SIM-AM 2025

Geometry-dependent spot sequences for complex geometries in electron beam powder bed fusion

  • Kupfer, Tobias (Friedrich-Alexander-Universität)
  • Körner, Carolin (Friedrich-Alexander-Universität)
  • Markl, Matthias (Friedrich-Alexander-Universität)

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In electron-beam powder bed fusion, parts are created by selectively melting powder layers using a high-power electron beam. Electromagnetic lenses deflect the beam at velocities reaching kilometers per second, enabling spot melting strategies. Spot melting localizes energy input to a degree unachievable with traditional line-based scan strategies, for example allowing for tailored microstructures, such as equiaxed or columnar grains in specific areas of the layer [1]. Each layer may consist up to hundreds of thousands of spots, leading to a nearly infinite number of possibilities to create a melt order, the so-called spot melting sequence. In the literature, the most commonly described routines for determining a spot melting sequence are (I) random selection or converting line-based melting by using a point skip to (II) pattern melting. Both routines create spot sequences without taking the geometry into account and therefore do not fully exploit the potential of spot melting. We present a graph-based routine to create geometry-dependent spot melting sequences for complex geometries. This approach ensures a homogeneous energy distribution across a complex geometry while maintaining a narrow jump distance distribution, adhering to machine restrictions. It supports various contour concepts to improve the surface quality. The proposed routine can be applied to entire parts, generating machine-ready build files from the CAD model within minutes to hours, even for parts composed of millions to hundreds of millions of individual spots. [1] Plotkowski, A., Ferguson, J., Stump, B., Halsey, W., Paquit, V., Joslin, C., Babu, S.S., Marquez Rossy, A., Kirka, M.M., Dehoff, R.R.: A stochastic scan strategy for grain structure control in complex geometries using electron beam powder bed fusion. Additive Manufacturing 46, 102092 (2021) https://doi.org/10.1016/j.addma.2021.102092