# The Influence of Automated Machining Strategy on Geometric Deviations of Machined Surfaces
## 2 Plan of Experiment
### Machine Device, Cutting Tools and Cutting Parameters  
The machining of aluminum parts was carried out on the 3-axis milling machine EMCO Concept Mill 155 (EMCO MAIER Ges.m.b.H., Hallein/AUSTRIA) with control system Heidenhain TNC 426 (JOHANNES HEIDENHAIN GmbH, Germany). CAM software  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Chemical Composition** & **Content [\%]** \\ \hline Cu & 4.30 \\ Mg & 0.79 \\ Fe & 0.26 \\ Si & 0.24 \\ Mn & 0.3 \\ Ti & 0.04 \\ Zn & 0.04 \\ Al & balance \\ \hline \hline \end{tabular}
\end{table}
Table 1: Chemical composition of AlCu4 Mg alloy [17].  
Figure 1: The dimensions and geometrical tolerances of test sample.  
today offers several possibilities of strategies for distributing the tool path in the domain of the designed part. Table 2 shows a list of cutting tools and cutting parameters for milling of the AlCu4 Mg alloy. The methodology for selecting cutting parameters was chosen based on the recommendations of the tool manufacturer and concerning the parameters of the CNC machine. The maximum RPM of the machine EMCO MILL 155 was 5000. The tool of \(\mathcal{O}\)18 mm in diameter was produced by Korloy (designation AMS 20185) with two interchangeable cutters plates marked APXT11T3 PDR-MA. The other tools were produced by ZPS-FN.  
The manufacturing process of the part was performed by the face milling, roughing and finishing strategies (Figure 2). For both produced test samples, the same roughing and finishing strategies were used. The coordinate system defined for the milling process is shown in Figure 1 (blue cross). The production of samples is described in the following steps:  
* Face milling of the top surface marked Plane C, in Figure 3, where the strategy zig-zag was used.
* Milling (roughing) a flat side surface marked Plane A, A-PER, where strategy contour with offset was used. After this operation, an allowance of 0.3 mm was left, which was removed by a tool with a smaller diameter.
* Milling (roughing) a two-sided surface marked Plane B1, B1-PER_long, Cyl1, B1_short, Plane B2, B2-PER_long, Cyl2, B2_short. After this operation, the allowance of 0.3 mm was left too and was removed by a tool with a smaller diameter.  
For production two different programs were used. The first was the CAM system Solidcam and the second was the control system Heidenhain TNC 426. The tool path of the tool for the milling of this part was programmed manually in the control system Heidenhain TNC 426. For the produced test samples, both programs used the same strategies and the same cutting parameters. The shape of parts was obtained in two stages: roughing and finishing. After each roughing operation, an allowance of 0.3 mm and a depth of cut for each operation of ap = 1.5 mm were implemented on the surface.  
We compared two different programs, where the strategies were programmed, and their effect on the quality of the surface of test samples was evaluated. Surface quality is influenced by several process parameters, such as tool diameter, cutting parameters, work piece material properties, clamping of the part and milling strategy. Among the most important factors is the milling strategy, which influences produced part accuracy.