Drilling of CFRP-Ti6Al4V stacks using CO₂-cryogenic cooling

In the work here presented, liquefied CO₂ is used as cutting fluid for drilling CFRP-Ti6Al4V stacks as alternative to dry-drilling. Several tests were performed using dry-drilling technique, to compare this with the performance of CO₂ cryogenic cooling. This work shows the feasibility of the proposed alternative, not only regarding technical issues but also environmental concerns. Results show that when CO₂ is used in drilling, hole diameter values diverge below 0.5 % from nominal values, tool tip temperature is drastically reduced, and surface integrity of CFRP layers are preserved. Drilling tool edges damage is reduced and so tool life extended. In short, dry-drilling process was notably improved by CO₂ assistance in comparison with dry drilling.