Enhancing dimensional accuracy of the produced holes in CFRP by ultrasonic vibration assistance

Carbon fiber reinforced composites have many industrial applications due to their suitable mechanical and physical properties. Drilling is one of the common methods for creating connections between fiber-reinforced structures. Rotary ultrasonic drilling process is one of the new methods in machining fiber-reinforced composites, which has been highly regarded in recent years. Exact dimensional tolerance is one of the important issues in machining of carbon fiber reinforced composites. Therefore, in recent years, new tools such as cored diamond tools are used in drilling fiber-reinforced composites, considering force reduction and simultaneous drilling and grinding inside the hole. In this research, the dimensional accuracy in the drilling process using ultrasonic waves in carbon fibers reinforced composites has been investigated. The results indicate the effective axial force reduction in vibration drilling compared to traditional drilling. Besides, the results show that the cylindrical and roundness tolerance have been improved significantly while using ultrasonic vibrations. According to the examinations, it was observed that the tool rotational speed increasing and feed rate decreasing improve quality of the hole.