# Comparison of the Wear of Toroidal and Spherical Cutters in Milling and the Impact of Corrosion
## 4 Conclusions  
**Evaluation and comparison of milling cutter wear**  
The main purpose of the study was to analyze and compare the degree of wear of toroidal milling cutters and ball end milling cutters in the context of processing five types of surfaces, with the tool axis inclined at three distinct angles (15\({}^{\circ}\), 35\({}^{\circ}\), and 55\({}^{\circ}\)). The research was based on experimental results, focusing exclusively on comparing tool wear, without analyzing the specific stages of wear, and taking into account only the number of machined  
Figure 13: Graphical representation of measured values. \begin{table}
\begin{tabular}{c c c c c} \hline
**Type of Cutter** & **Tilt Angle** & **Initial Wear Area** & **Wear Area After 5 Years** & **Percentage of Wear** \\  & & **[mm\({}^{2}\)]** & **[mm\({}^{2}\)]** & **Increase** \\ \hline Toroidal milling 1 & 15\({}^{\circ}\) & 0.27127 & 0.38006 & 40.1 \\ \hline Toroidal milling 2 & 35\({}^{\circ}\) & 0.44564 & 0.57925 & 29.98 \\ \hline Toroidal milling 3 & 55\({}^{\circ}\) & 0.48123 & 0.79088 & 64.34 \\ \hline Spherical milling 1 & 15\({}^{\circ}\) & 0.27160 & 0.31419 & 15.68 \\ Spherical milling 2 & 35\({}^{\circ}\) & 0.35776 & 0.43704 & 22.16 \\ \hline Spherical milling 3 & 55\({}^{\circ}\) & 1.02941 & 1.14944 & 11.66 \\ \hline \end{tabular}
\end{table} 
Table 3: Comparison between the measured values of initial wear and tear after 5 years. parts. Tool wear was quantitatively assessed by measurements made with the MM1-200 microscope, which provided accurate tool degradation data after machining 45 surfaces with each cutter. The results obtained highlighted the following:  
1. **Differences in the degree of wear**: Ball end cutters experienced a 38% higher degree of wear compared to toroidal cutters, indicating a superior strength of toroidal cutters under the tested conditions. 2. **Influence of tilt angle**: The highest wear for both types of cutters was observed at a tilt angle of 55\({}^{\circ}\). At this angle, the wear difference between the ball end mill and the toroidal cutter was 113%, which underlines the significant impact of the angle on tool performance. 3. **Minimal wear**: The lowest wear was recorded in both types of cutters during machining at an angle of 15\({}^{\circ}\), suggesting that the smaller angles reduce mechanical stresses on the tool. **Influence of corrosion on tool wear**  
A secondary objective of the study was to investigate the effects of corrosion on the wear of the milling cutters analyzed, especially under conditions of prolonged inactivity. Based on practical observations, tool wear has been found to include a preliminary stage of corrosive wear, which occurs before advanced mechanical wear, especially in the case of stored tools. Although mechanical wear remains the main factor in tool degradation, the effects of corrosion cannot be neglected, as they influence the geometric stability of the tool edge and, implicitly, its durability. In the context of corrosion analysis, it was observed that tools used intensively and then stored for a long term (five years) in unfavorable environmental conditions have the following characteristics:  
1. **Stagnation of wear**: Regardless of the initial degree of wear, after the period of inactivity, there has been no significant progress in mechanical wear, this being replaced by the effects of corrosion. 2. **Corrosion wear variation**: The increase in wear due to corrosion ranged from 11.66% to 64.34%, with an average of 30.64%. Notably, the milling cutter with the highest initial mechanical wear exhibited the least increase in corrosive wear, indicating a complex interaction between mechanical and corrosive wear. 3. **Impact of inactivity**: Prolonged inactivity has a significant impact on the condition of the tool edge, especially in the case of tools with special specifications, which are often stored for future use in complex machining.