Experimental investigation on micro-drilling machinability of additive manufactured and traditional forged Ti6Al4V titanium alloys

Abstract

The rise of additive manufacturing (AM) technology has propelled the in-depth application of titanium alloy materials in industrial fields such as aerospace, military, and medical. Post-processing, including micro-drilling, is a crucial step to ensure the successful utilization of additive manufactured (AMed) components. In this study, micro-drilling machinability of Ti6Al4V titanium alloys that fabricated by selective laser melting (SLM) process before and after heat-treatment was studied. The forged titanium alloy was selected as a comparison. The findings indicate that the thrust force and micro-hole wall surface quality of titanium alloy materials are more sensitive to the changes in feed rate. The additive manufactured titanium alloy before heat-treatment exhibits the maximum thrust force and micro-hole wall surface roughness. Material strength exerts a more pronounced effect on the thrust force during drilling compared to material hardness, while micro-defects are the factors that contribute to the deterioration in surface quality. Additionally, the exit burr of the forged titanium alloy shows the largest size, which is 34.28 % and 8.73 % greater than that of the AMed titanium alloys before and after heat-treatment. Smaller feed rate and larger spindle speed are helpful to reduce the exit burr size.