Enhancing CFRP Machining Quality Using Longitudinal‐Torsional Ultrasonic Vibration‐Assisted Drilling

ABSTRACT Longitudinal‐torsional ultrasonic assisted drilling (LTUAD) is proposed for high‐quality machining of CFRP. Through theoretical and experimental analysis, the study establishes the cutting path equation and clarifies the mechanistic differences between LTUAD and conventional drilling (CD). The experimental results demonstrate that LTUAD significantly improves hole surface quality compared to CD. This improvement stems from the unique characteristics of LTUAD, including intermittent cutting, variable speed cutting, and variable angle cutting. Furthermore, the study reveals that hole surface roughness decreases with increasing ultrasonic amplitude, while it increases with higher spindle speed and feed rate. Optimal machining parameters for minimizing hole surface roughness were identified as follows: ultrasonic amplitude A = 8 μm, spindle speed n = 300 rpm, and feed rate f z = 0.005 mm/r.