Experimental comparison of conventional and ultrasonic-assisted high-speed drilling of glass fiber reinforced epoxy composites

Glass fiber reinforced epoxy composites are favored in several industries, including automotive and aerospace, owing to their superior strength-to-weight ratio. Drilling is a prevalent machining procedure employed to add fasteners for laminate assembly. Nonetheless, drilling these composites presents significant challenges due to the abrasive characteristics of the reinforcement, necessitating an examination of machining performance. During the drilling of composites, cutting temperature, thrust force, and delamination damage are primary concerns. In recent years, high-speed ultrasonic drilling, an innovative machining technique designed to address these challenges, has garnered significant interest. This investigation involved high-speed ultrasonic drilling and conventional drilling of glass fiber reinforced epoxy material. In the studies, optimal conditions were studied by evaluating thrust force, cutting temperature, and delamination damage by varying speeds, feed rates, and frequencies. The thrust force was 11 N in the traditional approach at 40,000 rpm, but it was recorded at 9 N with the ultrasonic method. Moreover, with ultrasonic drilling, cutting temperatures decreased by over 25% relative to traditional drilling, attributable to the harmonic motion that dissipates heat in the drilling zone. Analysis of the drilling region revealed a notable enhancement in damage, particularly in delamination, with the application of ultrasonic drilling. The experimental results indicate that ultrasonic machining enhances machining performance.