On controlling of gas film shape in electrochemical discharge machining process for fabrication of elliptical holes

Abstract

ABSTRACT In the Electrochemical discharge machining (ECDM) process, the geometry and quality of the desired feature mainly depend on the thickness and structure of the gas film over the tool electrode, respectively. In order to machine various arbitrary-shaped profiles, control over the gas film shape is necessary for the ECDM process. The present research work deals with controlling the gas film shape by controlling the applied electrostatic force acting on the gas bubbles during the machining process. This was achieved by maintaining an appropriate inter-electrode gap (IEG) and applied energy. A mathematical model was drawn to establish the relationship between IEG, applied energy, and electrostatic force. Based on the magnitude of electrostatic force acting on gas bubbles, IEG was divided into two zones by considering the effect of the sphere of influence on the gas bubble. High-speed images and experimental evidence were used to validate the mathematical model. Hole over the cut (HOC), hole deviation, and hole depth was considered as output characteristics. An elliptical hole with a hole deviation of 60.08%, HOC of 75 mm, and 420 µm hole depth was achieved. With the optimal parametric setting at various counter electrode positions, elliptical holes of different orientations were fabricated.