OBRABOTKAMETALLOV technology Vol. 27 No. 2 2025 Ta b l e 1 1 Optimal setting parameter for raw data Sl.No Parameter Description 1 WEC Level 4219 (best wire composition) 2 Ig Level 16 (higher discharge current) 3 Vg Level 40 (lower gap voltage) 4 Ton Level 38 (longer pulse-on time) 5 Toff Level 5 (shorter pulse-off time) Pulse-off time (Toff) (Levels: 5, 7, 9): the mean utility value decreases as pulse-off time increases. Shorter pulse-off time (5 µs) maximizes utility, likely due to reduced idle time and increased machining efficiency. Longer pulse-off times (9 µs) reduce performance, possibly because of decreased spark frequency. ECW level 4219 is identified as the most suitable wire composition for achieving optimal performance. Gap voltage (Vg) has the most significant influence, with lower levels contributing to better utility values, underscoring the need for stable discharge conditions during machining. Gap current (Ig) and pulse-on time (Ton) must be optimized to achieve faster material removal and improved efficiency. Shorter pulse-off times (Toff) help maintain spark continuity, increasing machining effectiveness. The optimal parameter settings for raw data are summarized in Table 11. Ta b l e 1 2 ANOVA for utility function (UMRR, SR, TWR) for raw data Source DoF Seq SS Adj SS Adj MS F-ratio P-values % contribution Ig 2 0.4007 0.4007 0.20037 3.94 0.051 4.767 Vg 2 7.2282 7.2282 3.61411 71.05 0.000 85.984 Toff 2 0.2179 0.2179 0.10894 2.14 0.164 2.593 Residual error 11 0.5595 0.5595 0.05087 – – 6.656 Total 17 8.4064 – – – – 100 S = 0.2255 R-Sq = 93.3 % R-Sq(adj) = 89.7 % Table 12 presents the pooled analysis of variance (ANOVA) for the utility function (U), which integrates multiple responses from the EDM experiments, including material removal rate (MRR), surface roughness (SR), and tool wear rate (TWR). The independent variables affecting the utility function are gap current (Ig), gap voltage (Vg), and pulse-off time (Toff). The table includes the following statistical terms: – Degree of freedom (DoF) is the number of independent ways a factor can vary; – Sequential sum of squares (Seq SS) is the total variation contributed by each factor; – Adjusted sum of squares (Adj SS) is the sum of squares adjusted for other model terms or interactions; – Adjusted mean square (Adj MS) is the variance of each factor, calculated as Adj SS divided by DoF; – F-ratio is the ratio of factor variance to residual variance; higher values indicate stronger influence; – P-value is the indicates statistical significance; values less than 0.05 denote significant effects; – Percentage contribution is the proportion of total variation explained by each factor.
RkJQdWJsaXNoZXIy MTk0ODM1