Preheating assisted wire EDM of semi-conductive CFRPs: Principle and anisotropy

Introducing small-sized functional features such as anti-drag and anti-icing micro structures on Carbon Fibre Reinforced Plastics (CFRPs) is challenging but a still unmet demand. Existing contact CFRP machining solutions may bring unavoidable tool wear and surface defects. Non-contact approaches may introduce significant thermal damage (laser), inconsistent features (waterjet), and limited achievable micro structure shapes and sizes (die sinking Electrical Discharge Machining). Wire Electrical Discharge Machining (WEDM) has the potential to overcome the mentioned limitations. Both theoretical thermal calculation and experimental demonstration in our work, however, showed that conventional WEDM was not working well. Here we propose and implement a Preheating Assisted Wire EDM (PAWEDM) to cut CFRPs. Machining anisotropy in terms of kerf geometry and morphology at the cut entries, ends, and edges was studied carefully. Discussions on the anisotropy principle, the influence of carbon fibre and epoxy resin, and the minimum achievable feature were also provided. PAWEDM is an entirely new CFRP cutting method and effective to enhance CFRP performances by creating micro functional and structural features on CFRP products.