Research on ultrasonic-assisted drilling in micro-hole machining of the DD6 superalloy

The DD6 nickel-based superalloy exhibits remarkably high temperature properties; therefore, it is employed as a crucial structural material in the aviation industry. Nevertheless, this material is difficult to process. Ultrasonic-assisted drilling (UAD) combines the characteristics of vibration processing technology and conventional drilling technology, significantly improving the machinability of difficult-to-machine materials. Thus, UAD experiments were performed on micro-hole machining of DD6 superalloy in this study. The effects of amplitude, frequency, spindle speed, and feed rate on thrust force, machining quality, and drill bit wear were studied; thereafter, a comparison was drawn between these effects and those of conventional drilling (CD). The experimental results reveal that the thrust force decreases with an increase in spindle speed or a decrease in feed rate for both UAD and CD. UAD can significantly reduce the thrust force. With the same processing parameters, the greater the amplitude, the greater the reduction of the thrust force. The surface roughness of the hole wall produced by UAD is lower than that of CD. Compared with CD, UAD reduces the burr height, improves machining accuracy, and reduces drill bit wear.