Performance improvement of high-speed EDM and ECM combined process by using a helical tube electrode with matched internal and external flushing

Abstract

Micro-hole fabrication at a high speed and accuracy of machining while maintaining high surface quality is challenging. A core difficulty is the removal of the products of machining from extremely narrow gaps. To solve this problem, this study proposes an approach that combines high-speed electrical discharge machining (EDM) with electrochemical machining (ECM) by using a helical tube electrode with matched internal and external flushing. During high-speed electrical discharge drilling, matching the internal flushing with the clockwise rotation of the helical electrode can help remove debris from the bottom of the blind hole. During ECM, matching the external flushing with the anticlockwise rotation of the helical electrode can improve the flow of electrolyte in the gap. First, the flow field was simulated to show that matching the internal and external flushing of the helical electrode can enhance the flow of the medium and reduce particle concentration in extremely narrow gaps. Second, a series of experiments were conducted to verify that the taper of the hole and the surface quality of its wall can be improved by using the helical tube electrode. Finally, an experiment was carried out to optimize the machining parameters, and yielded a minimum taper of 0.008 at a speed of rotation of 460 rpm, and pressures of internal and external flushing of 9 MPa and 4 MPa, respectively.

Research of electrical discharge and electrochemical combined machining technology

“…In order to improve the above problems, some scholars hope to use the combination of EDM-ECM to improve the processing quality of small holes. Ji lei et aldesigned a spiral tube electrode and matched it with the internal and external flushing fluid [9] . When the rotation speed was 460 rpm, the internal and external flushing pressures were 9 MPa and 4 MPa, respectively, the minimum taper was 0.008.…”

Tooling aspects of micro electrochemical machining (ECM) technology: Design, functionality, and fabrication routes

“…Apart from that, a combination of spiral and tubular structures for a micro-tool has also been presented. Matching external flushing with counterclockwise rotation of the micro-tool improves the electrolyte flow within the gap and reduces the precipitate concentration (Ji et al, 2021;Zhang et al, 2019b;Zhang et al, 2019c). It has been proven that a trapezoidal spiral structure was beneficial in reducing the accumulation of the by-products and effectively removing the precipitates in Fig.…”

On Performance Enhancement of the STED Process Using Modified Tool Electrode

“…15 Ji et al employed helical tube electrodes matched with internal and external flushing along with tool rotation to enhance electrolyte flow and flushing of anodic byproducts from small gaps. 16 The present work attempted STED process performance enhancement through tool modification. While using standard tubular micro-tools, the tool feeding is limited due to short-circuiting.…”