## 4 Conclusions  
* Upon reviewing the graphs generated from this study's experimental plan, it was observed that an increase in the feed led to higher surface roughness values, which negatively impacted surface quality. Conversely, increasing the tool's cutting-edge angle resulted in lower surface roughness values, improving surface quality. In the experiments, it was observed that there was an improvement in surface roughness that was in line with the general trend with the increase in spindle speed. It was also determined that surface roughness values that did not comply with the general trend increased by combining some processing parameters. In addition to the harmony of the tool-part-machine tool trio in processing operations, the correct determination of the chip removal method is necessary. Therefore, each of the processing parameters is important. Lower surface roughness can be obtained by optimizing processing parameters. This way, the lowest surface quality can be obtained quickly with low power consumption. For these reasons, it can also be said that some of the processing parameters in this study are not the most accurate working parameters for the tool-part-machine tool trio. As a result, it was determined that when the correct processing parameters were selected, the final demand and the best surface roughness value could be obtained. * When examining Figures 4-6, which used a constant depth of cut of 0.5 mm, the average surface roughness values based on cutting-edge angles of 70\({}^{\circ}\), 80\({}^{\circ}\), and 90\({}^{\circ}\) were measured to be 2.282 \(\upmu\)m, 1.769 \(\upmu\)m, and 1.228 \(\upmu\)m, respectively. Similarly, Figures 7-9 were analyzed under the same depth of cut of 0.5 mm but with varying feeds of 0.155, 0.088, and 0.028 mm/rev. The corresponding average surface roughness values were 2.056 \(\upmu\)m in Figure 7, 1.667 \(\upmu\)m in Figure 8, and 1.228 \(\upmu\)m in Figure 9. When Figures 10-12 are examined, the lowest surface roughness values are measured as 2.282 \(\upmu\)m (CEA 70\({}^{\circ}\), 630 rpm, 0.028 mm/rev), 1.785 \(\upmu\)m (CEA 80\({}^{\circ}\), 1250 rpm, 0.028 mm/rev), and 1.228 \(\upmu\)m (CEA 90\({}^{\circ}\), 480 rpm, 0.028 mm/rev), respectively. These data show that the lowest surface roughness value is measured as 1.228 \(\upmu\)m in Figure 12 due to the experimental studies conducted on the constant spindle speed-surface roughness relationship and other variables. These experimental parameters also confirm the general approach that the lowest spindle speed, lowest feed, and cutting tool angle are 90\({}^{\circ}\) and that the lowest feed value among these values will give lower surface roughness when some machining parameters are selected, as in Figure 11 (1250 rpm, 0.155 mm/rev, 2.680 \(\upmu\)m) and Figure 12 (1250 rpm, 0.155 mm/rev, 2.057 \(\upmu\)m), increasing the spindle speed can lower surface roughness for a fixed feed value. The difference between the surface roughness values in the last two figures and the lowest surface roughness values in Figure 10 is slight. Therefore, this selection can be helpful when machining at high operating spindle speeds is required. * In conclusion, the optimal parameters for achieving the lowest average surface roughness (1.228 \(\upmu\)m) in these nine experimental setups were a depth of cut of 0.5 mm, a cutting-edge angle of 90\({}^{\circ}\), a spindle speed of 480 rpm, and a feed of 0.028 mm/rev. * In the article, only HSS was used as the tool material for processing. Different tools were not added to this study. For this reason, an explanation about this subject was added to the Conclusion Section. As a future study, a more meaningful evaluation can be made about the surface roughness of Ms58 brass material by using the parameters in this study, working experimentally with different tool materials, and evaluating the results obtained together with all the study results. * The article's authors preferred turning the outer cylindrical surface as a machining process since the processed part is cylindrical.