Process-window for dry drilling of woven CFRP laminates

Drilling of carbon fiber reinforced polymer (CFRP) laminates often generates defects that compromise structural integrity and service life. This study investigates drilling-induced damage in bidirectional woven CFRP laminates by examining the effects of machining parameters, laminate thickness, and thermal evolution. Results show that damage is mainly concentrated at the hole exit. Entrance delamination is primarily governed by feed rate, whereas exit delamination is more sensitive to cutting speed. Thinner laminates exhibit increased push-out delamination due to reduced support during tool breakthrough. Temperature analysis indicates that exit damage intensifies when the peak drilling temperature exceeds the resin glass transition temperature, promoting matrix softening and fiber–matrix debonding. ANOVA reveals that feed rate controls thrust force, torque, and entrance delamination, while cutting speed significantly affects exit delamination and maximum temperature. Increasing feed rate reduced temperature by 24%, whereas higher cutting speed increased exit delamination by 47%. These findings provide practical guidelines for minimizing drilling-induced damage in CFRP structures.