Study on machining characteristics of magnetic field assisted micro-EDM with ultrasonic vibration of workpiece

Abstract

Abstract Electro discharge machining (EDM) has become one of the most commonly used methods for deep micro hole drilling because of its advantages of no macro force and no limitation of material mechanical properties. However, the characteristics of small discharge energy and narrow discharge gap of deep micro hole drilling by EDM, which leads to the problems of removing erosion debris. The problem of unstable machining process and low efficiency of EDM hinders its application and development. In this paper, the technology of magnetic field assisted micro-EDM with ultrasonic vibration of workpiece is studied to realize high efficiency and quality machining of micro holes with large aspect ratio. The working fluid in the discharge gap will generate alternating pressure driven by the workpiece electrode under ultrasonic vibration, which will promote the discharge debris to be removed from the machining area. The working fluid in the discharge gap will generate alternating pressure driven by the workpiece electrode under ultrasonic vibration, which will promote the discharge debris to be removed from the machining area. Under the influence of electric field and magnetic field, the moving direction of charged particle deflects due to the joint action of Coulomb force and Lorentz force, which prolongs its moving path in the discharge gap. In the study of multi energy field composite machining performance, the most significant factors affecting the material removal rate in the process parameters are ultrasonic amplitude, magnetic induction intensity and peak current, among which the interaction between ultrasonic amplitude and peak current is the most significant. The results also show that carburization and metallization occur simultaneously on the EDM surface, and the hardness of the surface layer of titanium alloy EDM is greater than that of the substrate material. Ultrasonic vibration and magnetic field assisted micro-EDM can reduce the surface residual tensile stress and crack size.