Microstructural analysis and multi response optimization of WEDM of Inconel 825 using RSM based desirability approach

Increasing demand of aerospace industry for more heat resistant and tough material have open up the possibility of the use of Inconel 825 for making of combustor casing and turbine blades. Because of its robust nature, Inconel 825 is a difficult-to-cut material with conventional methods. Wire-cut electrical discharge machining (WEDM), a non traditional method uses thermoelectric erosion principle to produce intricate shape and profiles of such difficult-to-cut material. In this study, various operating parameters of WEDM are optimized using desirability approach and microstructural behavior at optimum combinations was studied. Input parameters viz. pulse-on time, pulse-off time, peak current, spark gap voltage, wire tension, wire feed and performance has been measured in term of material removal rate, surface roughness and wire wear ratio. It has been observed that at 110 machine unit pulse-on time (T-on), 35 machine unit pulse-off time (T-off), 46 volt gap voltage (SV), 120 ampere peak current (IP), 11 machine unit wire tension (WT) and 5 m/min wire feed (WF), the values obtained for material removal rate (MRR), surface roughness (SR) and wire wear ratio (WWR) were 27.691 mm(2)/min, 2.721 mu m and 0.117 respectively. Scanning electron microscopy, energy dispersive spectrograph and X-ray diffraction analysis has also been carried out to study the surface characterization. Comparatively less numbers of cracks, pockmarks, craters, and pulled out material were found on work specimen surface and wire electrode surface under standardized conditions, thus maintaining the surface integrity of the machined surface.