Unravelling the dependency of dross formations in metal additively manufactured channels as a function of channel diameter and inclination angle

In recent years, the non-destructive characterisation via X-ray computed tomography of internal features, often produced with novel manufacturing methods, has gained increasing attention. Reducing the rate of defects during the production of internal features is of particular interest since post-processing steps are highly cumbersome, or removal of defects is, in many cases, even impossible for complex channels or bores. However, it is not sufficient to characterise the defects solely, but their root causes need to be understood in depth to allow for a-priori compensation approaches fostering first-time right part production. To achieve this, it is imperative to fully understand the connections and influences between the different factors, to enable the creation of versatile and scalable correction and compensation approaches. Within this scope, this work presents a characterisation of additively manufactured internal channels, focussing on dross defects encountered in overhang regions of the channel and their dependency as a function of a broad range of channel diameters and inclination angles. The extraction of the required information from the channels is based on cross-sectional images along the channel's axis of the reconstructed 3D volume, obtained with high-resolution X-ray computed tomography. With the data obtained through an analysis algorithm presented in an earlier publication, it is possible to extract characteristic identifiers that can be used to calculate potential compensations counteracting the defects emerging during the printing. With the aid of these identifiers, it is possible to chart out general trends of the channel defects as a function of channel diameter and inclination angle. Therefore, the results allow to identify parameters where certain defects remain almost constant for a variation of the channel diameter.