## 1 Introduction
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Machining** & **Tool Materials/Coatings** & **Aluminium** & **Conclusions** & **Ref** \\ \hline One shot-drilling process & HSS uncoated drills Coatings: TiAlN/TiN (multilayer) & & The results showed that the coatings did not show any significant impact on the temperature of the workpiece and the surface texture of the holes. & [7] \\  & TiAlN & & However, drills with coatings of TiAlN/TiN and TiAlN showed better dimensional accuracy of the hole. & \\ \hline One shot-drilling process & Uncoated carbide Coatings: TiN + Ag & Al2024-T351 & It was reported that in terms of hole quality and tool life in dry drilling of Al2024, the coated drills did not perform well, expect a diamond and Hardlube coated drills with results closed to that obtained in uncoated charloffs. & [8] \\  & TiAlN + WC/C Diamond & & \\ \hline One shot-drilling process & Uncoated HSS Coatings: Cobalt & Al2024 & The study recommended that in comparison to uncoated HSS drills, the longer tool life was obtained when the HSS-Co drills were used. & [9] \\ \hline \multirow{7}{*}{Turning} & Uncoated carbide Coatings: TiC & It was concluded that coatings were not successful in dry machining of pure aluminium and Al–12\% Si alloys because of the formation of built-up edge on the tools and subsequent increased in cutting forces and surface roughness of the materials. & \\ \cline{2-4}  & TiN Al2023 & Pure aluminium and Al2023 Si Al2024 & It was concluded that coatings were not successful in dry machining of pure aluminium and Al–12\% Si alloys because of the formation of built-up edge on the tools and subsequent increased in cutting forces and surface roughness of the materials. & \\ \cline{1-1} \cline{2-4}  & Uncoated HSS Coatings: TiAlN & Al2024 & The use of TiAlN and TiN coated HSS drills were not recommended at low cutting parameters. The only coated drill suggested in their study was the HSS-Co 5\% that delivered an outstanding performance in all cutting parameters. & \\ \cline{1-1} \cline{2-4}  & TiN Al2024 & Al2024 & The use of TiAlN and TiN coated HSS drills were not recommended at low cutting parameters. & \\ \cline{1-1} \cline{2-4}  & TiN Al2024 & Al2024 & The use of TiAlN and TiN coated HSS drills were not recommended at low cutting parameters. & \\ \cline{1-1} \cline{2-4}  & TiN Al2024 & Al2024 & The use of TiAlN and TiN coated HSS drills were not recommended at low cutting parameters. & \\ \cline{1-1} \cline{2-4}  & TiN Al2024 & Al2024 & The use of TiAlN and TiN coated HSS drills were not recommended at low cutting parameters. & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Previous studies on the machining of aluminium alloys using coated drill bits. However, there is a need to research further to evaluate the performance of multi-spindle drilling for better hole quality when several coated tools are used simultaneously to create multiple holes in one go. Therefore, this study includes the investigation of coatings of TiN and TiCN on carbide tools in Al2024 using the multi-hole simultaneous drilling approach. In addition, an artificial neural network (ANN) is employed for the prediction of \(R_{a}\) using the multi-layer perceptron (MLP) technique. An ANN is an artificial intelligent technique used for modelling and predicting the response of complex production systems [20]. Additionally, manufacturing industries such as aerospace, automobile etc. have increased demands for products with high surface finishes where the \(R_{a}\) is considered as a high surface quality indicator [21]. For these reasons, modelling of \(R_{a}\) is of significant interest for research [20].