An experimental evaluation of cryogenic machining in the drilling of carbon fiber reinforced plastics for aerospace

Abstract

The present research aims at studying both dry machining and alternative solutions to wet machining in the drilling of carbon fiber-reinforced polymers (CFRPs). CFRPs are key materials in aerospace and their drilling is critical and challenging. Specifically, cryogenic fluids such as CO₂ and N₂ were investigated. Drilling tests were performed using three different CFRP laminates. These CFRP laminates are composed of various unidirectional plies of different orientations. Thus, the configurations to analyze were: 0/90/45, 30/60 and 0/90. As output variables, surface roughness, diameter deviation, delamination and thrust forces were analyzed. In general, the internal application of CO₂ and dry machining were the best- and worst-performing techniques for surface roughness, respectively. Regarding the dimensional quality, both CO₂ and dry machining offered the best results. In the case of LN₂ or LN₂ + CO₂, the results showed that the CFRP configuration is critical for the obtained results. However, it was identified that cryogenics can improve the results of the dry machining process under certain conditions in terms of delamination. Finally, in general, CO₂ provided the worst results when attending to the thrust forces.