## 1 State of the Art
Figure 5: The mathematical methods used to optimize the aluminum alloy cutting processes 2005–2019 period. Finally, the mathematical methods used to optimize the aluminum alloy cutting processes were analyzed, and the results show that the most studied methods are ANOVA with 35%, RSM with 26% and Taguchi with 24%. We consider Figures 1-5 important because these graphs are created based on a serious topical documentary. In this scientific paper, we use the Taguchi, the central composite design and ANOVA methods to obtain the optimal conditions for end-milling process of 7136 aluminum alloy used in the aerospace field. The aim is to obtain the contribution percentage of each parameter in order to confirm the optimal conditions obtained by using the Taguchi and the central composite design methods. Table 1 gives a brief presentation of the research papers in which this 7136 aluminum alloy was also studied. This research presents novelty elements in this field due to the experimental programs behind this applied research being permanently improved. Moreover, we consider that the approached subject is very topical, still being associated with the material sampling processes in various industries such as the aerospace industry. We consider that the study we propose represents a topical reference in our field of competence and is argued by topical experimental results that take into account a current stage \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Machining Process** & **Aluminum Alloy** & **Process Parameters** & **Objectives** & **Optimization/Prediction Technique** & **Ref.** \\ \hline End-Milling & 7136 & cutting speed, cutting depth & Comparison between the evolution of the machined surfaces quality according to process parameters & Practical experiment & [15] \\ End-Milling & 7136 & cutting speed, feed per tooth, cutting depth & Comparison of the surface quality evolutions in different situations related to the cutting regimes resulting from the combination of the process parameters & Practical experiment & [16] \\ End-Milling & 7136 & cutting speed, feed per tooth, cutting depth & Optimization of the surface roughness & Taguchi, full factorial design & [18] \\ Milling & 7136 & cutting speed, feed per tooth, cutting depth & Determination of the cutting parameters influence, on the surface quality & Taguchi & [19] \\ Milling & 7136 & cutting speed, feed per tooth, cutting depth & Determination of the optimum values of machining parameter and their interactions to obtain the better cutting process performance and to reduce the surface roughness sensitivity to uncontrollable factors & Regression analysis, ANOVA & [20] \\ End-Milling & 7136 & cutting speed, feed per tooth, cutting depth & To reduce manufacturing costs and processing time. To identify the quantitative relationships between cutting parameters and the surface roughness. & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Identified research on Al7136 machining. of knowledge in the field that was the basis of the proposed research. Considering the purpose of this article, which is to determine the surface quality equation produced by Al7136 end-milling, based on the above comparisons, the full test method will be presented.