## 2 Materials and Methods  
The tests were conducted on cylindrical samples with an outer diameter of 132 mm and a length of 129 mm. The samples were made of Inconel 718 material with a hardness of 45 \(\pm\) 2 HRC (Rockwell hardness scale). The chemical composition of the material used in the tests is presented in Table 1. The tests utilized a C6-PCLNL-45065-12 HP tool holder equipped with nozzles with an internal diameter of 0.8 mm, allowing for precise coolant delivery to the cutting zone. The cutting inserts used were CNMG 120408-SM with a corner radius of 0.8 mm made from two types of tool materials. The sintered carbide inserts had a wear-resistant coating of S205 (TiCN/Al\({}_{2}\)O\({}_{3}\)/TiN) applied using the CVD (chemical vapor deposition) method. The ceramic inserts 6160 were made of uncoated SiAlON. The tests were performed with a constant cutting depth of \(a_{p}\) = 0.2 mm. Feed rates \(f\) = 0.025, 0.04, 0.055, and 0.07 mm/rev were used. The cutting speeds for the sintered carbide inserts were 80 m/min and 200 m/min, while for the ceramic inserts, the cutting speeds were 200 m/min and 250 m/min. The turning tests were conducted on a M40 CNC machine using ECCool Global 10 coolant with a constant coolant pressure of 85 bar. ECCool Global 10 is an 8% concentrate based on mineral oil and 92% water.  
Surface topography and surface roughness were measured three times at three locations spaced 120 degrees apart around the circumference of the sample. The measurements were made using the Nanoscan 855 (Jenoptik, Jena, Germany). For data collection and presentation, the Hommel Map Premium 6.2.6409 software was used. The surface topography parameters were measured on an elementary surface with dimensions of 1.20 mm by 0.88 mm, on which 150 passes were made at a measurement speed of 0.5 mm/s, in accordance with ISO 25178 standards.  
The wear of the rake face and flank face was examined using a scanning electron microscope, Inspect S (FEI, Eindhoven, The Netherlands), equipped with an EDS Octane Elect (EDAX) X-ray microanalyzer. During the examination of carbide cutting tools, a backscattered electron detector (BSED) and a secondary electron detector (ETD--Everhart-Thornley Detector) were used at an accelerating voltage of 20 kV. In contrast, during the examination of ceramic cutting tools, a backscattered electron detector (BSED) and a secondary electron detector (LFD--large-field detector) were used, also at an accelerating voltage of 20 kV.  
The cutting edge radius of the tools used in the study was measured using a 3D Portable RL optical microscope (Bruker Alicona, Graz, Austria). Measurements were performed in 50 cross-sections, in a left-to-right direction.  
The wear tests were conducted using a UMT Bruker tribotester (Billerica, MA, USA), which is equipped with a three-axis motion system driven by high-resolution stepper motors. WC balls with a diameter of 9 mm were used as counter-samples.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Element** & **Ni** & **Cr** & **Fe** & **Nb** & **Mo** & **Ti** & **Al** & **Si** \\ \hline \% weight & 53.84 & 16.87 & 17.23 & 4.45 & 4.59 & 1.35 & 1.38 & 0.29 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical composition of Inconel 718 used in the tests.