Single-spark analysis of removal phenomenon in magnetic field assisted dry EDM

The increased MRR in magnetic field assisted dry EDM (by ∼130%) was attributed to several reasons including confinement of plasma due to Lorentz forces. The conjectures were investigated further by undertaking over 100 single-discharge, dry and liquid EDM trials, with and without magnetic fields, by varying current, voltage, magnetic field, pulse on-time and bi-pulse current. The magnetic field assistance increased the depth and reduced crater diameter by 80% in dry EDM; and reduced crater diameter marginally but significantly improved uniformity in the material erosion, in liquid EDM. The role of Lorentz forces in confining plasma and reduction in electron mean free path due to magnetic field, when modeled analytically, captured the experimental trends very well.