Traditionally, printing Inconel 718, especially for complex shapes with curved thin walls, has been challenging due to the material’s properties and the limitations of additive manufacturing (AM) processes. However, through a dedicated material development project, Wayland has successfully addressed and overcome these obstacles.
Uniform, thin, curved walls printed in Inconel 718 are a particular problem for metal AM processes for several reasons linked to the nature of the processes (laser and eBeam) and the material itself. Defects such as warping, swelling or distortion can emerge for such thin parts, especially with eBeam processes due to large thermal gradients resulting from elevated temperature processing.
The NeuBeam process, as implemented on the Calibur3 system, has demonstrated its ability to address these challenges with specific beam parameters and controlling the speed of the beam. This project has been able to develop an optimised build strategy for these complex curved thin-wall parts that controls the temperature of the build to achieve the required density.
Added Bonus — Minimal Post Processing with NeuBeam
Parts produced with the NeuBeam process do not require support structures and benefit from hassle-free de-powdering because the process does not require hard pre-sintering of the powder bed, which eliminates the formation of a sintered powder “cake” around the parts. As a result, unused powder remains free-flowing and can be quickly and easily removed from even complex, thin-walled geometries, streamlining post-processing and reducing time and effort compared to traditional electron beam systems. Calibur3 can build the parts successfully and cost effectively.
A further challenge this project sought to overcome was that of surface finish. The requirement was to achieve a surface finish at least as good as the surface finish achieved by laser metal AM. Anyone that knows existing AM processes, knows that the eBeam processes tend to produce a rougher surface finish because the powder particle size for eBeam processes is larger than for laser processes. Typically, for eBeam AM particle size is in the region of 45-100 microns, while for laser AM particle size is typically 15-45 microns.
For this project with Inconel 718, Wayland developed process parameters that have allowed the deployment of finer Inconel 718 powder within the 15-45 microns range on the Calibur3. This was enabled by the capabilities of NeuBeam with its Active Charge Neutralisation (ACN) together with the ability to process multiple meltpools simultaneously, in this case 50 of them. All with no ‘smoke events.’ The required surface finish has been achieved.
Important to state at this point, that this is a proof-of-concept development project. However, the results have exceeded expectations for all involved. The optimised NeuBeam parameters for the Inconel 718 parts have shown what is possible with the material, the complex part build and the surface finish.