Electrochemical machining of ferritic steels - where pulsed direct current increases material removal and improves surface finish

摘要

Process for the electrochemical machining of metals esp. for sinking holes in ferritic steels using direct current between the tool and the workpiece which each form an electrode in an electrolyte, pref. sodium nitrate. Specifically pulsating direct current is used between the electrodes and the working voltage pref. has a ripple of =20% and pulse frequency 5 Hz to 300 HzM both the ripple and the pulse frequency being adjustable during machining. The min. values of the pulsed voltage is pref. is not 4 volts, and is esp. zero volts. The pulsed D.C may be applied only in the end phase of machining to polish the surface. The working voltage is pref. obtd. from a thyristor-controlled generator. In the machining of a low carbon steel, or a steel contg. 13% Cr, 0.15 % C and used for turbine blades, the electrical energy consumed is reduced and surface finish improved.