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Closed curved and twisted channels are widely used in key parts of aerospace vehicles; however, they are difficult to process. Electrical discharge machining is a common method for machining curved and twisted channels of integral components. The electrode trajectory determines the machining quality and efficiency. We adopted a target evaluation function to distinguish between the local and global optima for an integral component with a long and narrow two-dimensional curved and twisted channel. In addition, we combined heuristic search and rapidly exploring random tree search to design and optimize the machining trajectory of the electrode. Finally, we conducted a comparative experiment between a preliminary design scheme and the proposed optimization method. The test results show that the machining efficiency and accuracy of the proposed method are higher than those of the preliminary design scheme. Furthermore, the machining trajectory generated by the proposed method satisfies the comprehensive requirements to produce two-dimensional curved and twisted channels. [ABSTRACT FROM AUTHOR]

This study fabricates a roughing electrode of electrical discharge machining (EDM) using a rapid prototyping (RP) system and investment casting technology, which reduces the overall time that is required for fabrication and the cost of the manufacturing process for a selected electrode. Pro/E (3D CAD) software is used to design the electrode prototype, which has a complex appearance, and to transform the CAD model into stereolithography (STL) format. An RP machine (Zcorp 402 3DP) is used to construct a gypsum-based powder model. After a sealing process using the permeation of resin, the water resistance and strength of the gypsum-based material are increased. The manufacturing process then involves creating a wax model with a gypsum electrode that is strengthened by resin permeation by casting a vulcanized silicone molding. The brass electrode is fabricated using investment casting technology. The results of an EDM test show that the brass electrodes with RP that are manufactured perform well and the total time that is required to machine the EDM electrode using RP is 15.8% less than the time that is required for a CNC machining process. [ABSTRACT FROM AUTHOR]

To improve the efficiency of conventional electrical discharge machining (EDM) milling, this study proposes a highly efficient machining method that employs continuous oxygen feeding and fast-moving electrode. High-efficiency machining is achieved by the method of feeding with small thickness, allowing the electrode suspended above the workpiece to reduce short circuit and using a high discharge probability to ignite the workpiece in order to realizing high efficiency machining with great chemical energy released from metal combustion. Comparative tests for conventional EDM milling, EDM ablation milling, and ablation milling by fast-moving electrode were performed in the milling process. In this study, we analyzed the mechanism, machining efficiency, electrode relative wear ratio, and machining quality. The machining efficiency of EDM ablation milling was 6.8 times higher than that of conventional EDM milling, and the relative tool wear ratio was 20% of conventional EDM milling; the machining efficiency of ablation milling by fast-moving electrode can reach 11.2 times higher than that of conventional EDM milling, and the electrode relative wear ratio decreased by 86%. [ABSTRACT FROM AUTHOR]

Investigations were conducted on the machining of AISI D2 tool steel via Conventional electrical discharge machining (CEDM) and Cryogenic cooled electrode in electrical discharge machining (CCEDM). Machining parameters, including discharge current, pulse on time, and gap voltage, were varied to investigate their effects on machining performance such as on Electrode wear ratio (EWR), surface roughness (Ra), microstructure, surface morphology, and elemental composition. Experimental results showed that EWR was reduced by 20% in CCEDM compared with in CEDM. Moreover, the Ra in CCEDM decreased by approximately 19% compared with that in CEDM. The results also indicated that the surface morphology of the workpiece machined via CCEDM was better than that of the workpiece machined via CEDM. Lastly, the damaged layer and microcracks were less in the workpiece machined via CCEDM than those in the workpiece machined via CEDM. [ABSTRACT FROM AUTHOR]

Die-sinking electrical discharge machining is an unconventional technology that allows to machine all at least minimally electrically conductive materials regardless of their physical and mechanical properties. Despite the fact that it is not a conventional technology, the tool gets also worn out, which is a tool electrode. The wear of the electrode does not only mean its loss but also the degradation of the shapes that are transferred to the resulting workpiece. For this reason, a design of experiments was conducted with 6 input factors, 2 were categorical: the electrode material (copper, graphite) and workpiece material (steel 1.2363 and steel 1.2343ESR) and 4 were numerical: Open-voltage, Pulse current, Pulse on-time, and Pulse off-time. In the framework of this design of experiments, the wear of the used graphite and copper electrodes at their corners and edges was evaluated, which was made possible by the use of electron microscopy and the use of approximation circles. Furthermore, the eroding speed, the topography of the machined samples, and the morphology of the surfaces of the used electrodes were investigated. It has been recognized that the use of a graphite electrode will allow for more accurate workpiece shapes and less wear. [ABSTRACT FROM AUTHOR]