Why is Inconel hard to machine?
The properties of Inconel 718 superalloy are used to manufacture aircraft components; its properties, including high hardness and toughness, create processing difficulties when using traditional methods. To avoid this, unconventional techniques are used, of which electrical discharge machining (EDM) is a good option.
However, the nature of material removal using the EDM process results in Inconel 718 having thermophysical properties that hinder its machinability; therefore, a more extensive analysis of the impact of these properties on the EDM process is needed, with a wider range of process parameters used The machinability of this material is analyzed within the scope. In this study, we investigated the use of EDM processes for drilling microholes in Inconel 718 superalloy. An experiment was conducted to evaluate the effect of five process parameters (open circuit voltage, pulse time, current amplitude, inlet dielectric fluid pressure, and tube electrode rotation) with a wide range of values on process performance (drilling speed, linear tool wear, side gap thickness and hole aspect ratio). Analysis shows that the thermal conductivity of this superalloy significantly affects the effectiveness of drilling. The combination of higher current amplitude (I ≥ 3.99 A) and extended pulse time (ton ≥ 550 µs) provides satisfactory hole accuracy (side gap thickness ≤ 100 µm), uniformity of hole entrance edge, and There is no need to re-cure the material and the aspect ratio is approximately 19. Obtaining holes with high dimensional shape accuracy has a huge impact on their usability in the construction of components in the aerospace industry.
