## 3 Results  
### Analysis of Surface Quality and Parameter Effects  
The experimental results obtained from the ball burnishing process on Ti grade 2 material revealed significant variations in surface quality across different parameter combinations (Table 2). Surface roughness measurements showed Ra values ranging from 0.306 \(\upmu\)m to 0.727 \(\upmu\)m and Rz values from 2.397 \(\upmu\)m to 5.339 \(\upmu\)m. The optimal surface quality was achieved under MQL conditions with a burnishing force of 200 N, feed rate of 0.5 mm/min, and four passes, resulting in the lowest Ra value of 0.306 \(\upmu\)m. In contrast, the highest Ra value of 0.727 \(\upmu\)m was observed under dry conditions with minimal force (50 N), low feed rate (0.5 mm/min), and a single pass, indicating the substantial impact of processing parameters on surface quality outcomes. The data in Table 2 clearly demonstrate the superior performance of MQL conditions over dry processing in achieving better surface finishes. This is attributed to the enhanced \begin{table}
\begin{tabular}{c c c c c c c c} \hline \multirow{2}{*}{**Experiments**} & \multicolumn{6}{c}{**Parameters**} \\ \cline{2-7}  & \multirow{2}{*}{**Environment**} & **Force** & **Feed Rate** & **Number of** & & & \\  & & **(N)** & **(mm/min)** & **Passes** & & & \\ \hline  
\hline \end{tabular}
\end{table} 
Table 2: Parameters and results after the burnishing process. lubrication and cooling effects provided by MQL, which facilitate more effective plastic deformation of the surface layers. The significant difference in surface quality between MQL and dry conditions aligns with the findings of [PERSON] et al. [3], who reported similar improvements in surface finish with MQL in machining processes. The influence of burnishing force is evident, with higher forces generally leading to improved surface quality. Under MQL conditions, a burnishing force of 200 N consistently produced the best results, supporting the notion that increased force enhances the plastic deformation of surface asperities, as noted by [PERSON] et al. [21]. This trend is particularly pronounced when combined with multiple passes, improving surface finish by progressively refining the surface texture. The number of passes also plays a critical role, with four passes yielding the lowest Ra values. This cumulative improvement effect is consistent with the work of [PERSON] and [PERSON] [5], who demonstrated the benefits of repeated processing in enhancing surface hardness and reducing roughness. The interaction between feed rate and other parameters reveals that lower feed rates (0.5 mm/min) generally produce better results when combined with higher forces and multiple passes, suggesting that slower processing speeds allow for more thorough surface deformation and refinement. The main effects plot for S/N ratios in Figure 5 highlights the influence of different processing parameters on the surface roughness of Ti grade 2. The analysis indicates that the processing environment is the most significant factor affecting surface quality, with MQL consistently outperforming dry conditions. This is attributed to the enhanced lubrication and cooling effects provided by MQL, which facilitate more effective plastic deformation of the surface layers, leading to a smoother finish. This finding aligns with the research by [PERSON] et al. [11], who demonstrated the benefits of MQL in improving surface integrity during machining processes. The burnishing force also shows a positive correlation with surface quality improvement. Higher forces, particularly 200 N, generally yield better results by promoting more effective plastic deformation of the surface asperities. This trend is supported by the findings of [PERSON] et al. [25], who found that increased burnishing force enhances surface finish in titanium alloys. Feed rate and the number of passes further influence surface roughness, with lower feed rates and multiple passes contributing to improved surface quality.