Jens Bauer, Karlsruhe Institute of Technology (KIT)

Three-dimensional printers are expanding their repertoire every day. Now researchers around the world are using the technology to manufacture structural steel and metal components.

Also known as additive manufacturing, 3D printing creates solid objects by successively piling material layers, one on top of the next, from a printer head. While plastic has been used as a medium in 3D printing for years, metal is less commonbecause it requires more heat to melt as well as shielding from atmospheric gases that can alter its composition.

Arup, headquartered in London, recently announced that it has developed a method to 3D print complex structural steel components for construction projects in a manner that reduces material cost and waste. Salomé Galjaard, a senior designer in Arup’s Amsterdam office, notes that the process can achieve the fluid shapes and complex geometries that architects often desire—and more structurally efficient components. “It could be a great source of inspiration and could result in completely different building types,” she says. “Your imagination is really the limitation with this.”


Arup funded the research and worked with several additive manufacturing partners to prototype a structural connection from maraging steel—a type of high-strength steel that is easy to print. Distinct from conventional geometric connections, the node has an organic shape because it uses only enough material to carry the determined loads. “It just gives you what you need,” Galjaard says.

Arup hopes to use the component on a project soon. “It would be great to work with an actual client and designer and see what we can come up with,” Galjaard says.

The European Space Agency (ESA) along with the European Commission is also researching 3D printing structural components—but for use in space. It recently launched an initiative called AMAZE, or Additive Manufacturing Aiming Towards Zero Waste & Efficient Production of High-Tech Metal Products. “We want to build the best quality metal products ever made,” says David Jarvis, ESA’s head of new materials and energy research, in a press release.

AMAZE ultimately wants to put the first 3D metal printer on the International Space Station. Astronauts could then manufacture tools, objects, and even satellites on demand, saving time and money by eliminating the need to launch heavy equipment loads.

A conventionally machined valve (left) and a 3D printed valve (right).
European Space Agency (ESA) A conventionally machined valve (left) and a 3D printed valve (right).

In an Engineering & Technology video, Jarvis notes that one of the challenges of printing metal in space is weightlessness. Indeed, the heated, molten metal could literally escape the printer bed and float away. To prevent this, Jarvis says, a robotic system will rise to capture the liquid metal through the natural force of surface tension before it slips away.

The technology may result in new product types. “We can remove some of the design constraints that we’ve been faced with … machining and casting and forging, which are the standard techniques for metal work,” Jarvis says in the video.

AMAZE is building factories for 3D metal printing in Germany, Italy, Norway, and the United Kingdom, along with a full supply chain. The team predicts that 3D printed metal will find its way into aircraft wings, jet engines, automotive systems, and other applications.

European Space Agency (ESA) and Foster + Partners

While Arup and the ESA are printing structural metal products, researchers at Karlsruhe Institute of Technology (KIT), in Germany, are using 3D laser lithography to print micro-trusses and micro-shell structures from ceramic material, which is then coated by aluminum oxide for increased strength. These micro-scale products are less dense than water, yet stronger on a strength-to-weight ratio than some forms of steel.

Jens Bauer, Karlsruhe Institute of Technology (KIT)

“It has been a longstanding effort to create materials with low density but high strength,” the researchers wrote in a paper published in the Proceedings of the National Academy of Sciences. After studying the composition of wood and bone, which generally have high tensile strength because of their porous composition, the team developed honeycomb-shaped microstructures that achieved the research objectives: They were lighter than 1,000 kilogram per cubic meter (62.4 pounds per cubic foot), or the density of water, and could withstand 280 megapascals (40,610 pounds per square inch), making it stronger than some forms of steel.

Jens Bauer, Karlsruhe Institute of Technology (KIT)

Although computer simulations had indicated that such materials could be created, the tools to develop them at the “scale of a human hair” only came to being recently, according to an article from The Conversation. But KIT researchers used a new laser system from Nanoscribe, a spin-off company of KIT, to make it a reality.

Lead researcher Jens Bauer told The Conversation that “this is the first experimental proof that such materials can exist.” Nanoscribe’s system is currently limited to objects that are tens of micrometers in size.

Despite additive manufacturing’s advances and potential for fabricating structural metal products, Arup’s Galjaard doesn’t expect the technology to replace traditional manufacturing soon. “It’s fantastic and it’s beautiful, but it’s not the solution for everything,” she says.