Drilling performance of uncoated brad spur tools for high-strength carbon fiber-reinforced polymer laminates

High-strength carbon fiber-reinforced polymers have been a promising alternative to conventional fibrous composites because of their extremely high properties. Mechanical drilling is a necessary operation to create boreholes for riveting and bolting different composite structures into assemblies. However, the high-strength carbon fiber-reinforced polymers pose much more serious machining issues than the conventional ones. The present work aims to investigate the drilling performance of one type of uncoated carbide brad spur tools when applied in machining of high-strength carbon fiber-reinforced polymer laminates. The wear mechanisms of uncoated carbide brad spur drills were figured out. Additionally, the tool wear influences on the thrust force, hole dimensional accuracy, and drilling-induced delamination were quantified. The acquired results indicate that the tool wear has a significant impact on the drilling process and the quality of machined hole wall surfaces. The dominant wear mode is proved to be abrasion wear. Moreover, the uncoated brad spur drills appear to exhibit high resistance to the abrasion wear in the drilling of high-strength carbon fiber-reinforced polymer laminates.