Relationship between process parameters on the surface crack density in electrical discharge machining

This study investigates surface crack formation in electrical discharge machining (EDM), a critical issue affecting the reliability and lifespan of precision components made from tool steel. The research aims to evaluate how electrode material and machining parameters influence surface crack density on Mirrax plastic mold steel, a material with limited EDM focused studies. Three copper-based electrodes CuCoNiBe, CuNi2SiCr, and CuCr1Zr were tested under varying discharge currents (6–25 A), pulse-on times (50–200 µs), and pulse-off times (200–800 µs). Experiments were designed using a Taguchi L27 orthogonal array, and surface crack density was measured via scanning electron microscopy and image analysis. The results showed that higher current and longer pulse-off time reduced surface cracks, while longer pulse-on time increased them. CuCoNiBe yielded the lowest crack density (0.0005 µm/µm²), whereas CuCr1Zr resulted in the highest (0.0306 µm/µm²). Statistical analysis identified electrode type as the most significant factor. This work offers new insights by focusing on Mirrax steel and employing a robust experimental design. The findings contribute to optimizing EDM processes for better surface integrity in high-precision manufacturing applications.