Multi-objective optimization and Surface Morphology of M-42 AISI Steel Using Normal and Cryo-treated Brass Wire in Wire Cut EDM

Super-hard high-temperature resistant M-42 that is best cobalt steel with high hardness and hot strength finds the application in manufacturing of twist drills, milling cutters, taps, reamers, broaches etc. The wire cut EDM process was seen as a decent option over conventional machining forms. In this research work, the effect of normal brass wire (N-bw) and cryo-treated brass wire (CTbw) on M-42 steel was investigated experimentally and analytically. A shallow cryogenic treatment (- 110 degrees C) is given to normal brass wire (N-bw) which was set at (4-8-4 cycle). Further it was also compared the regression analysis of process parameters of wire cut EDM with well-known design of experiment approach called response surface methodology. The parameters pulse on time (T-on), pulse off time (T-off), spark gap voltage (SV) and wire feed (W-F) have been selected as input parameters. The output attributes have been measured in terms of cutting speed (CS) and surface roughness (SR). The use of normal brass wire (N-bw), the cutting speed (CS) and surface roughness (SR) was increased by 98% and 41%. After using shallow cryogenic treatment, the electrical conductivity of the cryo-treated brass wire (CTbw) was improved the performance of wire cut EDM. As a result, both the cutting speed (CS) and surface roughness (SR) were improved by 102% and 35%. From surface morphology, the machined surface was observed with uniform craters, no micro-cracks and less debris after cryogenic treatment.