Influences of gap pressure on machining performance in radial ultrasonic rolling electrochemical micromachining

Microdimples as a typical surface texture has been widely used for improving the properties in tribology and heat transfer fields. Ultrasonically assisted electrochemical micromachining (USEMM) is a popular method for generating microdimples as it can reduce the overcutting and enhance electrolyte renewal to improve the machining localization and promote the material removal. However, the fundamental understanding of the process and particularly the relationship between the machining performance and gap pressure is limited. In this paper, radial ultrasonicrolling electrochemical micromachining (RUREMM) is employed to generate microdimples on SS304 surface. Effects of gap pressure on the material removal rate, machining accuracy, and roughness are studied and discussed in detail. Results show that RUREMM can fabricate the microdimples and the existing ultrasonic vibration in the inter-electrode gap is more effective to enhance the machining performance. By using the selected parameters in RUREMM, the current density during machining has a 6.6% increase in RUREMM than in EMM. Moreover, the width of the microdimple is decreased by 14.6%, the depth of the microdimple is increased by 19.2%, the cross-sectional area of the machined dimple is expanded by 31.2%, the roughness of the bottom is decreased 23.9% and also, better surface quality for the side wall could be obtained.