Efficient fabrication of micro-circular pit arrays by EDM using wear-formed ellipsoidal tips of micro-prism electrode arrays

Micro-circular pit arrays are widely used to enhance the tribological and sealing performance of engineering surfaces. Although electrical discharge machining (EDM) is capable of fabricating such microstructures on electrically conductive materials, conventional approaches employing a single cylindrical electrode suffer from low machining efficiency and poor dimensional uniformity when producing dense pit arrays. This study proposes a novel EDM strategy that exploits a key geometric feature observed after micro-hole array machining with micro-prism electrode arrays: the cross-section of the electrode tip gradually evolves from a prismatic to a circular shape due to wear. By leveraging this wear-induced circular morphology, micro-circular pit arrays are directly replicated onto the workpiece surface using the worn micro-prism array electrode. Rather than mitigating electrode wear, the proposed method intentionally utilizes the degraded electrode as a functional tool. Experimental results on cemented carbide demonstrate that, under optimized process parameters (30% duty cycle, 4 μs pulse width, and 16.3 A peak current), the fabricated micro-pits have an average diameter of 273.99 μm and an average depth of 62.1 μm, with corresponding variances of 7.43 μm 2 and 4.46 μm 2 , respectively. Furthermore, the effects of electrical parameters on micro-circular pit arrays dimensional accuracy, surface roughness, crack characteristics, and burr formation are investigated. The proposed approach provides a highly versatile and efficient pathway for the fabrication of microstructure arrays on conductive materials.