Correlation Analysis of the Topography and Wettability of SEDM Surfaces

Sink electrical discharge machining (SEDM) is widely employed for manufacturing molds and components with intricate geometries and high surface quality. Despite its versatility, the conventional characterization of EDM surfaces using the arithmetical mean roughness (Ra) fails to capture the detailed topographical variations that impact functional properties. This study investigates the influence of EDM discharge parameters on surface topography, particularly the mean groove width (RSm), and its correlation with surface wettability. Experiments were conducted on steel samples using two state of the art EDM machines with copper and graphite electrodes. Samples were fabricated with different roughnesses using standard and specialized EDM technologies designed to vary RSm independently of Ra. Surface characterization was performed through tactile and optical measurements, and wettability was assessed via drop shape analysis. The results reveal that RSm can be adjusted independently from Ra under specific conditions, offering greater control over surface functionality. A higher RSm value corresponded to a lower contact angle, indicating reduced wettability.