Drilling-induced damage suppression on CFRP/Ti-6Al-4V stacks using textured drills

Minimizing the drilling-induced damage on the walls and sub-surfaces of the drilled holes is a challenging but demanding task, especially on hard-to-machine materials such as CFRP/Ti-6Al-4 V stacks. In general, these stacks are highly preferred in aerospace structural applications. This paper analyzes the surface integrity of the drilled CFRP holes when they are stacked above the Ti-6Al-4 V alloy, by incorporating the laser-based marking of micro-textures on the flank and rake faces of the drill, which enables the micro-pool lubrication between the cutting-edges and work material. Comparative experimentations were conducted under MQL conditions. Considering the flank face micro-grooved drill, consistently lower thrust forces were observed across the entire range of cutting speeds and feeds, achieving reductions of up to 17 to 20%. Furthermore, the tool life study was performed, which reveals a substantial 26% enhancement in tool life with the flank face grooved drill, emphasizing its significant advantages for enhanced machining performance.