Electron beam processes are quite well known in the welding industry, for example, but what about metal additive manufacturing?
For this video, we spoke to Oscar Angervall, product manager for the Arcam EBM Spectra H machine.
The Spectra H Machine for metal additive manufacturing uses an electron beam gun to sinter together layers of powder material, similar to an SLS or SLM process. However, the Spectra H has a few features which make it unique.
The machine creates a vacuum within the build chamber. This is essential to an electron beam process, because the electrons would otherwise collide with molecules of the air. The vacuum also prevents the material from oxidizing, which can compromise the strength of the part.
The machine is also capable of maintaining temperatures of up to 1000 C, which makes it possible to build with materials like aluminides and cermets, as well as other crack-prone metals.
During a build, the entire build chamber is under vacuum and at temperature. Inside, a tungsten filament is superheated, producing a cloud of electrons that are electromagnetically accelerated to almost half the speed of light. Magnetic coils control and focus the beam of electrons, similar to the technology behind an old tube television, except with 6 kW of power. Instead of directing the beam at a phosphor-coated screen, it’s directed at the powder bed.
This process supports crack-prone materials which are sensitive to rapid heating and cooling, thanks to the high temperature maintained in the build chamber. However, the materials required for this process must be pure, necessitating a validated supply chain and rigorous testing.
According to the GE website, parts produced with this machine have similar properties to wrought parts and better than cast parts. However, like many additive processes, the surface finish is rough and bumpy, sometimes necessitating post-processing, such as for mating surfaces, holes, and other features.
For more information on GE Additive, check out HP, GE Additive and EOS Lead 3D Printing Revenue Growth for 2017.