## 1 Introduction  
In recent years, there has been a rapid development in additive manufacturing technologies, particularly metal 3D printing methods such as LPBF (laser powder bed fusion) and EBM (Electron Beam Melting), which enable the fabrication of components with high geometrical complexity and optimized material functionality [1]. However, one of the main limitations to their industrial implementation remains the high surface roughness characteristic of the as-built condition following the layer-by-layer construction process [2, 3]. In the context of components made from hard-to-machine alloys such as Inconel 939, conventional finishing techniques often prove insufficient or even unfeasible--particularly when dealing with geometrically complex structures or areas with limited accessibility. Against this background, magnetic abrasive finishing (MAF) emerges as a promising technology for precision surface finishing, offering selective and flexible control over the material removal process, even in hardly accessible zones. Numerous reports in the literature demonstrate the effectiveness of this method, both in reducing surface roughness parameters such as Ra and in improving the functional and mechanical properties of the processed surfaces [4]. Despite the growing body of work on MAF, further exploration is necessary to tailor the process to specific material systems and additive manufacturing outputs. [PERSON] et al. [5] focused on the development of an innovative surface finishing method for additively manufactured copper structures. A major challenge in metal 3D printing technologies, particularly EBM, is the inherently high surface roughness, which in the as-built state can reach Ra values as high as 35 \(\upmu\)m. Such roughness significantly limits the applicability of these components in demanding industrial sectors where surface finish quality is critical--such as in vacuum systems, cooling devices, or microfluidic structures. The authors proposed a finishing method based on the use of magnetorheological fluid, which enables effective polishing of both external and hard-to-access internal surfaces. The process is driven by a dynamic magnetic field that manipulates the motion of an abrasive suspension, allowing for selective and precise material removal. Experimental results showed a substantial improvement in surface quality, with Ra reduced to approximately 4 \(\upmu\)m, corresponding to an 88% reduction. Building on this, other studies have investigated the underlying mechanisms of material removal in MAF, aiming to optimize abrasive selection and process dynamics for various materials and geometries. [PERSON] et al. [6] presented an experimental investigation into the material removal mechanisms from the surface of 316L stainless steel components manufactured via Selective Laser Melting (SLM) and subsequently finished using magnetic abrasive finishing (MAF). The study focused on the influence of magnetic particle size and the type of abrasive medium--comparing conventional and magnetic abrasives. It was demonstrated that larger magnetic particles (acting as rigid tools) promoted material removal from peak areas of the surface, while smaller, more flexible particles more effectively accessed surface valleys. It was established that magnetic abrasives removed material more slowly but resulted in a more uniform and smoother finish, whereas conventional abrasives removed more material but generated surfaces with higher roughness and more irregular topographies. Surface topography parameter analysis revealed that surfaces processed with magnetic abrasives exhibited higher skewness and lower kurtosis, indicating a dominance of valleys and a lower incidence of sharp peaks. The study confirms that MAF enables the controlled surface treatment of SLM structures, offering process adaptability depending on the desired outcome--either increased material removal or improved surface finish quality.