Wire vibration, bowing, and breakage in wire electrical discharge machining

This article provides an analysis of the wire electrical discharge machinin g (EDM) process. The causes of wire vibration, bowing, and breakage are ide ntified. The cross sectional configuration of an eroded wire is derived fro m basic physics under the assumption that the erosion rate is constant. Thi s configuration is verified experimentally with further explanation as to w hy numerous experimental studies have yielded different configurations. A c omputational model has been developed that can evaluate the systematic effe cts that lead to wire breakage by determining the stress induced by wire er osion and the stress induced by the sparks during the operation of a wire-c utting EDM machine. This model is also capable of determining the extent of wire bowing and vibrations in these machines but only in the frontal direc tion. The model is supported by data from experiments performed on an AGIEC UT 612 wire machine cutting a 10 mm high copper bar with a 0.15 mm brass wi re to acquire wire breakage data. The nearly parabolic shape of the bowed w ire agrees with the results of other authors making more restrictive assump tions. (C) 2001 American Institute of Physics.