Hybrid tool electrodes for electrical discharge machining: fused deposition modeling combined with electroless copper plating and copper electroplating

Abstract

The fabrication of tool electrodes with complex geometries remains a major technological challenge in electrical discharge machining (EDM). This critical review analyzes a hybrid strategy that combines additive manufacturing of a polymer core with subsequent electroless and electrolytic copper deposition to obtain electrically conductive tool electrodes. The principal 3D printing technologies—FDM/FFF, SLA/DLP, SLS, and PolyJet—are compared for polymer core fabrication. By the considered criteria, FDM/FFF and SLA/DLP show the greatest practical potential for polymer cores for subsequent metallization. FDM/FFF offers equipment/material availability and process flexibility; SLA/DLP provides lower surface roughness and higher dimensional accuracy. FDM parameters – layer thickness, nozzle temperature, infill density, and build orientation – are examined for effects on geometric accuracy, surface roughness, and thus metal coating adhesion and uniformity. Primary metallization methods (electroless deposition, physical vapor deposition, conductive pastes) and subsequent copper electroplating are analyzed. A synthesis of experimental data shows that in most studies that included a comparison with a solid copper tool electrode, electrodes with a printed polymer core (mainly ABS) and a copper coating provided comparable material removal rate, wear, and machined surface roughness under finishing and semi-finishing conditions; at the same time, in several studies the hybrid electrodes were inferior to solid copper in material removal rate or wore 1.1–2.8 times faster, and data on the service life of the copper shell are lacking. Optimizing FDM parameters and selecting a metallization method should be treated as interdependent stages of an integrated process chain determining hybrid tool electrode performance.