Precision machining of high aspect-ratio rotational part with wire electro discharge machining

Abstract

Precision and micro rotational parts are widely used in various industries, such as micro probes for medical instruments, contact pins for micro assembly applications, micro electrodes for micro Electrical discharge machining (μ-EDM) or micro Electro-chemical discharge machining (μ-ECDM). In this research, a uniform annular area layer by layer feeding strategy was proposed to fabricate high aspect ratio, small radii rotational components on a conventional Wire electrical discharge machining (WEDM) machine equipped with an auxiliary spindle. The uniform annular area layer by layer feeding strategy consisted of the roughing and finishing stages. First, the theoretical Material removal rate (MRR) and radial infeed rate for each layer were determined for the roughing stage, and the theoretical surface roughness, Rz in the finishing stage was researched. Then, a series of optimization experiments were conducted to investigate the influence of the parameters on MRR and the machined surface roughness. A group of pin electrodes were machined by applying this feed strategy with the optimized parameters, and the minimum diameter of the pin electrodes was 40 μm with an aspect-ratio of 60. Finally, micro electrodes for an injection nozzle were achieved with this novel process and a qualified injection nozzle for powder metallurgy was fabricated with the machined micro electrodes.