In metal additive manufacturing, many ways of doing the process involve a lot of heat. To learn more about a different technology, we spoke to Mark Norfolk, President and CEO of Fabrisonic.
Fabrisonic uses a low-temperature technology based on ultrasonic welding. Most parts never get above 200 F. “From a metallurgy perspective, that’s everything,” said Norfolk. “We’re using thin foils of metal, and ultrasonically welding those layer by layer to create a part.”
Ultrasonic welding is not new—the process has been around since the 60’s. “We’ve taken that 1960’s tech and put 10 kW into it, to print a part in almost any metal,” said Norfolk.
The high power allows the technology to print parts up to 6 by 6 feet, at 10-15 cu.in/hour, which doesn’t sound really exciting, but considering powder beds print about 1-2 cu.in/hour, it’s a step in the right direction.
3D Printing Without Melting
“We’re 100% dense,” said Norfolk, referring of course to the metal parts produced by Fabrisonic. The unique process allows for a particularly unique benefit: the solid-state, low-temp nature allows for the embedding of different materials. “Layer one, Aluminum; layer two, tantalum; layer 3, nickel—all in the same part and all 100% dense. The bond is metal to metal. You can embed electronics, thermocouples, strain gauges in the part. 1/3 of our work is health monitoring. For example, a fiber optic strain sensor in a large part allows us to measure the health history in the part,” said Norfolk of this unique ability.
It’s a promising concept: active electronics can be buried inside solid metal, where they can’t be damaged. For example, high power switching components can be buried in metal for advanced cooling, surrounded by water jackets.
However, Norfolk’s company has more than one innovation up their sleeve. “The one thing we do a little different is we try to minimize the amount of 3D printing. 3D printing is slow and expensive. We’ll take a plate the height of the sensor, then build overtop of the sensor, so we’re only printing what is above the point where the technology is needed,” he explained.
Additive is great for adding little features, but bulk material can be slower. Why build where you don’t have to?
Heat Exchangers
The process is ideal for thermally conductive materials: does this mean heat exchanger applications? “Heat exchangers are half our business,” confirmed Norfolk. “We actually just built a heat exchanger almost 5’x3’. It’s about getting the thermal components integrated with the structure, getting rid of part count and weight. We just worked with NASA JPL, and we went through a whole qualifying process for a heat exchanger. Our was 30% lighter, had 40% better thermal performance, and it was done in 9 days.”
Anisotropy
Norfolk said that the process does not change the metal. “1 micron North and South of the interface we see some grain refinement, but we’re not driving precipitation reactions, we’re not driving grain growth,” he elaborated. Norfolk is an alumnus of the welding engineering program at Ohio State—he likes to geek out on metallurgy.
“If we did our process in a vacuum, we would have no issues with anisotropy,” he mused. “As we’re welding in open air with no shielding environment as we're welding, we do get a little bit of oxide inclusion. So, in the z-axis we lose about 10 % of strength.”
In x and y directions, the strength is whatever the incoming material is. In z, the parts take a 10% hit. This can be mitigated through heat treat, but if the 10% reduction in strength is within specifications, it’s often not worth it.
“Our biggest industry is aerospace. We're just now getting some heavy interest from oil and gas and even some automotive, which is kind of surprising--you know, given their volumes—but there's some interesting sweet spots there,” Norfolk said.
For more videos on the latest additive manufacturing technology, check out How 3D Printing Wins in Metal Part Manufacturing.