## 1 Introduction
Experimental validation confirmed that the new method outperforms conventional MRF-based fluids, with roughness reduction exceeding 67% and improved surface hydrophobicity, evidenced by an increase in the contact angle from 24.08\({}^{\circ}\) to 61.18\({}^{\circ}\). Surface topography observations confirmed the effective removal of typical SLA defects--such as scan lines and pores--without introducing additional surface damage. A novel method for finishing hard-to-reach internal cavities of additively manufactured parts fabricated by SLM was developed by [PERSON] et al. [10]. The authors proposed the BERMP (bias external rotating magnetic pole) technique, enhanced with vibrations. This method employed spherical steel grit (SG) abrasives, which were mobilized under the influence of a rotating magnetic field and superimposed vibrations. Both the experimental and simulation results showed that vibrations significantly increased the abrasive coverage across the machining zone, enhancing process efficiency and surface quality. Analysis of variance (ANOVA) and response surface methodology (RSM) were used to evaluate the influence of key process parameters--including the working gap, magnetic pole rotational speed, vibration frequency, and amplitude--on the final surface roughness Ra. Optimal conditions were determined as a 1 mm working gap, 800 rpm, 15 Hz frequency, and 0.2 mm amplitude, under which Ra was reduced from 12.60 \(\upmu\)m to 1.25 \(\upmu\)m (a 90% reduction). Microscopic observations confirmed a significant decrease in surface irregularities and the effective removal of unmelted metal particles. Additionally, it was shown that excessive abrasive volume disrupted the process region, whereas insufficient abrasives led to uneven surface finishing. The application of hybrid surface processing--combining magnetic abrasive finishing (MAF) and heat treatment (HT)--for Inconel 718 superalloy components fabricated via LPBF has been shown to enhance tensile strength. [PERSON] et al. [11] demonstrated that an optimized sequence of these processes significantly improves both surface roughness and mechanical properties. The most favorable results were obtained for samples that underwent homogenization followed by MAF and aging, achieving a tensile strength of 1334 MPa and an elongation of 22.9%. The study emphasizes that MAF is effective even for complex geometries and that its combination with HT enables the reduction of residual stresses and the microstructural inhomogeneities characteristic of LPBF-fabricated components. In parallel, advancements in tool design have further expanded the capabilities of MAF-based methods, enabling the efficient post-processing of intricate internal geometries in additively manufactured components. [PERSON] et al. [12] introduced a novel method for finishing the internal surfaces of AISI 316L stainless steel tubes produced via LPBF using a magnetically driven internal finishing tool (MDIF). This method enabled substantial surface roughness improvement--from an initial Ra of 11.6 \(\upmu\)m to 0.385 \(\upmu\)m in pointwise experiments and 0.808 \(\upmu\)m in sectional trials, all within a short processing time (<2 min). Compared with conventional MAF, MDIF demonstrated superior performance in both surface quality and material removal efficiency. A key advantage of MDIF is its ability to precisely guide the tool through hard-to-access geometries via interaction with an external magnet. The theoretical model based on an Abbott-Firestone curve confirmed that the increased material removal observed in 3D-printed components results from the elimination of surface-specific defects such as stair stepping, balling, and loosely bound particles. This technique shows strong potential for finishing geometrically complex channels in additively manufactured structures. Beyond internal surface treatment, other studies have emphasized the importance of pre-processing and parameter optimization to fully leverage MAF for finishing high-performance alloys fabricated by additive manufacturing. [PERSON] et al.