A novel Cu-Gr composite electrode development for electric discharge machining of Inconel 718 alloy

Requirement of processes with high productivity leads to the development of new tools and machining technique. One such attempt was made to develop a Copper Composite (CC) tool reinforced with graphite particles through the stir casting route. The CC tool was utilized to machine the Inconel 718 alloy using Electric Discharge Machining (EDM) technique by varying input variables viz tool material, discharge current, pulse on time, pulse off time and gap distance. Brass, Copper, Copper-5% Graphite (CG5), Copper-10% Graphite (CG10), Copper-15% Graphite (CG15) are the various used tool material whereas Material Removal Rate (MRR), Tool Wear Ratio (TWR) and Surface Roughness (R-a) were recorded as responses. The results revealed that using the CG10 and CG15 tools causes arcing and open circuit under some parametric conditions. CG5 offers best MRR and least TWR owing to the bridging effect, high thermal conductivity and lesser density which was suitable for roughing operation whereas brass offers least R-a which was recommended for finishing operation. The surface topography was analyzed with the aid of Scanning Electron Microscope (SEM). Micro crack, pock marks, globules and remelted layers are some of the defects observed in surface morphology. The process parameters was optimized using VIKOR technique.

Automated summary

The requirement for processes with high productivity has driven the development of new tools and machining techniques, one of which is the development of a Copper Composite (CC) tool reinforced with graphite particles. By using different input variables and analyzing surface morphology, the best applications for different tool materials were identified based on Material Removal Rate (MRR), Tool Wear Ratio (TWR), and Surface Roughness (R-a).