From the Blog

3D Printing Metal at Room Temperature with UAM

weld
Fusion based welding processes have been a pillar of metals manufacturing for decades.  Since the inception of metal 3D printing, innovators have focused on fusion based welding processes; such as laser, electron beam, and even arc.  Fusion based welding process, though still common today, present many complications for modern manufacturers.  Phase changes, metallurgical interactions, and thermally induced residual stress are major difficulties that come with any form of fusion welding. Thus, major hurdles in developing metal additive manufacturing have revolved around preventing issues inherent to fusion welding processes.
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Figure 1 – SonicLayer 7200 with 6’x6’x3′ work envelope

Ultrasonic Additive Manufacturing (UAM) was developed to 3D print metal with solid state; therefore eliminating obstacles that come with fusion welding.  By leveraging a low temperature welding process with integrated CNC machining, UAM can create complex components that have distinctive features and attributes not possible with fusion based welding: One key aspect that makes UAM unique is that the joining is accomplished in the solid state, meaning no melting occurs during the process.  In fact, temperatures at the weld have been measured to be below 150° C in aluminums.
Figure 2 - Fiber Optic cable embedded in Aluminum

Figure 2 – Fiber Optic cable embedded in Aluminum

Figure 3 - Layers of copper and aluminum welded in the solid state

Figure 3 – Layers of copper and aluminum welded in the solid state

This is important for three reasons. First, by avoiding melting and staying below the transformation temperatures of most metals, the inherent mechanical properties of the incoming feedstock are not reduced or altered. For instance, precipitation hardened alloys are not at temperature long enough to cause any meaningful precipitation reaction, thus allowing the bonding of high strength aerospace alloys without any loss of mechanical strength.  The second benefit is the solid state nature for welding dissimilar metals. Typical fusion based process, when used on dissimilar metals, result in mechanically inferior properties as the resultant solidification structure is some type of intermetallic glass. Third, the solid state nature of the weld allows bonding at such low temperatures that electronics and other temperature sensitive devices can be built into the metal structure without damage.
Figure 4 - Illustration of the UAM welding head. Two transducers vibrate a solid steel horn left to right.

Figure 4 – Illustration of the UAM welding head. Two transducers vibrate a solid steel horn left to right.

The UAM process involves building solid metal objects through ultrasonically welding a succession of metal tapes into a three-dimensional shape, with periodic machining operations to create the detailed shape of the resultant objects. High-frequency (typically 20,000 hertz) ultrasonic vibrations are locally applied to metal foil materials, held together under pressure, to create a weld. The vibrations of the transducer are transmitted to the disk-shaped welding horn, which in turn creates an ultrasonic solid-state weld between the thin metal tape and a base plate. The continuous rolling of the horn over the plate welds the entire tape to the plate. Successive layers are welded together to build up height. This process is then repeated until a solid component has been created. CNC contour milling is then used to achieve required tolerances and surface finish.  See a video of the process here. To learn more about UAM, visit www.fabrisonic.com or contact info@fabrisonic.com See Mark at FABTECH 2016 during session F53:Design and 3D Merging Technologies for Additive Manufacturing. Learn more here.   [x_author title=”About the Author”]

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