What Exactly Makes Xact Metal’s Metal 3D Printing So Cheap?
Michael Molitch-Hou posted on July 25, 2017 | | 8962 views

This year’s RAPID + TCT show was abuzz with news about Desktop Metal, an exciting new metal 3D printing startup that has already raked in millions of investor dollars. However, Desktop Metal was not the only company to showcase novel techniques for metal additive manufacturing (AM). In fact, there were several firms at the show that displayed their unique methods for 3D printing metal, including 3DEO, Admatec and Markforged.

The Xact Metal XM200 metal 3D printer. (Image courtesy of Xact Metal.)
The Xact Metal XM200 metal 3D printer. (Image courtesy of Xact Metal.)

While all promise the ability to 3D print metal parts at lower price points, only one startup at the event unveiled a platform that promises to deliver the same parts one sees with typical powder bed fusion systems, like those from EOS, at such a low cost. Xact Metal is a Pennsylvania-based company that has developed a powder bed fusion metal 3D printer that it plans to sell for just $120,000.

ENGINEERING.com spoke to the company’s CEO, Juan Mario Gomez, and CTO, Matt Woods, to learn more.

From Multi-Metal to Low-Cost Metal 3D Printing

While attending Pennsylvania State University and working at the school’s CIMP-3D AM lab, Woods came up with the idea for a 3D printer capable of melding multiple metals in the same build. However, to prove out his concept, Woods couldn’t exactly tinker with the prestigious lab’s million-dollar equipment. Instead, he was left to his own devices.

Woods was able to obtain bits of funding here and there through grants from Penn State, as well as incubators and Pennsylvania’s Ben Franklin Technology Partners program. “When I finished my degree, I decided to work on the technology full time at Innovation Park at Penn State. I began recruiting some fellow students and friends that I knew to be very talented in what they do, which is either building things or designing things or manufacturing,” Woods explained.

In the process, he and his team came up with a new approach to laser metal 3D printing.

“We began prototyping our own metal powder bed fusion system—basically made on a shoestring budget,” Woods said. “Through that, we had developed this system that allowed us to bring down the cost of a metal system, but at the same time have the performance characteristics of a high-end system. That was kind of the genesis of what we now use as our platform that allows us to deliver a laser beam in a slightly different way than is currently done in the industry.”

As Woods began to transition the technology away from multi-metal 3D printing and toward low-cost metal AM, he began working with Gomez, a manufacturing veteran who had spent over 25 years working with GE. It took just about nine months between the time that Gomez entered the picture and Xact Metal was able to debut its flagship XM200 system at RAPID + TCT this past May.

Cost Constraints Drive Innovation

It was actually the cost constraints of Xact Metal’s development process that allowed Woods and his team to invent the company’s novel method for metal 3D printing. Gomez explained, “He bought a used binder jet printer, took it all apart and, on that foundation, he built a new system that replaces the galvanometer mirrors typically found in a powder bed fusion process with an X-Y gantry system.”

A diagram of the laser sintering process using galvanometer mirrors. (Image courtesy of CustomPartNet.)
A diagram of the laser sintering process using galvanometer mirrors. (Image courtesy of CustomPartNet.)

In traditional laser-based powder bed fusion 3D printers, at least one powerful laser is directed at a series of galvanometer mirrors, which rotate quickly to bounce the beam at a bed of metal powder, fusing the particles together. Although the mirrors are small, the mirror systems themselves are bulky, heavy and expensive to buy and maintain.

Xact Metal has done away with the galvos and replaced them with what the company calls the “Xact Core” an X-Y gantry system, which sees lighter, less expensive mirrors mounted onto a gantry that moves them in the X- and Y-axes above the powder bed.

The Xact Metal system, in which the scan head is always at a right angle to the powderbed. (Image courtesy of Xact Metal.)
The Xact Metal system, in which the scan head is always at a right angle to the powderbed. (Image courtesy of Xact Metal.)

“The problem that we had is that because they are very, very small, the galvo mirrors move very, very fast,” Gomez said. “They can move up to seven meters per second on a point-to-point translation. But the real performance needed for fusing requires moving the mirrors at about 800 to 1,500 millimeters per second. We knew that if we were able to match the fusing equivalent speeds of galvos, we would be in the ballpark of an equivalent printer.

“Several people have thought about replacing the galvanometer mirrors, but could not make it work. We had to apply a variety of tricks with the printer—how it’s setup, its performance, how to move the mirrors around and control the whole architecture—to be able to invent this and make it work. It sounds simple, but it wasn’t so simple to get there,” Gomez explained.

Xact Metal’s original proof-of-concept machine could scan the printbed at a sluggish 100 millimeter per second; however, with some proprietary innovations, for which the company has filed some patents, Xact Metal was able to increase the speed up to 1.5 meters per second. “We still use mirrors, but instead of rotating them, we translate the mirrors and keep the gantry as lightweight as possible to move it as fast as possible,” Woods said.

Cheaper and Better?

By replacing the galvanometer mirrors with mirrors that translate about the X- and Y-axes, the startup was able to create the $120,000 XM200. With a build volume of 5 in x 5 in x 5 in (127 mm x 127 mm x 127 mm), the XM200 uses a 250W fiber laser.

For a comparison, Concept Laser’s research-focused Mlab cusing machine has a price of roughly $191,000, a build volume of 2 in x 2 in x 3.2 in (50 mm x 50 mm x 80 mm), and relies on a 100W laser. EOS’s smallest machine, the EOS M 100, has a base price of roughly $233,000, a build volume of Ø3.9 in x 3.7 in (Ø100 mm x 95 mm), and uses a 200 W laser.

The innovations Xact Metal developed made it not only possible to drop the price dramatically but also to bring about improvements in the consistency of the metal 3D printing process. Some of these improvements were inspired by work Woods had performed as an intern with SpaceX.

“I was involved with the AM team at SpaceX, so I was directly involved with the small group of individuals that were actively building out SpaceX’s AM capability: pretty much all of the printing involved with the SuperDraco thrusters, the main oxidizer valve, all components that we were building out to go on flight,” Woods said.“We were really just proving out the different types of machines that we had there and working on quantifying the quality of the parts.”

While at SpaceX, Woods was involved in a study that explored how part location on the printbed influenced the physical properties of the part. According to Woods, galvanometer systems reflect the beam at an indirect angle to the printbed, which can change the weld properties of the powder and spot size of the laser.

With the Xact Metal platform, however, the scan head is always orthogonal (at a right angle) to the printbed, meaning that the laser beam always hits the printbed head on. To describe the effect this has, Woods likened the process to pointing a flashlight at a wall. Pointed directly at a wall, a flashlight will have a perfectly circular shape. As that light is moved along the wall at an angle, the spot becomes more elliptical.

For a game of Ghosts in the Graveyard, this has no impact on the fun being had. In metal 3D printing, it introduces variability to the build process that can alter the overall physical properties of a part. “[Other manufacturers] do their best to account for and compensate for the angle of the laser as it is directed toward the powder bed, but, fundamentally, our angles are not changing,” Woods said. “It’s constant across the whole build plate, which means constant weld properties and tighter control over the actual spot size and just the beam profile in general.”

Parts 3D printed by the Xact Metal process. (Image courtesy of Xact Metal.)
Parts 3D printed by the Xact Metal process. (Image courtesy of Xact Metal.)

Another advantage that Xact’s system brings to the process is the ability to easily control the diameter of the laser beam on the powder, known as the laser’s “spot size.” A larger spot size can provide better deposition rates, making it possible to fuse material more quickly, while a smaller spot size enables finer resolution, higher detail printing. Changing between these two in a single print would allow a build to take advantage of both of these benefits.

“With a galvo system, you need some pretty interesting optical control to change the spot size, so it’s not very common in powder bed fusion,” Woods said. “But with our system, we actually can vary the spot size without adding additional hardware or changes whatsoever.”

To do so, the Xact Metal platform takes advantage of the inherent need to raise and lower the build platform to control the spot size. By raising the bed, it’s possible to increase the spot size. By lowering it, the spot size shrinks.

“It’s just a matter of controlling the toolpath to change the spot size depending on if you want to have a faster infill and be able to lay down more material to get less build time,” Woods explained. “At the same time, if you want to have smaller features, you can have a smaller spot size and really dial in those small details.”

Coming This Fall

Gomez said that he anticipates the XM200 to be ready for shipment this September. It’s not often that a company can go from proof of concept to shipped product in a year’s time, but, given Gomez’s experience at GE, it seems doable.

Of his experience, Gomez said, “It’s been a good complement to Matt [Woods]’s work—for everything from manufacturing to finding vendors to the [material requirements planning] to managing the compliance of the printer for different regulations,” Gomez said. “The laser will meet regulations in the U.S. under the FDA. We will have UL compliance for electrical safety, CE compliance in Europe and country code compliance around the world. We’ve also been setting up our go-to-market strategy, pricing points and the vendor strategy. All of that is coming together very nicely.”

While the XM200 will be best suited toward R&D labs and universities, the company already has more in the works. Gomez and Woods pointed out that the platform Xact has developed is highly scalable, in terms of the size of the machine and the ability to add more lasers to the gantry. To demonstrate this fact, the company is already in the process of developing a midsize 3D printer, which will be unveiled at formnext this November.

When the show hits, we may just learn if Xact Metal brings the industry a new type of powder bed fusion that can compete with the stalwarts of metal 3D printing. If so, the technology may be ready for a big shift.

To learn more about Xact Metal, visit the company’s website.


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