## 3 Results and Discussion  
### Surface Topography  
Figure 1 illustrates the relationship between the \(Sa\) parameter and feed rate \(f\). The obtained \(Sa\) parameter values for different feed rates exhibit significant variation depending on the type of cutting tool used and the cutting speed. Only for a feed rate of \(f=0.025\) mm/rev do the recorded results show similar values. For the other feed rates applied, significant differences exist between the individual cutting tools. It is noteworthy that the highest \(Sa\) parameter values on surfaces machined with the ceramic 6160 tool were recorded for feed rates of \(f=0.025\) mm/rev, \(f=0.055\) mm/rev and \(f=0.07\) mm/rev. A similar trend was observed for surfaces machined with the carbide S205 tool, where the highest \(Sa\) values were recorded for feed rates of \(f=0.025\) mm/rev, \(f=0.04\) mm/rev, and \(f=0.07\) mm/rev. Lower roughness parameter \(Sa\) values for surfaces machined with the S205 carbide tools were achieved at a cutting speed of \(v_{c}=200\) m/min, while for surfaces machined with the ceramic 6160 tools, lower \(Sa\) values were obtained at \(v_{c}=250\) m/min. Therefore, increasing the cutting speed for both types of cutting tool materials positively affects the roughness parameter \(Sa\). A similar conclusion was reached by [PERSON], [PERSON] and [PERSON]. [PERSON] et al. [27] machined Inconel 625 alloy using carbide tools with MQL (minimum quantity lubrication), cryogenic cooling, and CryoMQL. [PERSON] et al. [28] have machined Inconel 718 alloy using emulsion and CO\({}_{2}\). [PERSON] et al. [29] conducted studies using AISI 1045 steel and found that increasing the cutting speed reduces the built-up edge (BUE) on the cutting edge, positively impacting the surface quality of the machined part. Comparing the obtained \(Sa\) parameter values after turning with S205 carbide tools and 6160 ceramic tools at the same cutting speed \(v_{c}=200\) m/min, it can be observed that the S205 carbide tools produce surfaces with lower \(Sa\) roughness parameter values (Figure 1). This is particularly evident for the highest applied feed rate of \(f=0.07\) mm/rev, where the \(Sa\) parameter obtained with the ceramic 6160 tool is more than twice as high compared to the value achieved with the S205 carbide tool. The reduction of the \(Sa\) parameter was obtained by [PERSON] et al. [30] by using ultrasonic assisted machining. Compared to conventional machining, the \(Sa\) parameter was three times smaller. Figures 2-5 present isometric maps of the machined surfaces. Characteristic turning marks were observed on all analyzed surfaces. The surfaces obtained with a feed rate of \(f=0.025\) mm/rev exhibit similar \(Sa\) parameter values, but their isometric images differ (Figure 2a-d). High ridges were observed on surfaces machined with both S205 and 6160 tools. The difference between these surfaces is that on the S205-machined surfaces,  
Figure 1: The impact of feed \(f\) on the variability of roughness parameter \(Sa\). distinct areas of high ridges can be identified (marked on figures by red circle), whereas on the 6160-machined surfaces, individual ridges appear sporadically (marked on figures by white circle). Additionally, on the surface machined at a cutting speed of \(v_{c}\) = 200 m/min (Figure 2c), a higher frequency of high ridges was observed compared to the surface machined at \(v_{c}\) = 250 m/min (Figure 2d). From a functional standpoint, the S205-machined surfaces exhibit a more favorable topography. The isolated high ridges on the 6160-machined surfaces reduce contact between interacting surfaces [31]. Surfaces machined with a feed rate of \(f\) = 0.04 mm/rev, similar to those machined at \(f\) = 0.025 mm/rev, also exhibit characteristic turning marks (Figure 3a-d). However, these marks are more pronounced on surfaces machined with S205 carbide tools, whereas on surfaces machined with 6160 ceramic tools, they appear more blurred.