# Principles and Characteristics of Different EDM Processes in Machining Tool and Die Steels
## 4 Research in EDM of Tool Steel
### Performance Measures in EDM of Tool Steels  
Extensive literature is available relating the effect of the working parameters on the performance measures during the EDM process of tool steels. Some even introduced many techniques to improve process performance measures. Accordingly, [PERSON] and [PERSON] [118] studied the influence of current, pulse-on time, die electric pressure, and tool diameter on the output response in terms of MRR, TWR, and SR of EN8 and D3 steel materials machined in EDM process. The study utilized response surface methodology (RSM) to analyze parameters and applied analysis of variance (ANOVA) to identify significant process parameters. Cast copper and sintered powder metallurgy coppers were considered as tool electrodes to machine the two workpieces. The authors reported that coefficient of determinant values were above 0.90 for both materials, and the predicted value reasonably agreed with adjusted values. Furthermore, the mean value of MRR for EN8 material was higher (72.4 mm\({}^{3}\)/min) and that of TWR was lower (12.73 mm\({}^{3}\)/min) for cast electrode compared to sintered electrode. It was found that the SR value was marginally lower with sintered electrode than with cast electrode. Moreover, the mean value of MRR was higher and that of TWR was lower when machining D3 using a cast electrode compared to a sintered electrode. Furthermore, [PERSON] et al. [107] proposed an optimization methodology to select the best process parameters in a multi-response situation. Experiments for AISI D2 steel machining were conducted on a die sinking EDM under different combinations of process parameters. The study adopted RSM to find the influence of process parameters including discharge current, pulse-on time, duty factor, and flushing pressure on four response parameters, namely, MRR, TWR, SR, and circularity (r\({}_{1}\)/r\({}_{2}\)) of the machined component. A mathematical tool was included as a decision-making unit to obtain the relative efficiency for each experimental run, and the decision-making unit was evaluated by the LINGO system. The authors \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{4}{c}{**EDM Process**} \\ \cline{2-5}  & **D-S EDM** & **W EDM** & **\# EDM** & **P-M EDM** & **D EDM** \\ \hline Objective 1 & [23,74,105,107,118, 126,139,157,161, 164,170,182,186, 188,192–197] & [54,119,121,122, 142,177,178,190, 198] & [132] & [61,116,135,154, 158] & [103,115,152, 159,177,178] \\ \hline Objective 2 & [91,104,105,124,141, 145,146,168,174, 182,184,199–201] & [122,134,148,149, 172,190,202] & [116,131] & [165] \\ \hline Objective 3 & [85,162,180,188,195, 197,203,204] & [111,119,198] & [132,205, 206] & [128,135,153] & [152] \\ \hline Objective 4 & [106,109,110,126, 139,140,162, 171,193,201,207–209] & [113,121,175] & [166] & [103,114] \\ \hline Objective 5 & [162,182,192,196, 210,211] & [185] & & \\ \hline Objective 6 & [141,157,212] & [206] & [135] & [78,127,165] \\ \hline Objective 7 & [74,76] & & [61,129,130,136, 155,158] & [115,159] \\ \hline Objective 8 & [108,112,144,147, 169] & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Studies for different grades of tool steel machined using various EDM processes. D-S—die sinking; W—wire; \(\mu\)—micro; P-M—powder-mixed; D—dry. reported the optimal setting combination as Ip (discharge current) of 7 A, Ton (pulse-on time) of 200 \(\upmu\)s, \(\tau\) (duty factor) of 90%, and Fp (flushing pressure) of 0.4 kg/cm\({}^{2}\), and the experimental values of responses were obtained as MRR of 13.9600 mm\({}^{3}\)/min, TWR of 0.0201 mm\({}^{3}\)/min, SR = 4.9300 \(\upmu\)m, and circularity = 0.8401. Furthermore, [PERSON] and [PERSON] [119] studied the influence of machining parameters on the MRR in the cylindrical wire electrical discharge turning process. A statistical design of the experimental method was utilized to study AISI D3 (DIN X210 Cr12) tool steel.