Investigation on performance characteristics in drilling of Ti6Al4V alloy

Titanium alloys are attractive materials for aerospace, biomedical and chemical engineering due to their excellent combined performance of high specific strength and fracture resistant characteristics. Drilling titanium alloys is essential to the bolted/rivet connection in the assembly of aerospace parts. This paper outlines a comprehensive analysis of drilling characteristics and hole quality/integrity assessment following drilling titanium alloy Ti6Al4V without coolant under different machining parameters. The experimental results show that hole quality can be improved by proper selection of cutting parameters. This is substantiated by monitoring thrust force, hole diameter, circularity, chip formation, and surface finish. It was observed that the thrust force increased rapidly with respect to feed rate, which was increased by 2.5 times when the feed was increased from 0.05 to 0.13 mm/r as a constant cutting speed of 40 m/min. In addition, the circularity was found to be around 4 μm at low feed rate, when the feed was increased the circularity increased to 10 μm. The experimental results also indicated that the shape and the size of chips were strongly influenced by feed rate. Observation on the subsurface of drilled workpiece indicated a severe plastic deformation under different cutting conditions. This study demonstrates that using proper process parameters plays an important role in improving machining efficiency and guaranteeing quality in dry drilling titanium alloy.

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