Selected Aspects of Surface Integrity of Inconel 625 Alloy after Dry-EDM in Carbon Dioxide

Abstract

The dry-EDM process is environmentally neutral and enables to obtain good machining accuracy and relatively good surface quality. On the other hand, the application of dry-EDM is limited due to problems with the effective dissipation of heat from the machining zone and instability of material removal. The machining of Inconel 625 alloy was carried out in the carbon dioxide as a dielectric supplied to the machining gap through the channel in the working electrode, in the milling kinematics. In one of the investigated variants, the workpiece was submerged additionally in the deionized water during machining. The main aim of this research was to determine an influence of EDM milling in carbon dioxide with and without external workpiece cooling on the workpiece technological surface integrity ie. roughness, morphology and microhardness. The pulse time, current amplitude and gas pressure were selected as investigated parameters. Obtained results indicate significant differences in surface layer properties for both investigated machining variants.

Influence of material properties on near dry-EDM process: The discussion of research for titanium grade 2 and Inconel 625 alloy

“…The near-dry EDM milling was conducted on the research test stand equipped with electrodischarge generator MATRIX MPS -7163 160V/3A at the Cracow University of Technology [14]. The tool was tubular copper working electrode with an outer diameter of 1 mm.…”

“…Described below analysis was focused on comparison of selected aspects of surface integrity of Inconel 625 alloy and titanium Grade 2 after dry-EDM in the milling kinematics with external workpiece cooling such as: surface roughness parameters (measured with Taylor Hobson profilometer), SEM photographs and microhardness. The detailed research methodology and research devices which were used during this research were described in [14].…”

“…Due to the fact that during dry-EDM process it is still a problem with effective removal of heat from the machining gap, as well as workpiece material surface, adequate selection of process input parameters, dry-EDM is still limited to micromachining and is not used in industrial applications [14]. What is more one of the factors which has major impact on dry-EDM process it the workpiece material.…”

Experimental investigation on microhardness, surface roughness, and white layer thickness of dry EDM

“…While increasing argon gas pressure, the MH is significantly improved due to increased heat in the plasma zone and improved cooling and flushing efficiencies [30,31]. While increasing pulse width, the MH also improved with a 22.65% contribution due to increasing temperature in the plasma zone [32]. The maximum level of gas pressure (1.2 MPa) can be applied to obtain the highest MH.…”

“…The MH has been enhanced by increasing the gap voltage (39.365 percent contribution) between tools and work surfaces. However, after level 3, the MH is slightly decreased due to the reduced cooling efficiency caused by the complete burring of dielectric fluid [32,33]. The microhardness is significantly improved due to increased heat and the cooling effect of the dielectric medium (up to Level 3).…”