Investigation of welding bridge occurrence and short circuit impact on wire breakages during WEDM

Abstract

The paper provides the results of a short circuit impact on wire breakages during wire electrical discharge machining (WEDM) of AISI 9840 steel by the SODICK VZ300L machine. A method of scanning electron microscopy (SEM) is used for debris size, morphology and shape analysis. The carried out investigation led to the conclusion that the most probable reason of the welding bridge formation is due to the non-spherical (conglomerates) particles' presence with a large number of surface irregularities in a dielectric liquid. A classification of debris particles is proposed from the point of view of their dimensions and ability to overlap the spark gap - effective and ineffective particles.