Melt Pool Analysis in DED-LB/M with Freeform Beam Shaping based on High-Speed Imaging

Additive manufacturing has rapidly grown towards widespread industrial use. However, there is a limit using high power laser sources, as material evaporates in the center zone of the Gaussian intensity profile. Furthermore, control of solidification parameters is crucial to ensure the part quality. Therefore, innovative beam shape sources are being explored, such as static profiles, stepwise adaptable profiles and freeform beam shapes. The aim of this work is therefore to explore high-speed optical monitoring data in directed energy deposition using freeform beam shapes. Manufactured single melt tracks are used to explore different beam shapes in terms of laser-material interaction, energy density distribution, melt pool stability and solidification. The evaluation focuses on static geometric, static intensity distribution and dynamic intensity changes in between a sequence of images. The evaluation of high-speed camera data allows deriving metrics to evaluate the melt pool stability using the standard deviation, the laser-material interaction zone using a long-term intensity distribution, and the intensity gradient to evaluate the solidification. The melt track width derived from monitoring data matches well the physical measurements of the melt track.