Effect of drill flute direction on delamination at the exit in drilling Carbon Fiber Reinforced Plastic

Drilling holes on Carbon Fiber Reinforced Plastic components is inevitable for mechanical assembly in the aerospace field. Delamination at the exit frequently occurs and substantially reduces the service life of components. Drill flute direction is one of the main factors affecting delamination at the exit. The article aims to study the effect of drill flute direction on delamination and further to guide the suitable choice of drill flute direction. Comparative experiments are performed in drilling Carbon Fiber Reinforced Plastic for the drills with different drill flute directions, when a small cutting edge radius is involved. Based on the experimental results, the effects of drill flute direction on the thrust force, force state of the uncut fibers at the exit, and delamination propagation at the exit are obtained. Meanwhile, the phenomenon that delamination at the exit varies with the drill flute direction significantly is explained from aspects of thrust force and force state of the uncut fibers at the exit. The drill with left hand helix owns the most serious delamination at the exit among the tested drills because of its high thrust force and serious tearing function for the uncut fibers at the exit. POLYM. COMPOS., 40:E1434–E1440, 2019. © 2018 Society of Plastics Engineers