Reversed-Air Cooling Technology for High-Quality Drilling of CFRP

Drilling is commonly adopted in the manufacturing process of large CFRP structural components for meeting assembly requirements. However, undesirable burrs occur frequently due to the weak restrictive conditions at hole-exit and the excessively high cutting temperature, decreasing the components’ assembly performance. This study aims to propose a novel damage suppression method which can simultaneously enhance the hole-exit’s support and decrease the cutting temperature in drilling of CFRP. For the first time, the idea of non-contact support is proposed and realized by exerting an appropriate cooling airflow from the direction opposite to the tool’s feed at the hole-exit, which makes a step forward existing CFRP drilling technology in the aspects of conveniently and also efficiently suppressing the burrs. For determining the appropriate pressure of reversed airflow, in this study a method combining theoretical model and experimental method is employed, and upon which the optimal value and specific influences on hole-exit’s qualities are obtained. From the results, it is clear that excessively strong airflow will aggravate fiber-matrix interface cracks in planes of CFRP, while airflow with not enough strength cannot reach the expected effects on the burrs’ suppression. In the situation in this study, the optimal pressure is about 0.0083 MPa. The proposing of the reversed-air cooling technology is beneficial to the development of high-quality and high-efficiency drilling technology of CFRP.