With excellent properties, high-temperature superalloys have become the main application materials for aircraft engines, gas turbines, and many other devices. However, superalloys are typically difficult to machine, especially for the thread cutting. In this article, an ultrasonic vibration–assisted turning system is proposed for thread cutting operations in superalloys. A theoretical analysis of ultrasonic vibration–assisted thread cutting is carried out. An ultrasonic vibration–assisted system was integrated into a standard lathe to demonstrate thread turning in Inconel 718 superalloy. The influence of ultrasonic vibration–assisted machining on workpiece surface quality, chip shape, and tool wear was analyzed. The relationship between machining parameters and ultrasonic vibration–assisted processing performance was also explored. By analyzing the motion relationship between tool path and workpiece surface, the reasons for improved workpiece surface quality by ultrasonic vibration–assisted machining were explained.

Inconel 718 is a kind of nickel-based alloys that are widely used in the aerospace and nuclear industry owing to their high temperature mechanical properties. Cutting of Inconel 718 in conventional cutting (CC) is a big challenge in modern industry. Few researches have been studied on cutting of Inconel 718 using single point diamond tool applying the UEVC method. This paper shows an experimental study on UEVC of Inconel 718 by using polycrystalline diamond (PCD) coated tools. Firstly, cutting tests have been carried out to study the effect of machining parameters in the UEVC in terms of surface finish and flank wear during machining of Inconel 718. The tests have clearly shown that the PCD coated tools in cutting of Inconel 718 by the UEVC have better performance at 0.1 mm depth of cut as compared to the lower 0.05 mm depth of cut and the higher 0.12 or 0.15 mm depth of cut. Secondly, like CC method, the cutting performance in UEVC increases with the decrease of the feed rate and cutting speed. The CC tests have also been carried out to compare performance of CC with UEVC method.