OBRABOTKAMETALLOV Vol. 27 No. 2 2025 technology Results and discussion The trials were conducted using the Taguchi analysis approach. ANOVA was used to identify the key components of the process. The MRR, SR and TWR calculated during the experiment are shown in Table 5. This table displays the outcomes of an electrical discharge machining (EDM) experiment, whereby the MRR, SR, together with TWR were evaluated using the Taguchi design of experiments. The trials were performed under different machining settings, and the associated S/N ratios were determined. The S/N ratio was used as a performance metric to determine the optimal machining parameters, with higher values preferred for MRR (“larger-the-better”) and lower values for TWR (“smaller-the-better”). Ta b l e 5 Trial results for MRR, SR and TWR Trail No. MRR (mm3/min) S/N ratio (dB) SR (µm) S/N ratio (dB) TWR (mm3/min) S/N ratio (dB) Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 Run 1 Run 2 Run 3 1 2,096 2,078 2,088 6,3917 2,238 2,244 2,242 7,0101 0,072 0,068 0,073 22,9708 2 4,456 4,556 4,667 13,1740 2,998 3,018 3,010 9,5675 0,109 0,113 0,111 19,0926 3 7,109 7,118 7,112 17,0411 3,704 3,716 3,712 11,3890 0,151 0,148 0,146 16,5744 4 4,011 3,948 3,923 11,9542 2,756 2,764 2,762 8,8203 0,048 0,054 0,052 25,7818 5 6,502 6,498 6,495 16,2560 3,404 3,398 3,406 10,6364 0,088 0,081 0,084 21,4750 6 4,168 4,145 4,152 12,3714 2,806 2,799 2,802 8,9504 0,242 0,234 0,239 12,4555 7 2,803 2,688 2,781 8,8055 2,794 2,786 2,792 8,9142 0,101 0,094 0,098 20,2013 8 3,328 3,336 3,329 10,4515 2,988 2,979 2,984 9,4950 0,159 0,154 0,161 16,0254 9 8,995 8,989 9,027 19,0883 3,026 3,032 3,029 9,6260 0,198 0,204 0,201 13,9354 10 3,098 3,108 3,102 9,8347 3,318 3,307 3,311 10,4018 0,044 0,039 0,041 27,6633 11 5,981 5,972 5,982 15,5316 2,648 2,654 2,652 8,4693 0,179 0,172 0,175 15,1215 12 6,256 6,259 6,266 15,9319 2,826 2,818 2,822 9,0111 0,221 0,227 0,223 13,0074 13 3,411 3,398 3,405 10,6415 2,898 2,896 2,902 9,2440 0,045 0,048 0,041 26,9825 14 3,081 3,075 3,085 9,7719 2,886 2,892 2,888 9,2140 0,176 0,172 0,179 15,1051 15 9,076 9,069 9,081 19,1572 3,002 2,992 2,988 9,5251 0,214 0,209 0,212 13,4865 16 2,805 2,803 2,798 8,9493 3,308 3,298 3,302 10,3773 0,081 0,074 0,072 22,4106 17 6,707 6,698 6,704 16,5254 2,762 2,766 2,758 8,8245 0,122 0,116 0,124 18,3648 18 6,031 6,022 6,026 15,6011 2,752 2,748 2,754 8,7909 0,258 0,262 0,254 11,7669 EDM operations heavily depend on MRR as the essential performance metric to measure material removal rate during specific periods. Each MRR measurement set contains three readings (MRR1, MRR2, MRR3), allowing S/N ratio calculation via their average value. The tests performed in Trial 15 (9.076 mm³/min) and Trial 9 (8.995 mm³/min) achieved peak MRR values, as their respective S/N ratios reached 19.1572 dB and 19.0883 dB. The results indicate that these particular machining parameters deliver high efficiency in material removal. Trial 1, along with Trial 16, exhibited the lowest MRR rates (2.096 mm³/min and 2.805 mm³/min, respectively), accompanied by S/N ratios that reached 6.3917 dB and 8.9493 dB. The obtained values indicate reduced performance in material removal tasks. The various results of MRR across trials point toward particular machining variables that directly affect the amount of material removed. From the experimental value of SR, it is evident that the finest surface finish (lowest roughness and highest S/N ratio) was obtained for Trial 1 (S/N ratio: −7.0101 dB), which produced the smoothest surface with roughness values of SR1 = 2.238 µm, SR2 = 2.244 µm, SR3 = 2.242 µm. This indicates that the optimized EDM parameters in this trial resulted in minimal surface defects and better surface integrity. The poorest surface finish (highest roughness and lowest S/N ratio) was obtained for Trial 3 (S/N ratio: −11.3890 dB), recorded the highest roughness values (SR1 = 3.704 µm, SR2 = 3.716 µm, SR3 = 3.712 µm), leading to a poor-quality surface. This may be due to high discharge energy, excessive tool wear, or increased thermal stress causing deep craters and microcracks. Surface roughness values range from 2.238
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