up with ways to restore some of that structural engineering capability without the need for heating and beating, which would in turn help reduce costs. If you can control the properties you want in metals, you can leverage the greener aspects of 3D printing.”
Dr. Matteo Seita from Cambridge’s Department of Engineering
New Metal 3D Printing process – Programming Structural Modifications
Seita developed a new ‘recipe’ for metal 3D printing process with colleagues in Singapore, Switzerland, Finland, and Australia, allowing a high degree of control over the internal structure of the material as it is melted by a laser.
The researchers can programme the properties of the end material by controlling how the material solidifies after melting and the amount of heat generated during the process. Metals are typically designed to be strong and tough so that they can be used safely in structural applications. 3D-printed metals are naturally strong, but they are also brittle.
The researchers developed a strategy that gives them complete control over both strength and toughness by triggering a controlled reconfiguration of the microstructure when the 3D-printed metal part is placed in a furnace at a low temperature. Their method employs traditional laser-based 3D printing technologies, but with a minor modification to the process.
“We found that the laser can be used as a ‘microscopic hammer’ to harden the metal during 3D printing,” said Seita. “However, melting the metal a second time with the same laser relaxes the metal’s structure, allowing the structural reconfiguration to take place when the part is placed in the furnace.”
Their theoretically designed and experimentally validated 3D printed steel was made with alternating regions of strong and tough material, making its performance comparable to steel made through heating and beating.
Seita concluded, “We think this method could help reduce the costs of metal 3D printing, which could in turn improve the sustainability of the metal manufacturing industry. In the near future, we also hope to be able to bypass the low-temperature treatment in the furnace, further reducing the number of steps required before using 3D printed parts in engineering applications.”
Nanyang Technological University, the Agency for Science, Technology and Research (A*STAR), the Paul Scherrer Institute, the VTT Technical Research Centre of Finland, and the Australian Nuclear Science and Technology Organisation were among the researchers on the team. Matteo Seita is a St John’s College, Cambridge, Fellow.
