Utilizing wire electrical discharge machining for surface quality and precise profile control of Inconel 718 fir-tree slot

In aeroengines, the fir-tree slot or tenon is a key component that connects the turbine disc and blades. Accordingly, it requires a high surface quality and highly precise contour machining. Wire electrical discharge machining (WEDM) offers highly precise machining, favorable surface quality, and vital machining flexibility, which are fundamentally advantageous for low-cost manufacturing of turbine disc tenon-slot structures. In this study, single-factor experiments and response surface methodology were employed to analyze the relationships between surface roughness (Rz), kerf width (K), pulse width, pulse interval, peak current, and voltage. In addition, predictive mathematical models describing how the surface roughness and kerf width are related to the discharge parameters were established. The maximum relative errors of the model predictions for the surface roughness and kerf width were only 4.55% and 7.03%, respectively, and they were distributed randomly. Combined with the prediction model, the offset of each time of multiple cuts was predicted and corrected. A 40-mm-thick superalloy Inconel 718 workpiece was used to machine a fir-tree slot structure with a surface roughness Ra of 0.432 μm, maximum recast layer thickness of 3.1 μm, and internal and external deviations of − 0.0089 mm and 0.009 mm, respectively.