Study of Vibration Assisted Inclined feed Micro-EDM Drilling

Abstract

Transport of the fresh dielectric fluid into the discharge gap as well as debris removal from the hole becomes more difficult and essential in micro-EDM deep hole drilling. To solve this problem horizontal-feeding of electrode in EDM drilling of micro hole had been investigated, but the depth of hole which can be drilled is still very limited. An approach of micro-EDM drilling by inclined feeding of the electrode incorporated with vibration of the electrode in the longitudinal direction is proposed and implemented. It is found that either inclined feeding or axial vibration of the electrode leads to an increase of the depth of the hole being drilled as compared with horizontal-feeding method. A significant improvement is obtained when both are applied simultaneously. The depth of hole is increased by 75% when the aluminum alloy 6061 is drilled by a 200μm in diameter electrode using a 10-degrees downward electrode feeding together with the axial vibration having the frequency and amplitude of 250Hz, and 5μm, respectively. The maximum aspect ratio achievable is 24 in this case. It is 26 for the stainless steel drilled by a 100μm in diameter electrode, and 18 when the size of electrode is reduced to 50μm in diameter.