“Mantis” AM System for Spacecraft Uses Induction for Deposition

At a recent reveal event in the company’s home city of Mesa, Arizona, large-format metal additive manufacturing startup Rosotics debuted its new “Mantis” system for 3D printing large pressurized vessel parts such as spacecraft tank, rocket stage and fuselage sections. Two innovations distinguish the company’s machine, both of which are evident in the photo below.

One innovation is the method of melting the material. Rosotics’ directed energy deposition system is wire-fed, but rather than a laser, it uses what the company terms “Rapid Induction Printing” to deposit material. The wire is fed through an electromagnetic coil generating heat in the metal via eddy currents.

This leads to several benefits, says co-founder and CEO Christian LaRosa. Two metal AM safety hazards, metal powder and lasers, are both avoided. Meanwhile, power consumption is less, to the extent that the machine can be run off a standard industrial electrical connection. “We are able to do this from a simple 240-volt outlet,” he says.

The other innovation is in the machine design. The Mantis system prints building-size metal structures, but it does not require a frame or gantry as large as these parts. The travel of the robot-like deposition arm is coordinated with a rotary work surface on which the cylindrical part grows.

This rotary work surface is a modular component, changed out according to the size of the part being built, and today might accommodate parts up to 9 meters (30 feet) in diameter. Providing for rotary feed in this way leaves the motion of the print arm itself entirely free for controlling the metal deposition angle as the part turns, including printing unsupported overhangs.

LaRosa says, “If you can get those degrees of freedom from the system, you can begin to combine multiple components together, [such as] a tank section with an integrated dome taper at the top.” These are otherwise separate pieces. “Figuring out how to bring the large pieces together and get a friction stir weld between them — that is an entire assembly stage we can now eliminate by changing the process.”

Importantly, the reliance on eddy currents does not preclude non-conductive metals, he says. Aluminum is an important metal for the applications the company targets. In the case of this metal, rather than heating the feedstock directly, the induction can be used to heat an inner sleeve that in turn heats the metal. The Mantis has thus proven effective for printing with both steel and aluminum at a controlled deposition rate of 15 kg per hour. The modular system can also be configured to let up to three heads print the same part simultaneously, for a controlled rate of 50 kg per hour.

Production will begin on the first commercial Mantis systems later this year. To ensure affordability and allow Rosotics access for upgrading machines in the field, the company is not selling the system outright, but instead marketing it through a hardware-as-a-service model involving an entry fee and a recurring subscription price.