## 2 Materials and Equipment  
The choice of the sample corresponded to the most common machined surfaces experienced in the production process. For the experimental process, the shape of the pocket was used, as shown in Figure 1. The chosen component dimensions are presented in Figure 1a, and a 3D model of the part is shown in Figure 1b. A total of four test samples were produced, where four different milling strategies were used and evaluated. The material of the sample parts was aluminum alloy (AlCu4 Mg), and its dimensions were 60 \(\times\) 60 \(\times\) 30 mm. The mechanical properties of the selected material AlCu4 Mg alloy are shown in Table 1.  
For a CAD model design, the CAD system Solidworks was used, and for the generation of the tool path, the CAM system SolidCAM was used. For the milling process, a 3-axis milling machine EMCO Mill 155 (EMCO MAIER Ges.m.b.H., Hallein/AUSTRIA), was used. The maximum rotation speed used in the experimental process when test samples were produced was 5000 r/min. All test samples were produced by 3 operations: roughing, semi-finish, and finish operation, while only the finish strategies were varied. Constant Z, Circular pocket, Constant stepover pocket auto border and spiral were evaluated and compared. Table 2 shows the cutting tools used in the production process with selected cutting parameters. All cutting parameters were recommended in accordance with tool manufacturers. End Mill D18 with two interchangeable cutter plates marked APXT11T3 PDR-MA was used for the roughing operation. A ball end mill D8 was used for the semi-finish operation, and a ball end mill D6 was used for the finish operation. Tools for the semi-finish and finish operation were clamped in a BT-40 clamping system by a mechanical collet chuck, and their overhang length was 50 mm. Machining operations were conducted in the following steps:  
* Roughing operation--end mill tool D 18 mm, depth of cut a\({}_{\text{p}}\) = 1 mm, side step a\({}_{\text{e}}\) = 2 mm, toolpath tolerance T = 0.1 mm, surface allowance P = 0.5 mm; \begin{table}
\begin{tabular}{c c c} \hline
**Tensile Strength [MPa]** & **Yield Strength [MPa]** & **Hardness [HB]** \\ \hline
101.89 & 86.69 & 90.20 \\ \hline \end{tabular}
\end{table} 
Table 1: The basic mechanical properties of the selected AlCu4 Mg alloy. Figure 1: Test sample (a) dimensions of the test sample (b) 3D model. * Semi-finish operation--ball end mill D 8 mm, cutting material HSS Co8, depth of cut a\({}_{\text{p}}\) was defined in accordance with the scallop height setting in the CAM system, where the value was 0.1 mm, surface allowance P = 0.2 mm;
* Finishing operation--ball end mill D 6 mm, cutting material HSS Co8, a\({}_{\text{p}}\) = 0.4 mm, side step a\({}_{\text{e}}\) = 0.25 mm, toolpath tolerance T = 0.01 mm, scallop height SH = 0.01 mm. A more detailed characterization of the finishing strategies used in the experiment is described below. * Constant Z--This strategy produces high-quality finishes, especially on steep surfaces, and minimizes movements in all three axes that slow older machines and control systems. This strategy allows the function of machining flat areas. Work areas will be automatically created and can be machined using contour pocket machining. The schematic diagram illustrated Constant Z strategy is shown in Figure 2;
* Circular pocket--This strategy uses the selected workspace to create a linear 2D pocket field on the plane above the model. The linear field is then projected into the 3D model [41; 42]. The schematic diagram illustrating the circular pocket strategy is shown in Figure 3;
* Constant stepover--3D projection machining strategies generate a 2D toolpath with a constant pitch in a plane parallel to the XY plane of the current zero point. This 2D toolpath is then projected onto the 3D model to create a 3D toolpath. This method offers good results when machining prismatic parts but has significant disadvantages when machining curved surfaces because it does not incorporate the curvature of the surface.