Thin-wall micromachining of Ti–6Al–4V using micro-wire electrical discharge machining process

Abstract

Machining of delicate thin members having extremely small thickness as compared to the other two dimensions is a precarious task when performed using conventional fabrication techniques. Non-contact machining process, such as micro-wire electrical discharge machining (micro-WEDM) process, an advanced means of machining, offers an appropriate way to machine thin-wall structures in an utmost precise manner. In the present work, thin-wall micromachining of Ti–6Al–4V is performed while utilizing the contactless, negligible thermal damage, and deformation-free nature of micro-WEDM process energized through the resistance–capacitance generator. The objective is to explore the feasibility of a minimum possible wall thickness. Performing the thin-wall micromachining using wire step-over approach, it is established that a wall of average thickness 8.47 µm with an end deflection and a wall of thickness about 15 µm free from end deflection is possible to fabricate using micro-WEDM process. It achieves a high aspect ratio of 70 corresponding to the minimum thickness of the wall. What’s more, a theoretical analysis is carried out to illustrate the functional relationship between wall-end deflection with workpieces’ thermophysical properties, discharge parameters, and the geometric parameters of the wall. Finally, the comparative assessment of wall-end deflection and volumetric material removal rate attained with three different materials, namely Ti–6Al–4V, mild steel, and SS-304, reveal that thermophysical properties of workpiece material play a critical role in determining the wall-end deflection and the resultant volumetric material removal rate.