ABSTRACT
Machining of materials has been an important and highly useful process catering to the needs of humans. With the advent of new and novel materials, the conventional approaches to machining are no longer sufficient and the industry is continuously shifting from traditional to non traditional machining processes. The powder mixed wire electric discharge machining (pwEDM) is the modified version of the wire electric discharge machining (wEDM). In wEDM, powder is added into the dielectric fluid 2through mechanical stirring. The outputs obtained in pwEDM are largely dependent on the properties of the powder, which is added to the dielectric fluid. The physical, electrical, and thermal properties of powder play an important role in determining the material removal rate (MRR) and surface roughness (Ra) of the machined component.
This study is focused on reducing the surface roughness and increasing the material removal rate of the machined specimen (i.e., AISI 4140). In this experimentation graphite powder of particle size, 25 µm was added in the dielectric fluid. The main reasons behind the addition of graphite powder were its high thermal conductivity and low density. Owing to the high thermal conductivity, the graphite powder dissipates more heat from the cutting area, which reduces the crater size, as compared to the normal w-EDM. This phenomenon helps in improving the surface quality. Also, the low density of the graphite powder ensures that it mixes properly with the dielectric fluid.
The input process parameters considered in this experimentation are pulse on time (TON), pulse off time (TOFF), servo voltage (SV), wire feed (WF), and powder concentration (PC). The response variables that are considered in this experimentation are material removal rate (MRR), and surface roughness (Ra). The experiments were conducted as per the Taguchi methodology using the L27 orthogonal array.
It was observed that after the selection of parameters as per Taguchi methodology the surface roughness reduced by 49.51% and the material removal rate increased by 73.51%.
