Influence of nozzle jet flushing on comer shape accuracy in wire EDM

In wire electrical discharge machining (EDM), wire brakeage often occurs and the shape accuracy tends to deteriorate when cutting corner shapes. However, the influence of jet flushing conditions on the debris exclusion and wire deflection in the comer shape cutting has not yet been investigated so far, while the influences of discharge conditions and spark distribution wire were studied. In this study, the flow fields and debris movements in the machined kerf during the comer shape cutting in lst-cut wire EDM were simulated by CFD analysis. Also, the wire deflection was discussed by a structural analysis of wire with stress distribution due to hydrodynamics force obtained by the CFD analysis. The results showed that the flow and pressure fields around the wire by jet flushing and the debris movements in the kerf significantly changed just after changing the cutting direction at the comer. Additionally, the comer shape error with wire deflection was experimentally measured and compared to the analytical result of wire deflection with hydrodynamics force. It was found that the influence of hydrodynamics force on wire deflection was as large as discharge explosive force under general 1st- cut conditions, which suggests that the influence of jet flushing on the corner shape accuracy is large under jet flushing conditions with relatively high flow rate.