Reduction of stray-current attack in electrochemical machining

Abstract

Stray current effects in electrochemical machining promote inferior surface finishes and poor dimensional tolerances. A study of the problem has been made using a segmented anode to measure weight losses in the stray current region as a function of chloride ion concentration. At intermediate chloride concentrations, the attack can be decreased by the formation of a passive film, but this effect is marred by heavy pitting. The growth of these pits has been retarded by the addition of anions that are capable of forming insoluble compounds in the pits. These additions can be made to chloride solutions in such a concentration that stray current attack is reduced but machining is not affected.