Analysis and Design of Wire Transport System in Microwire-Electronic Discharge Machining

A dynamic model for analyzing the wire transport system of micro w-EDM (wire electronic discharge machining) is proposed. Based on the model, two mechanisms are proposed to stabilize the wire tension. The first mechanism is the active wire feed apparatus where the wire spool is fed by a motor actively, instead of passively pulled by the windup motor. Hence, the inertia loading of the wire spool can be isolated from the system. The second mechanism is mounting a multilayer damped vibration absorber (MDVA) on the system. As the wire tension variation occurs, the MDVA oscillates to attenuate the wire tension variation. The performances of both mechanisms on the wire tension variation are theoretically investigated and experimentally validated through corner cutting on the 1.0 mm thickness tungsten carbide. Results show that the wire tension variation can be reduced from 10.3 gf to 3.3 gf after mounting the active wire feed apparatus and the oscillation frequency is increased from 13 Hz to 21 Hz. The wire tension variation can be further reduced to 1.9 gf after mounting the MDVA on the system and the high frequency perturbation is significantly attenuated. The 30-deg corner cutting shows that the corner error are significantly reduced from 26.0 μm to 12.0 μm; the standard deviation of kerf is reduced from 4.34 μm to 0.96 μm, and the surface roughness Ra is reduced from 1.15 μm to 0.63 μm after employing both developed mechanisms.