periodically swings backward and forward this soft plastic or liquid material is removed by the mechanically rubbing electrode 14 and then as electrode 14 swings back after a new arcing which is the consequence of the conductivity of the ions previously produced at the cutting point and still present there the next layers of the contact place are heated and again removed by the forward swinging electrode whereby the cutting process progresses because the current is interrupted during the phase of contact of electrode 14 and the cut place of workpiece 34 a short circuit between electrode 14 and workpiece 34 that would reduce efficiency is prevented the standing arc first directed between workpiece 34 and electrode 14 as soon as electrode 14 has cut deeper into workpiece 34 would circulate around electrode 14 because a plasma would develop between it and the workpiece 34 that surrounds it at the cut to prevent this and the loss of efficiency caused thereby the gas ions produced which alone allow development and maintenance of an arc because of their conductivity are continuously blown away by the compressed air or gas jet 42 that passes along through the workpiece cut to electrode 14 so that the arc cannot circulate about electrode 14 but remains standing directed between it and the cut place in question the swing of frame.