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Short history of electrochemical machining (ECM) development

The electrochemical machining (ECM), as a technological method, originated from the process of electrolytic polishing offered already in 1911 by well-known Russian chemist E.Shpitalsky.

In the beginning of the 20th century, researchers in Russia, Western Europe, and the USA offered various ways and technological schemes of ECM application for dimensional processing of parts, mainly on operations of contouring and internal push broaching of various forms.

In 1928, the technological ECM scheme known at this time was essentially improved by the Russian engineers V.N.Gusev and L.Rozhkov, due to compulsory intensive flushing of electrolyte fluid through interelectrode space and the EDM electrode moving (feeding) with velocity equal to velocity of anode dissolution. It allowed to increase current density and to reduce working interelectrode gaps and, accordingly, to raise target technological indicators of the ECM (accuracy, quality of the surface and productivity).

The "traditional" model of the electrochemical processing, which had the greatest distribution in 50 – 70 years of the last century, assumed the direct current usage and continuous feed of the EDM electrode and, as a rule, activating electrolyte fluids (water solutions of halogenous salts of alkaline metals — NaCl, KCl, KBr, etc.). Practical realisation of such methods caused rather small working current density (10 … 40 A/cm ²), and considerable interelectrode gaps (0,05 … 0,3 mm), not allowing to achieve competitive high accuracy of processing and quality of the surface.

In 1959 for the first time the Anocut Engineering Company, USA introduced into production the traditional model of the ECM using the direct current at the production run equipment.

In 1960-1970s serial use of the ECM in aerospace branch (industry), in tool manufacture (forging dies) was began in the USSR and in the Western Europe. Electrochemical technologies developed during this period and such well-known firms as Philips, Hitachi, Mitsubishi, AEG Eloteherm, Amchem, etc made the equipment.

In 80 – 90s more perfect schemes of impulse and impulse-cyclic processing in passivating oxygen-containing electrolyte fluids (water solutions of NaNO3, ÊNO3, NaClO3, Na2SO4, etc.) were developed, which allowed to lower an error of processing to 0,02 … 0,05 mm and surface roughness to Ra 0,2 … 0,4 micron.

However, in connection with occurrence in hi-tech industries (precision instruments industry, medicine and medical equipment, aircraft engine-building, etc.) new groups of high-duty and hard materials (including nanostructure materials), complication of the form of parts and toughening of requirements to the quality of a facial layer, the necessity for new technologies in electro-physical and electrochemical processing has arisen.

Reaction to this demand of technical progress was appearance in 1998 — 2011 of the whole complex of new bipolar microsecond ECM by vibrating EDM-electrode. A special feature of these methods consists in that they are carried out at super small (3 … 10 micron) interelectrode gaps using the groups of impulses of high density current (about 10² … 104 À/ cm²).

At their realisation you can achieve small errors (0,001. 0,005 mm) of processing, creation on parts surfaces of regular macro- and micro-reliefs with micron and submicron range, and receiving of optically smooth surfaces (Ra 0,1. 0,01 micron). All this is accompanied by essentially higher (in comparison with competing technologies) productivity at finishing operations.

New ways of microsecond electrochemical processing are protected by tens of patents and make a basis of original electrochemical technology and equipment (machines of the "ET" series), developed and created by a group of Ufa engineers and scientists and manufactured serially by ECM, LLC.