Multi-axis CNC milling of complex surfaces in 7075 aluminium for aerospace applications

Abstract Multi-axis CNC milling is widely used in the manufacturing of components with complex surfaces and is particularly valued in demanding sectors such as the aerospace industry. In this context, aluminium alloys play a prominent role due to their strength-to-weight ratio and high machinability. This work aims to assess how milling strategies and cutting tools affect surface quality and process efficiency when machining complex surfaces in AW-7075 aluminium alloy, by testing different finishing strategies, tool tip radius ( $$\:{r}_{tip}$$ ), and radial depth of cut ( $$\:{a}_{e}$$ ). Findings show that the machining strategy is the most influential factor on both surface quality and cutting time. A reduction in $$\:{a}_{e}$$ contributed to a slight improvement in surface quality, while an increase in $$\:{r}_{tip}$$ proved beneficial only for certain strategies. Regarding process efficiency, increasing $$\:{a}_{e}$$ and $$\:{r}_{tip}$$ significantly reduces machining time. Given aerospace industry demands, the Flow strategy with a 4 mm $$\:{r}_{tip}\:$$ and 0.05 mm $$\:{a}_{e}$$ proved to be the most balanced solution, achieving low cutting times and Ra within specifications (0.25–0.40 μm). It was concluded that the appropriate combination of cutting parameters, machining strategies, and tool geometry, enables compliance with strict quality standards while enhancing overall process efficiency.