## 1 Introduction
Despite growing interest in post-processing techniques for 3D-printed metals, particularly in the context of Industry 4.0 [18], there remains a notable research gap concerning the application of MAF to AM-produced parts, especially in the case of nickel-based superalloys like Inconel 939. This alloy, known for its exceptional mechanical strength at elevated temperatures, high oxidation resistance, and excellent thermal fatigue performance, is widely used in the aerospace and energy sectors--particularly in turbine blades, engine nozzles, thermal shields, and jet engine components. These applications demand stringent surface quality standards, making reliable post-processing critical. Yet, MAF studies targeting Inconel 939 in the context of AM remain scarce, with few attempts to tailor tool design, process parameters, or media composition to the alloy's unique metallurgical and geometrical characteristics. Advancing research in this area is essential to unlock the full potential of MAF as a viable finishing method for high-performance, additively manufactured components. The present study undertakes an experimental validation of the effectiveness of MAF for finishing the surfaces of Inconel 939 samples additively manufactured using the LPBF technique. Special emphasis was placed on optimizing key process parameters such as eccentricity, processing time, and rotational speed, alongside both qualitative and quantitative analyses of the surface topography outcomes. A novel aspect of this research is the implementation of preliminary vibratory machining combined with MAF featuring planetary kinematics--specifically, the application of an eccentric motion of the sample within a ferromagnetic abrasive medium. Unlikeconventional configurations in which the tool or sample moves in simple linear or rotary paths without additional degrees of freedom, this setup introduced an adjustable eccentricity as a parameter, controlling both the intensity and nature of abrasive-surface interactions. This innovation enabled dynamic modulation of the working gap during rotation, influencing the formation and behavior of the flexible \"tool\" composed of magnetic abrasive particles. Importantly, the study focuses on Inconel 939--a high-performance nickel-based superalloy that poses significant machining challenges due to its high strength, thermal stability, and oxidation resistance. Despite its widespread application in the aerospace and energy sectors, systematic studies on the post-processing of LPBF-fabricated Inconel 939 components remain scarce. In particular, the use of magnetic abrasive finishing for this alloy is largely unexplored, which further highlights the novelty and industrial relevance of the presented research. As a result, greater uniformity in abrasive action over the sample surface was achieved--an especially critical factor when dealing with variable geometries and the high porosity typically associated with 3D-printed Inconel 939. This approach aligns with the broader trend toward hybrid and adaptive MAF kinematic systems, which are better suited to the post-processing demands of additively manufactured components. At the same time, it presents a practical proposal for both industrial implementation and laboratory research.