By Mark Norfolk on Tuesday, January 19th, 2016
The other day we were on a conference call with a potential client. Well-schooled in ‘traditional’ 3D printing of metals, the client asked “Tell me about how you control the melt pool.” This is a common misunderstanding about our process. The fundamental distinguishing characteristic of UAM, in comparison to other metallic additive manufacturing technologies, is that it is a solid-state welding process – meaning that melting of metals does not occur – with all of the attendant impact of high temperatures on material properties. If we are not melting, then how do we create a bond?
Without interference of the oxides that coat them, metals naturally want to bond to each other. Our ultrasonic process uses a scrubbing action to break off the layer of oxide that lies on every metal surface in our atmosphere. With a little bit of pressure and a little bit of heat, the metals form a solid state joining. Below is a great video showing from Rice University two small metal wires in a vacuum. As they are brought together you can watch then ‘snap’ together in a solid state bond.
By using ultasonics to weld thin layers of foil layer upon layer, we are able to 3D print solid metal parts with full density. Ultrasound does create a small amount of heat, but in aluminum alloys we see peak temperatures under 250°F which is well below the melting temperature of any metal.
The low temperature bond enables unique UAM capabilities: