AM 101: Ultrasonic Additive Manufacturing
This solid-state additive process makes it possible to produce parts from dissimilar metals. The company more recently introduced a much smaller machine.
What Is Ultrasonic Additive Manufacturing (UAM)?
The additive process that grew out of ultrasonic welding provides an efficient way to produce complex work, including parts with embedded components and even parts made from dissimilar metals.
Ultrasonic additive manufacturing (UAM), a process developed by Fabrisonic, builds metal workpieces by fusing and stacking metal strips. The work is done on a hybrid machine tool able to CNC mill the workpiece as the additive build proceeds. Building by stacking metal strips enables a fast build rate, making large parts practical.
The Fabrisonic ultrasonic additive manufacturing machine has a work envelope of 6 × 6 × 3 feet. Developed by Fabrisonic, the machine is built by Ultra Tech Machinery, another Ohio Company.
How Does It Work?
In UAM, material is not melted, but instead joined through ultrasonic welding. This welding uses high-frequency vibration to join surfaces while the metal remains solid. By welding layer upon layer upon layer in this way, the process builds solid parts.
While under high-frequency ultrasonic vibration and constant pressure, the ultrasonic motion breaks up oxides through friction, enabling the direct contact of metal on metal.
Image credit: FabrisoniThis process, with minimal heating, results in a solid state atomic bond or weld between the thin metal tape and the substrate. Multiple layers are welded together one after the other to build up height.
This process is repeated until a solid part has been built. Then CNC contour milling can be used to obtain required tolerances and optimal surface finish for the parts.
Why Use Ultrasonic Additive Manufacturing?
The solid-state process makes it easy to embed sensors or other objects into solid parts. The build is simply paused as the embedded object is added, then the build continues to seal it inside.
The solid-state weld also provides a reliable way to join dissimilar metals without creating brittle metallurgy. For all metals, the bonding temperature is below their melting temperature. A hard metal outer surface could be built onto a structure made from a lighter metal to provide a part with both durability and light weight. Or, two very different metals — titanium and aluminum, say — could be combined in shuffled layers to create a structure that mixes the properties of both.
This technology combines the usefulness of additive and subtractive manufacturing, allowing parts with complex geometries and internal passageways to be built. The fine dimensional accuracy and smooth surfaces of the parts built with UAM and machining prove the possibilities of hybrid manufacturing.