Investigation and optimization process of powder-suspended electro-discharge machining for machining attributes of SKD11 steel
Manh-Tung Do, Van-Tao Le, Long Hoang, Truong-Giang Nguyen, Ngoc-Quy Nguyen, Ba-Bao NguyenAbstract
This study investigates the machinability performance of powder-mixed electrical discharge machining (PMEDM) under the impact of processing parameters, including peak current ( I p ), pulse-on time ( T on ), and powder concentration ( A p ) for SKD11 steel. The machining responses considered were material removal rate (MRR), tool wear rate (TWR), and surface roughness ( R a ). To evaluate and predict machining performance, regression models for MRR, TWR, and R a were developed and validated using analysis of variance to ensure their adequacy and statistical significance. Subsequently, two multi-criteria decision-making approaches – desirability approach (DA) and multi-objective optimization on the basis of ratio analysis (MOORA) – were employed to find the optimum processing conditions. The results indicate that I p exerts the most significant impact on MRR and TWR, whereas T on predominantly affects R a . Secondary effects were attributed to T on and A p for TWR and MRR and to I p and A p for R a . The DA method identified the optimal parameters as I p = 8 A, T on = 50 µs, and A p = 10 g/L, yielding MRR = 4.117 mg/min, TWR = 0.7159 mg/min, and R a = 1.87 µm. In contrast, MOORA suggested I p = 4 A, T on = 100 µs, and A p = 10 g/L as the optimal setting, with MRR = 3.4707 mg/min, TWR = 0.3451 mg/min, and R a = 2.02 µm. Compared with MOORA, the DA approach improved MRR by 18.62% and dropped R a by 7.43% while increasing TWR by 107.45%. In addition, surface integrity characteristics, including defect formation and recast layer thickness, were examined under the optimal conditions of both optimization techniques. The findings confirm that the DA method provides superior overall performance in terms of productivity and surface quality for PMEDM of SKD11 steel under the investigated conditions.