A father and son team in the US have invented a liquid metal 3D printing machine that could represent a significant transformation in additive manufacturing. By Grove Potter.

A breakthrough idea five years ago by Zack Vader, then a 19-year-old student at the University of Buffalo, has resulted in the creation of a machine that prints three-dimensional objects using liquid metal. Today his company – Vader Systems – is innovating and building the machines in a factory in Getzville, New York State. Zack’s father Scott, a mechanical engineer, is the CEO, while  Zack is the chief technology officer. His mother, Pat Roche, is controller.

The machine is so novel it could represent a quantum leap in the ability to print three-dimensional objects in metal. Other metal printers exist, but most use a process of laying down powdered metal and melting it with a laser or electron beam. In that process, some particles of the powder do not get melted, creating weakened spots.

Several manufacturers have begun to voice their interest in the Vader machine, with one automotive parts maker expressing an intention to eventually buy at least 50 of them. A printer with multiple nozzles could cost more than $1m.

Continued collaboration

The University of Buffalo has continued to work with the Vader team, acting as a source of intellectual assistance, grants and personnel for the start-up as it transforms from a promising idea into an established business. The Vaders were working on their invention in the basement of their home in Amherst when Scott decided to reach out to the University for help.

“We were working alone in our basement and tackling some pretty deep technical problems,” says Scott. “We knocked at the door of the University and they welcomed us in. They set up an impressive first meeting with faculty experts the University of Buffalo, and they said, ‘What are you trying to do? What are your problems and how can we help?’”

The Vaders now have three faculty advisors; in addition, they are part of the START-UP NY tax-free entrepreneurial program, and have won grants from the University’s Center for Industrial Effectiveness (UB TCIE), its Center for Advanced Biomedical and Bioengineering Technology (UB CAT) grant, and a National Grid grant through the University. Morever, and perhaps most importantly, Scott believes that access to university students for internships has helped the company grow. Vader Systems has already hired three mechanical engineering graduates.

“This is what makes really good young engineers, to go from the theory and being able to mix in an internship with a local industry,” says Scott. “They realise that the lab they took is something a company really needs.”

Inspiration born from disappointment

Now 24 years old, Zack first started focusing on metal printing when his plans to hire a company to produce 3D-printed parts for a microturbine generator were stymied. No company could print the parts that he needed, so he decided to make his own metal printer. The breakthrough came when he had the idea to expose molten metal in a confined chamber with an orifice to a pulsed magnetic field. The transient field induces a pressure with the metal that ejects a droplet. That was the key to making droplets of liquid metal eject from a nozzle.

Edward P Furlani PhD, a professor at the University of Buffalo’s Chemical and Biological Engineering and Electrical Engineering departments, said that Vader’s process mimics drop-on-demand inkjet printing and is based on the principles of magnetohydrodynamics – the manipulation of conductive fluids using a magnetic field. In Vader’s device, an electrically pulsed magnetic field permeates liquid metal in an ejection chamber and creates circulating electrical currents. These currents interact with the magnetic field to produce a pressure that squeezes a droplet out of the ejector nozzle.

“It’s a transformative technology,” says Furlani. “It’s very exciting interdisciplinary engineering. I think its application base will continue to broaden and expand for the foreseeable future.”

Ciprian N Ionita, PhD, a research assistant professor in the Biomedical Engineering Department (a joint venture between of the School of Engineering and Applied Sciences and the Jacobs School of Medicine and Biomedical Sciences at the University) foresees the Vader Systems printer ultimately printing out custom stents and other surgical devices right in the hospital.

“This is a game changer,” says Professor Ionita. “The metal powder used in the current metal printing processes is a contaminant that is difficult to clean up and can be toxic inside the body. The Vader printer also will be valuable making custom knee and hip replacements.”

Cheaper, faster, better

The third University of Buffalo advisor providing support to the Vaders, Chi Zhou, is an assistant professor in the Industrial Systems Engineering Department and a 3D printing expert. He says that another advantage of the Vader system is that it is “much, much cheaper” than using powered metal.

“I can see at this stage that it can complement traditional metal printing,” says Professor Zhou. “But later, maybe 10 years later, it can dominate the metal printing market because it can print better quality, cheaper and faster.

Professor Zhou has helped write original open-source software to control the printer.

“If they want to add functionality, we can. We have the source code,” he says.

One of the most fascinating qualities of a 3D printer is that a complex part is just as cheap to make as a simple part. This is the opposite of traditional manufacturing, which makes the machines very attractive to companies that are engaged in making large numbers complex parts.

“Complexity does not add cost,” says Zack.

Steel printing on the horizon

On a Vader machine, a strand of aluminium is fed into a heat element that melts it at 750 degC. The liquefied metal is then passed on to a ceramic tube with a sub-millimetre orifice, forming an ejection chamber. A magnetic coil that surrounds the tube delivers a short-lived electrical pulse to create a pressure within the tube, which as a result ejects a droplet of liquid metal through the orifice. The ejected droplet is projected downward onto a heated platform that is then manoeuvred to create solid 3D shapes based on layer-by-layer deposition and the coalescence of the droplets.

Zack says plans are to modify the device, adding more nozzles to make it faster. Eventually the machines will be able to melt and print steel at 1,400 deg.C. As the machine evolves, the Vaders plan to expand their operation into an assembly-line manufacturing facility.

Possible applications for the device run the gamut. Scott says that the automotive industry may be interested in making parts that are now solid metal into hollow and honeycombed structures. The hollow parts would be lighter, stronger and much cheaper. As for the tiny generator that Zack was hoping to print, it may emerge again someday, now that the technology to make it is advancing.

“That’s just been put on the shelf for a while,” he says.