Influence of ultrasonic vibrations during drilling of carbon-fiber-reinforced polyetherimide composites

Carbon-fiber-reinforced polyetherimide (CFRP) is an advanced composite material that has a high strength-to-weight ratio, better fatigue, high mechanical strength, low friction coefficient and low weight. Drilling of composite is difficult due to the anisotropic and inhomogeneous structure of fiber and matrix that affects micro and macro geometrical damages. Conventional drilling of CFRP composite causes high temperature, cutting force, torque, fiber pull-out, damaged surface topology, microcracks and delamination. The present study leverages rotary ultrasonic-assisted drilling of CFRP composites and comparison with rotary drilling and normal drilling. The influence of different drilling parameters was investigated on cutting force, temperature, torque, surface roughness, material removal rate and microcracks produced at the drilled edge surface. It was observed that a rotational speed of 2500 rpm, 10 mm/min of feedrate, 420 µm of diamond grit sizes and ultrasonic power of 100 % for minimizing the cutting force, surface roughness, and torque. The rotary ultrasonic-assisted drilling of CFPR composite produces a precise cut with smooth surface morphology as compared to rotary drilling and normal drilling of composites. The application of rotary ultrasonic-assisted drilling using diamond-impregnated hollow tools can be leveraged for various industrial applications to avoid microcracks and fiber delamination.