Towards an Electrode Dressing-Free Micro Electrical Discharge Machining Approach for the Fabrication of Ellipse Dimple Textures

Abstract Micro-electrical discharge machining (micro-EDM) is a cost-effective method for the fabrication of micro surface textures with high accuracy. However, electrode wear (especially shape wear) remains a major challenge, which can lead to the deterioration of the replicated profile of the fabricated features. Conventional approaches to mitigating electrode shape wear involve interruptive electrode dressing using wire electrical discharge grinding (WEDG), which considerably increases the total machining time. To address this issue, this study proposes a novel dressing-free micro-EDM machining approach. Electrode shape wear experiments are first conducted for two representative fundamental machining modes (hole series drilling and layer-by-layer slot milling) to elucidate the electrode shape evolution law in micro-EDM. The electrode shape wear is found to follow a two-stage process—an initial rapid edge-rounding phase and a subsequent stabilization phase—where the electrode shape stabilizes to a steady elliptical or quadratic profile. Accordingly, a dressing-free ellipse dimple fabrication method is proposed, which leverages the stable worn electrode geometry (quadratic cross-section) in combination with a dedicated circular tool path design. A theoretical geometric-envelope analytical model is developed to predict the resulting stable ellipse texture long-axis dimension, achieving an average prediction error of 4%. This work represents a disruptive shift from traditional strategies for suppressing electrode shape wear using WEDG dressing toward exploiting it as a functional self-regulating shaping mechanism. This method can be employed to achieve continuous, dressing-free, mask-free, and highly efficient fabrication of ellipse dimples.