Abstract
Drilling is one of the most critical finishing operations in Carbon fiber reinforced polymer (CFRP) machining, yet the variation of axial drilling force and delamination factor with cutting speed remains unclear, hindering understanding of damage mechanisms and rational process-window design. From a thermo-mechanical coupling perspective, this study establishes a causal chain—spindle speed and feed per revolution → local temperature field → load response → damage and dimensional accuracy—and validates it through systematic drilling tests on quasi-isotropic laminates. Axial drilling force, torque, and temperature were measured synchronously, while hole-wall roughness, tear-out area, and delamination factor were quantified using confocal microscopy/ Scanning electron microscopy (SEM) and ultrasonic C-scan. Results show a segmented thrust–speed trend (rise → drop → plateau), where the transition corresponds to matrix softening as temperature exceeds Tg. Overall, temperature increases with speed but decreases with feed at low levels; exit delamination follows a temperature-dependent critical axial drilling force. Integrating these effects yields a robust process window—moderate speed with moderate feed—that balances low damage and dimensional stability. Complementary measures such as sharp coated drills, directed cooling, and minimum-quantity lubrication further enhance quality, providing a transferable basis for parameter optimization in precision CFRP drilling.