An Adaptive Electrical Discharge Machining System for Efficient and High-Quality Machining of Curved Superalloys with Thermal Barrier Coatings

Electrical discharge machining (EDM) of thermal barrier coatings (TBCs) on curved superalloy components faces substantial challenges. These challenges stem from the significant material property mismatch between ceramic coatings and metallic substrates, as well as the effect of workpiece curvature. Conventional fixed-parameter control can cause coating ablation, entrance edge chipping, wall microcracking, and interfacial delamination. This study develops an adaptive EDM control system integrating high-speed discharge state detection and intelligent parameter adjustment. A discharge-state classification method based on voltage thresholds, discharge delay time, and discharge duration is adopted in this system. With a field-programmable gate array (FPGA) controller possessing nanosecond-level response speed and after hardware delay is considered, real-time state identification is achieved on the microsecond timescale. The relative high-resistance spark rate (RHSR) is introduced as a machining progress indicator to distinguish machining stages. According to the identified machining stage and discharge state, the electrical parameters, arc plasma energy control, short-circuit interruption, and electrode servo motion are adjusted adaptively. Comparative experiments show that the proposed strategy markedly reduces carbon deposition, suppresses entrance flaring and edge chipping, decreases wall microcracking, and prevents interfacial delamination while maintaining machining efficiency comparable to conventional fixed-parameter machining.