Cooling Process of Reverse Air Suctioning for Damage Suppression in Drilling CFRP Composites

Carbon fiber reinforced plastic (CFRP) composites are the first choice for high-end equipment in fields of aviation and aerospace pursuing weight reduction. However, producing high quality holes in drilling of CFRP remains a long-standing challenge mainly due to its weak interlaminate bonding and sensitivity to temperature. This article proposed a novel cooling process for drilling of CFRP, deploying reverse air suctioning, to reduce drill-exit damages. The concept of the proposed cooling process is to change the coolant flow direction, with the benefits of reducing the force of the coolant acting on the drill exit and increasing the constraint of the drill-exit material. Comparative experiments are conducted under dry and reverse air suctioning conditions. Results show that the proposed cooling process can significantly reduce the drilling temperature, below Tg. Despite the cooling process has led to increased thrust force, the drill damages have been reduced as compared with the dry drilling, and the potential damage suppression mechanisms have been discussed.