Post-cast EDM method for reducing the thickness of a turbine nozzle wall

The present invention relates to a method of using electrodischarge machining apparatus for reducing the thickness of turbine nozzle walls and particularly to a post-cast operation using EDM apparatus to remove material from an interior wall of a cavity extending within and between opposite ends of the nozzle to reduce thermal stresses and improve casting yields. A post-cast EDM process is used to remove material from the interior surface of a nozzle vane cavity of a turbine. A thin electrode is passed through the cavity between opposite ends of the nozzle vane and displaced along the interior nozzle wall to remove the material along a predetermined path, thus reducing the thickness of the wall between the cavity and the external surface of the nozzle. In another form, an EDM process employing a profile as an electrode is disposed in the cavity and advanced against the wall to remove material from the wall until the final wall thickness is achieved, with the interior wall surface being complementary to the profile surface.