## 4 Model Prediction Results and Analysis
### Effect of Cutting Parameters on Surface Roughness  
An analysis of the response relationship existing between the average surface roughness and the cutting speed, feed rate, and depth of cut was carried out. The three three-dimensional plots as shown in Figure 16a-c represent roughness response plots under dry cutting conditions.  
When the feed rate falls below 0.1 mm, the surface of AISI 304 stainless steel machined by micro-groove tool has a smoother surface finish. According to the previous research reports, the temperature [31] and energy distribution [32] of the micro-groove tool during the cutting process are improved, as a result of which the cutting force and friction coefficient is reduced. The cutting force and friction coefficient cause tool vibration, which is one of the leading reasons for the roughness increase [44]. Therefore, the friction coefficient decreases, thus improving the average surface roughness. The micro-groove design proposed in this paper is based on the temperature field morphology of finite element method, and combines the workpiece material and cutting parameters for the design of the tool rake surface shape, for which the machined surface roughness can be improved in a certain range of parameters. As reported in the literature [30], the cutting tools with different rake tool surface structures exert different influences on the surface quality, [PERSON] explained that because the improved  
Figure 16: Surface roughness as a function of cutting parameters, (a) _ap_ is a constant equal to 1.5 mm, (b) \(v\) is a constant equal to 120 m/min, (c) \(f\) is a constant equal to 0.08 mm.  
Figure 15: Main effects plot for surface roughness.  
-take face structure can reduce the energy in the cutting process, reducing the cutting force is conducive to improving the quality of the machined surface within certain cutting parameters.  
On the contrary, when the feed rate is in excess of 0.1 mm, the surface roughness deteriorates while the performance of the traditional turning tool is improved. As indicated by [PERSON] [33], the cutting tools with satisfactory test results may not perform well under different machining conditions. The micro-groove tool having a lower surface roughness in the low feed machining process is shown in Figure 16. The finishing machining is mostly realized in the low feed machining process [26]. In this sense, the micro-groove tool is suitable for AISI 304 stainless steel parts which require a higher surface finish.  
As clearly revealed by Figure 16b, the feed rate has a notable effect on the surface roughness. A high feed rate will generate helicoids on the machined surface, and increasing the feed rate will result in not only a decline in dynamic stability during the cutting process but also a deterioration in surface quality. The theoretical relationship between the average surface roughness and the feed rate also demonstrates that the average surface roughness increases with the square of the feed rate when the tip radius of the tool remains unchanged. These results conform to prior studies [7]. In the three parameters, the change to feed rate is observed to exert the most significant effect on the surface roughness. On the other hand, [PERSON] [11] conducted an analysis of the impact caused by cutting parameters on the machining of 304 stainless steel by Pareto ANOVA, which led to the discovery that the cutting speed and feed have only an insignificant effect on the surface roughness. As demonstrated by the variance analysis of the surface roughness of machined stainless steel conducted by [PERSON] [45], the impact of the feed on the surface roughness is about 80.71% and the cutting depth is only 2.99%. The effect exerted by other cutting parameters on the surface roughness is not significant. From Figure 16b,c, it can be seen that the surface roughness of the workpiece declines gradually before increasing with the rise in the depth of cut, with the change being insignificant. The effect of the cutting speed on surface roughness is limited as well.