“…The gap between wheel and electrode (graphite [10,[13][14][15][16], copper [14,16] or brass [15]) is occupied by a dielectric fluid that allows re-establishing the optimum conditions after each spark. Different dielectric fluids have been used: oil [10], emulsions [12][13][14][15], compressed air and no fluid [13]. The process has been applied mainly to diamond wheels of small grit size (up to 4000# [15]), which are used for super-finishing operations.…”