Analyzing micromachining errors in EDM of Inconel 600 using various biodegradable dielectrics

Abstract

Inconel 600 is a Ni-based superalloy having exclusive properties like high strength and stability in harsh conditions. However, its accurate machining is challenging via conventional cutting methodologies. As a result, the use of electric discharge machining is common in cutting Inconel 600 precisely. But the intrinsic issue of overcut associated with traditional EDM limits its appreciation in cutting Ni-based alloy. Moreover, conventional dielectric oil used in EDM releases hazardous fumes and gases that put the operator’s health at risk. Therefore, in this study, six different biodegradable dielectrics have been investigated for their potential in controlling the dimensional overcut, which have yet to be evaluated thoroughly. The performance of biodegradable dielectrics (canola, amla, olive, sunflower, coconut, and mustard oil) against four types of electrode materials has been evaluated using full factorial design in the EDM of Inconel 600. Experimental findings are analyzed with statistical tests and optical/scanning electron microscopic evidence. The experimental results indicated that canola dielectric yield the smallest dimensional overcut. However, combination of sunflower oil and copper electrode proved as second premier case to reduce the overcut. Compared to the conventionally used kerosene oil, the biodegradable dielectrics (canola and sunflower) display a 63% and 1.2-folds reduction in overcut.

Role of biodegradable dielectrics toward tool wear and dimensional accuracy in Cu-mixed die sinking EDM of Inconel 600 for sustainable machining

“…The reason is that Olive oil has the lower value of dielectric strength (26-41 kV) among the other dielectrics used in this study, and thereof, the ionization of the said biodegradable oil becomes easier. This ionization phenomenon generates high discharge heat input in the cutting zone [50]. Correspondingly, larger amount of material is removed from the electrode and the target surface which promotes the EWR as indicated in Fig.…”

“…Therefore, the low C p generates less discharge heat during the pulse on time and high flash point of the biodegradable Mustard oil indicates the less volatility and flammability of the oil. Both these characteristics (low C p and high flash point of dielectric) contribute in lowering the value of EWR of Al [50]. Figure 5a shows the microscopic image at 0.5 g/100 ml C p in the Mustard oil, where shallow craters are formed on the surface of the machined electrode surface which is the indication of less erosion of material.…”

“…The Amla oil led to assist in the better cooling and heat dissipation to describe its supremacy concerning EWR. The reason for the lower EWR in the presence of Amla oil as compared to the Sunflower oil is due to the high dielectric strength of Amla oil (50 kV) which lowers the ionization of the dielectric and also minimizes the discharge heat for the erosion of material from the Al electrode [50]. Considering that the surface of the electrode remains intact owing to the low EWR thereof a better cut quality is achieved.…”

“…Figure 10a illustrates that a very thin and minute layer of melted debris was formed on the surface of Ni-based superalloy. The main reason for the formation of recast layer is that the particles are not completely removed out from the workpiece surface and redeposited on the workpiece's surface in the pulse-off time [50,58]. But as the feebler discharge has been produced in the cutting zone due to lesser concentration of Cu particles and high viscosity of the Sunflower oil.…”

Experimental investigation on micro ED milling of inconel alloy with SiC nano powder mixed Pongamia BD at different parametric condition

“…The results indicated that canola dielectric offered the smallest dimensional overcut. However, combination of sunflower oil and copper electrode proved as second premier case to reduce the overcut was reported [30]. The EDM performance of the hybrid composite (Al-SiC-Ni) was compared to that of three electrode materials (copper, brass, and graphite) and four bio-diesel-based biodielectrics such as Neem biodiesel (NBD), Jatropha biodiesel (JBD), Pongamia biodiesel (PBD), and Polanga biodiesel (POBD).…”