# Analysis of the Chip Geometry in Dry Machining of Aeronautical Aluminum Alloys
## 4 Conclusions  
In this work, an analysis influence of the cutting parameters on chip morphology and geometry, during the dry machining of UNS A97075 (Al-Zn) and UNS A92024 (Al-Cu) alloys, has been carried out. Different geometric parameters of the chip have been measured, and their evolution with the feed and the axial machining length has been analysed.  
For both alloys, a continuous chip was obtained in the range of lower feed, with a tendency to form chip nests, whereas a segmented and shorter chip was obtained in the range of higher feed.  
Among the different chip geometric parameters analysed, the height of peaks (\(h_{c}\)), height of valleys (\(h_{v}\)), cross-section area (\(S\)), and thickness (\(t\)) have shown a trend to increase with feed. This fact was less noticeable for the UNS A97075 alloy due to its higher plasticity and greater capacity to withstand deformations before breaking. On the other hand, the shear angle (\(\varphi\)) and chip width (\(b\)) have shown a trend to remain almost constant with feed, for both alloys tested.  
Regarding the shrinkage factor (\(\zeta\)), its values were calculated by several methods. On the one hand, its values were calculated by using the shear angle (\(\varphi\)) experimental values and the tool geometry parameters (considering constant the parameters of the tool setup). On the other hand, they were calculated through the cross-section area (\(S\)) experimental values.  
The experimental results have revealed that the evaluation of \(\zeta\) by the first method is not suitable, due to alterations of the tool geometry during machining, which are caused by secondary adhesion wear. The results obtained by the second method have shown that \(\zeta\) increases with feed. In addition,  
\begin{table}
\begin{tabular}{c c c c|c c c} \hline \hline  & \multicolumn{3}{c|}{**UNS A92024**} & \multicolumn{3}{c}{**UNS A97075**} \\ \hline  & K & x & R\({}^{2}\) & K & x & R\({}^{2}\) \\ \(h_{c}\) & 1.20 & 0.84 & 0.99 & 1.09 & 0.76 & 0.97 \\ \(h_{v}\) & 0.92 & 0.88 & 0.98 & 0.56 & 0.60 & 0.98 \\ \(\mathbf{S}\) & 1.61 & 0.98 & 0.94 & 1.22 & 0.84 & 0.95 \\ \(\mathbf{t}\) & 1.14 & 0.96 & 0.91 & 1.13 & 0.90 & 0.90 \\ \hline \hline \end{tabular}
\end{table}
Table 5: Values of the coefficients obtained in the potential relationship from Equation (9).  
the lowest values of feed resulted in a lower value of \(\zeta\), so higher deformation grade was obtained. Once the shear limit has been reached (higher feed), this grade of deformation becomes lower. This fact was less apparent for the UNS A92024 alloy, due to reasons which are similar to those exposed above.  
No significant changes were observed in the parameters analysed as a function of axial machining length (\(L\)). Finally, different relationships have been obtained, which allow the prediction of the evolution of some of the geometric parameters of the chip, as a function of feed values. It should be pointed out that the results are valid within the range of tested cutting parameters.  
The authors want to thank the University of Malaga-Andalucia Tech, International Campus of Excellence, for its financial support on this paper.  
[PERSON] and [PERSON] conceived and designed the experiments; [PERSON] performed the experiments; [PERSON], [PERSON], [PERSON] and [PERSON] analyzed the data; [PERSON] wrote the paper; [PERSON], [PERSON] and [PERSON] revised the paper.  
The authors declare no conflict of interest.