Enhancement of EDM performance in high-aspect ratio slots for turbomachinery by planetary motion of the electrode

Abstract

Electrical discharge machining (EDM) is regarded as the most competitive solution for the machining of high-aspect ratio cavities with strict requirements in surface quality and accuracy. The diversity of applications ranges from the plastic injection mold industry to the manufacturing of turbine components. The cooling holes in vanes and blades and the seal slots in nozzle guide vanes (NGV) are demanding geometries in the aerospace sector usually processed by EDM.The nature of the material removal in EDM, developed without any contact with the part, is considered a major advantage when difficult to manufacture superalloys are involved. However, in high-aspect ratio cavities, due to debris accumulation in the narrow gap, the machining stability is limited with the machining depth. This productivity limitation has been a matter of industrial and scientific research.Considering that the key requirements in aerospace industry are quality and machining performance, this study proposes different machining strategies with the objective of enhancing the productivity of high-aspect ratio slots in Nickel base C1023 super-alloy. Results demonstrate that planetary motion of electrode during the machining process is a promising industrial solution for enhancing machining productivity of the slots machining in the lateral faces of NGV turbine components.