Method and apparatus for fast hole electrical discharge machining
 A fast hole drilling EDM electrode and a more efficient apparatus and method for electrical discharge machining using the electrode. The electrode has an electrically conductive body with a leading end or tip and a length of relatively uniform non-circular cross-section that is operatively adapted to provide a dielectric flush path between the electrode body and the hole being machined in the workpiece. At least one dielectric supply bore is formed lengthwise through the body. The one or more supply bores connect a dielectric exit at the leading end of the body with a dielectric entrance located distally therefrom. This electrode is operatively adapted for being rotated during the machining process and for its non-circular cross-section to form a hole with a circular cross-section, when so rotated. During machining, a suitable dielectric fluid is supplied to the dielectric entrance of the electrode under sufficient pressure to force the dielectric through the one or more supply bores and out the dielectric exit to flush the eroded material through the dielectric flush path and out of the hole being drilled. With the present invention, a hole in a workpiece can be machined at faster rates, while still maintaining the surface quality and dimensional precision expected from an EDM apparatus and method. 
Ford Motor Company
B B
B23H B23H
inventional inventional
Larry A. Michael J.
Peterson Habel