**4. Conclusions**

The structured surfaces with various micro/nano characteristics may have different advanced functions in various fields. However, the machining of micro/nano structured surfaces is becoming a challenge for traditional cutting methods on the difficult-to-cut materials. This chapter focus on the EVC technique which is a promising way for structured surface machining. The advantages of EVC were described in detail. Meanwhile, the methods for realization of EVC were also introduced in detail. As is known, the flexure-based non-resonant type EVC vibrator has more flexibility and modulation ability compared with the resonant type EVC vibrator and it has been widely concentrated in recent years. Therefore, this chapter mainly reviews the recent developments and achievements on flexure-based EVC vibrators

actuated by piezoelectric actuators. According to the locus characteristics of cutting tool and its position and posture, the EVC was categorized into three different types. And this chapter reviews some typical examples according to the different types of EVC, including the mechanical structure, working principle of piezoelectric actuator, the static modeling, kinematic and dynamic modeling, structure optimization and testing. Although the flexure-based EVC vibrator developed rapidly, there are still some important problems that severely restricted the performance of EVC vibrator, which need to be further investigated in the future, such as the conflict between high working bandwidth and large working stroke, topological optimization of mechanical structures, fatigue life problems under long working hours, and design of highperformance controller.
