Advances in the experiment of ultrasonic and electrical discharge-assisted machining of titanium alloys: A systematic review

Titanium alloys, particularly Ti–6Al–4V, serve as fundamental materials in aerospace, automotive, and biomedical applications due to their exceptional strength-to-weight ratio and corrosion resistance. However, their inherent properties, specifically low thermal conductivity and high chemical reactivity, categorize them as difficult-to-machine materials, often leading to rapid tool degradation and compromised surface integrity in conventional manufacturing processes. These machining challenges have motivated extensive research into advanced hybrid techniques capable of addressing the limitations of traditional approaches. This comprehensive review provides a detailed analysis of Ultrasonic-Assisted Electrical Discharge Machining (UAEDM), a hybrid manufacturing technology designed to overcome the limitations of standalone Electrical Discharge Machining (EDM) and Ultrasonic-Assisted Machining (UAM). By synthesizing current experimental and theoretical data, this work evaluates the influence of ultrasonic fields on critical performance metrics, including Material Removal Rate (MRR), Electrode Wear Rate (EWR), and surface morphology. The review reveals that ultrasonic-induced cavitation and enhanced debris evacuation play pivotal roles in stabilizing the discharge gap, potentially increasing MRR while significantly reducing recast layer thickness and micro-crack density. Furthermore, this paper specifically reviews hybrid machining methods in ultrasonic-assisted EDM grinding, drilling, and turning, clearly identifying current research shortcomings and practical applications in aerospace. It also incorporates cutting-edge directions such as AI optimization and green sustainable machining, deeply exploring the synergistic effects of dielectric additives and cryogenic tool treatment on process efficiency and cost-effectiveness, pointing out potential pathways for performance optimization. Accordingly, this review provides unique insights by focusing on titanium alloys, clarifying the underlying mechanisms, and highlighting industrial applications and recent advances, offering a practical framework for high-precision and efficient titanium machining. It also identifies key research gaps in industrial scalability and AI-based real-time control, and outlines a roadmap for sustainable, high-performance machining. Solving these issues is critical to moving UAEDM from laboratory research into practical industrial applications.