Experimental research on ultrasonic vibration countersinking process of CFRP composite laminates

Hole machining is a common operation during manufacturing of CFRP products. However, delamination, matrix chipping, and fiber pull-out easily take place in the machining of CFRP materials. Compared to straight through holes, tapered countersink holes are more difficult to be machined. In this paper, an ultrasonic vibration device was developed. The vibration performance of it was tested, and hole drilling experiments with the developed device are implemented, and the quality of holes is analyzed. The developed device produces 24.84 KHz vibrations on drill bit, and the vibration amplitudes at the drill edge and step edge are 2.62 um and 1.34 um, respectively. With the ultrasonic vibration drilling method, the average thrust drilling forces are reduced 8-21.5%, and the hole quality is improved significantly. This study provides a potential device and technique for countersinking of CFRP composite laminates.