Fabrisonic LLC, Columbus, Ohio, USA, is partnering with TGV Rockets, Norman, Oklahoma, to develop its Ultrasonic Additive Manufacturing (UAM) process into equipment that can repair damage to spacecrafts, with a goal of eventually manufacturing in orbit. UAM is an AM process that utilises thin metal foils as feedstock material.
The most obvious use for Additive Manufacturing in space is for repairs. Currently, there are 27,000 pieces of space debris large enough to be tracked orbiting Earth. Moving at over 17,000 mph, any one of these can lance a hole in space structures – even flecks of paint can cause serious damage on impact. A small piece of debris can puncture a hole in a spacecraft which would require immediate repair to stabilise the situation and, hopefully, allow the mission to continue.
Long term, though, the real focus for Fabrisonic in space is construction. Currently, spacecrafts are built mainly to support the loads experienced during launch, but, once in space, most spacecraft experience almost no real structural loading. If engineers can develop ways to manufacture in space, then material efficiency could be vastly increased. An additional benefit is that far larger structures than will fit in launch vehicles can be built; by launching raw materials and then manufacturing in space, needed structures can be built without having compromise designs just for launch.
There are many benefits for UAM in space over welding, including lower power consumption and a lack of filler required. Capable of joining a wide range of metals, including 6061 and 7075, two of the most popular aluminium alloys for space, UAM is a solid-state process that maintains 97% of the original feedstock’s properties and does not cause a heat-affected zone or require post-process stress relieving.
On a prior NASA SBIR project, Fabrisonic’s 20 kHz sonotrode was reconfigured and miniaturised into its 30 kHz device. The goal was to shrink the UAM equipment to further reduce system weight and power usage. Not only did the company illustrate that its equipment could shrink to meet NASA requirements, but the resulting designs have also been commercialised into the SonicLayer 1200 UAM machine.
The next step is freeing Fabrisonic’s UAM print head from its current CNC platform. The goal of this SBIR project is to develop alternative motion systems for its welding tool. Having a flexible motion system, like a robot arm, could allow UAM to access and repair damage on spacecraft and could also free the process from the restrictions of a build envelope here on Earth. Although the company’s SonicLayer 7200 already has a very large footprint at 72 x 72 x 63 inches, a robotic UAM device would dramatically increase the potential applications for this technique.
A low temperature, low energy, welding process on the end of a large motion system enables the possibility of constructing large structures in orbit. For instance, a densely packed load of beams could be launched into orbit, after which an autonomous system could arrange the beams into structures using UAM to link together these elements with metal AM at each joint.