## 3 Results
### Visual Representation and Comparison of Wear and Friction Predictions  
After selecting the best ANN models using a GA, these models were employed for the visual representation and comparison of real wear and friction values with the predicted wear and friction values. Figures 8-10 present the surface plots depicting the wear and friction values for force intervals ranging from 0 to 1 N and velocity intervals spanning from 4 to 12 mm/s. These visualizations offer a comprehensive representation of the variation in wear and friction across the three surface types--polished, glazed, and ground--highlighting the distinct characteristics of each surface. The surface plots illustrate the predicted and known values of wear (left plots) and friction (right plots) under varyingconditions of velocity and normal force. In each figure, the predicted values are represented as continuous surfaces while the known values are marked with red points, providing a comparative visualization of model performance. For the wear rates prediction plots (positioned left in Figures 8 and 9), the surface exhibits nonlinear behavior, with wear values increasing significantly as the normal force approaches its upper limit (near 1) and velocity increases. The red points align closely with  
Figure 8: Polished surface—predicted wear rate and friction coefficient by ANN models using a GA vs. real values of wear rate and friction coefficient. Figure 10: Ground surface—predicted wear rate and friction coefficient by ANN models using a GA vs. real values of wear rate and friction coefficient. Figure 9: Glazed surface—predicted wear rate and friction coefficient by ANN models using a GA vs. real values of wear rate and friction coefficient. the predicted surface, highlighting the model's accuracy in capturing the observed data. This suggests that wear rates are more pronounced under higher normal loads and velocity conditions for both finishing techniques (polished and glazed), with a maximal value of 14 mm\({}^{3}\)/m. In the COF prediction plot (positioned right in Figures 8 and 9), the COF values also demonstrate nonlinear behavior, with variations dependent on the interplay between normal load and velocity. The COF values decrease with increasing velocity and normal force but plateau at higher levels, indicating a potential stabilization of friction under specific conditions. What is characteristic of these processed surfaces is that the maximum coefficient of friction is approximately 0.44 and occurs at the lowest sliding velocity and the smallest applied force. The predictions shown in Figures 8 and 9 are fully consistent with the obtained values of the experimental tribological results. In the wear rate prediction plot (positioned left in Figure 10), the surface exhibits significant variability with sharp transitions, reflecting the nonlinear relationship between wear rate, velocity, and normal load. Wear rate values generally increase with velocity and normal force, with notable peaks in specific regions, indicating heightened wear sensitivity under certain conditions. The red points align well with the surface, particularly in critical regions, showcasing the model's ability to capture complex patterns effectively. Compared to the previous two surfaces, the wear rate trend of the ground surface is more gradual. Depending on the sliding velocity, the increase in wear remains within a narrow range for all values of normal load, which is corroborated by the obtained experimental results. The COF prediction plot (positioned right in Figure 10) illustrates a smoother surface compared to the wear prediction but still captures subtle variations influenced by the input parameters. The COF values decrease gradually with normal force and velocity, stabilizing in specific ranges. The close proximity of red markers to the surface highlights the model's precision in approximating observed friction values.