## 3 Results
### Analysis of Surface Quality and Parameter Effects
The interaction between these parameters suggests that slower processing speeds allow for more thorough surface deformation and refinement, especially when combined with higher forces and  
Figure 5: Main effects graph associated with S/N ratios concerning surface roughness value. MQL conditions. This cumulative effect is consistent with the work of [PERSON] et al. [40], who reported that multiple passes enhance surface hardness and reduce roughness. The interaction plot for Ra in Figure 6 provides a detailed view of the complex relationships between the process parameters and their combined effects on surface roughness. The analysis reveals that the processing environment, particularly the use of MQL, significantly enhances the effectiveness of higher burnishing forces. Under MQL conditions, applying a 200 N force consistently results in superior surface finishes, highlighting the synergistic effect of lubrication and force in reducing surface roughness. This observation is supported by the findings of [PERSON] et al. [4], who noted similar improvements in surface quality with optimized lubrication and force parameters in titanium machining. The interaction between feed rate and the number of passes also plays a crucial role in determining surface quality. When combined with multiple passes, lower feed rates lead to a more refined surface finish. This is likely due to the increased contact time and repeated deformation of the surface, which allows for a more uniform and smoother finish. This cumulative effect is consistent with the research by [PERSON] and [PERSON] [12], who demonstrated the benefits of optimizing feed rate and pass number in achieving desirable surface characteristics in metalworking processes. Furthermore, the interaction plot suggests that, while higher forces generally improve surface quality, their effectiveness is maximized under MQL conditions and with multiple passes. This indicates that the benefits of increased force are best realized when supported by adequate lubrication and repeated processing, as also noted by [PERSON] and [PERSON] [17] in their study on surface roughness prediction in machining. The 3D plot in Figure 7 illustrates the effects of various ball burnishing parameters on the surface roughness of Ti grade 2 under dry and MQL conditions. The axes represent burnishing force (N), feed rate (mm/min), and the number of passes, while the symbol size indicates surface roughness (Ra) values. The plot reveals that MQL conditions (blue spheres) generally result in lower Ra values compared to dry conditions (red spheres), highlighting the effectiveness of MQL in enhancing surface quality. This observation aligns with the work of [PERSON] et al. [9], who reported similar improvements in surface integrity under MQL conditions for titanium alloys. Notably, the optimal surface finish is achieved with a burnishing force of 200 N, a feed rate of 0.5 mm/min, and four passes under MQL, as indicated by the darkest color on the scale. This suggests that higher forces and multiple passes, particularly under MQL, synergistically improve surface integrity by facilitating effective plastic deformation and lubrication. This synergistic effect can be attributed to the  
Figure 6: Interaction graph of parameters for S/N ratio evaluated for the surface roughness value. enhanced plastic deformation facilitated by the combined action of force and lubrication, as noted by [PERSON] and [PERSON] [15] in their multiphysics modeling study of surface integrity in titanium alloys. The surface morphology of the burnished samples reveals significant differences between the MQL and dry conditions. As shown in Figure 8a, the MQL-processed surface exhibits a smoother and more homogeneous texture with fewer scratches and micro-indentations, corresponding to a lower surface roughness (Ra = 0.306 \(\upmu\)m). This improvement can be attributed to the effective lubrication and cooling mechanism of MQL, where the lubricant forms a thin protective film between the tool and workpiece interface, as supported by [PERSON] et al.