## 3 Results and Discussion
### Discussion  
It should be emphasized that the proposed sequence of surface machining, including vibratory finishing and MAF, results in a more pronounced reduction of the Rz roughness parameter compared to the Ra parameter. This phenomenon can be explained by the specific nature of the elastic tool used in the process, which--due to its compliance--more effectively eliminates topographical extremes, such as deep valleys and sharp peaks, rather than small deviations within the microstructure. Importantly, the effectiveness of this process is inversely proportional to the eccentricity value--an excessively large eccentricity may introduce overly intense and uncoordinated interactions, leading to deterioration in the uniformity of the surface finish. Despite these complex interactions, the developed machining configuration enabled a significant final effect--a reduction in the Ra parameter from an initial value of 5.6 \(\upmu\)m (measured before vibratory finishing) to 0.81 \(\upmu\)m after a total machining time of 4 h and 20 min. This considerable improvement in surface quality is highly competitive with the results achieved using other post-processing methods, such as shot peening, which, although effective in enhancing mechanical properties, does not always yield comparable surface topography improvements [25]. In the course of analyzing the obtained results, particular attention should be paid to the significant impact of the geometrical asymmetry of the samples on the MAF finishing process. Since the tested samples were not axisymmetric in shape, their interaction with the elastic abrasive tool underwent considerable fluctuations over time. The samples rotated freely about their own axis, and the direction and speed of this motion were determined by dynamically changing conditions in the working zone. Key factors included local gradients in the magnetic field, the irregular concentration and distribution of abrasive grains, and variability in the sample's angle of incidence relative to the tool during successive stages of rotation. Although the coefficient of determination (R\({}^{2}\)) obtained for the regression model describing the relationship between the surface roughness parameters and the process variables may appear relatively low, it should not be interpreted as a shortcoming of the model. Instead, it reflects the inherent complexity and variability of the magnetic abrasive finishing (MAF) process when applied to geometrically complex, additively manufactured parts. The non-axially symmetric geometry of the workpieces combined with planetary kinematics introduces dynamic interactions that inherently limit the predictability of individual outcomes through simple linear models. Importantly, despite the moderate R\({}^{2}\) values, the results of the F-test demonstrated a statistically significant effect of eccentricity on surface roughness, indicating that this parameter exerts a dominant influence on the finishing outcome. This finding underscores the robustness of the statistical approach and validates the relevance of eccentricity as a key driver of surface integrity in the context of MAF applied to LPBF-manufactured Inconel 939 components. This configuration led to non-stationary but more adaptive tool-surface interaction. The non-uniformity of contact resulted in differences in local contact pressure and the penetration depth of abrasive grains, which could affect both the rate of material removal and the quality of the resulting surface. To contextualize the effectiveness of the developed MAF process, a comparative analysis with other state-of-the-art surface finishing techniques was conducted (see Table 7). Although the obtained surface roughness (Ra \(\approx\) 0.81 \(\upmu\)m) after 20 min of processing is slightly higher than what can be achieved with thermal methods such as laser polishing (Ra < 0.1 \(\upmu\)m within seconds), MAF offers several notable advantages.