Improvement of electrochemical turning for machining complex shapes using a simple gap size sensor and a tubular shape tool

This paper presents the research and development of a new electrochemical machining technique, electrochemical turning (ECT), which can produce parts with complex shapes. In this technique, the electrolyte passes through a tubular electrode and is pumped to the workpiece. The actual dissolution is measured by using a new type of gap measuring and control sensor. In this sensor, the electrolyte between the tool and the workpiece becomes a resistance of a bridge circuit, while three other resistances are constant. Hence, if the gap size changes, the resistance of the electrolyte and consequently the voltage of the bridge change. This voltage can be used for measuring and control the gap size. Keeping the gap size in a constant value enables the machine to compare the actual and desired dimensions. A suitable ECT setup primarily consists of various components and subsystems, e.g., a mechanical machining unit, an electrical power and controlling system, an electrolyte flow system, etc. Some experiments were performed to identify the effects of voltage, gap size, and time on the material removal rate. As can be predicted, the removal rate increased with voltage and time and decreased with gap size. Also, surface roughness increased with voltage. More attempts will generate more possible applications for ECT.