Method of and apparatus for cutting narrow grooves

A method of cutting a narrow groove in a workpiece formed of an electrically conductive material, said method comprising the steps of

• providing an electrode disk formed of an electrically conductive material and having a continuous circular peripheral edge,
• providing openings positioned radially inwardly from said continuous peripheral edge and extending axially inwardly from each major side of the disk toward the other major side,
• rotating the electrode disk about its central axis,
• establishing an electrical potential between the electrode disk and the workpiece,
• establishing a flow of electrolyte between the electrode disk and the workpiece,
• effecting relative movement between the rotating electrode disk and workpiece to bring them into close proximity,
• establishing a flow of electrical current between the rotating electrode disk and the workpiece to initiate formation by electro-chemical action of a groove in the workpiece,
• continuing the formation of the groove by continuing the movement of the rotating electrode disk and workpiece relative to each other to move the major sides of the electrode disk and side surfaces of the groove into an overlapping relationship,
• establishing a flow of electrical current between the side surfaces of the groove and major sides of the rotating electrode disk during continued formation of the groove,
• and moving the openings in the rotating electrode disk along the side surfaces of the groove to reduce the electrical current density between the side surfaces of the groove and the major sides of the electrode disk.