GB1070912A - Improvements in or relating to process for the electrolytic and electro-chemical working of metals - Google Patents

Abstract

An electrolytic process for the working of metallic workpieces (including metallic carbide workpieces wherein the workpiece is employed as an electrode spaced apart from another electrode, there being relative motion between the electrodes towards one another during the working, material removal being effected by an electric current flowing through both electrodes through the intermediary of a non-corrosive electrolytic solution provided between the electrodes and having an essential component selected from the group consisting of water soluble fluorides and fluoro-compounds. A non-corrossive electrolytic solution is defined as one which in the absence of electric current removes substantially no material from the electrodes concerned in the process, e.g. a solution containing at least 4% by weight of KF. According to the materials to be worked, the electrolyte may be acidic, alkaline or neutral. Additional salts which may be included in the solution are nitrites, nitrates, phosphates, carbonates, sulphates or salts of organic acids or bases. The working may be by electrolytic grinding using an abrasive disc or wheel or by electrolytic sinking using an electrode and a feed-control mechanism to hold the gap between the electrode and workpiece constant. The electrolyzing current may have periodic pulses of opposite polarity to remove passive layers which build up on the anodic workpiece. Surfaces and edges not to be worked during electrolytic working may be protected by lacquers or coatings of good electron conductivity comprising electron conductive pigment such as graphite, carbon, metal or alloy powder and an organic or inorganic binding agent. The electrolytes used in deriving the graphs of the following Figures (not shown) contain 1) 15% by weight KNO3, 2) NaNO2-NaNO3 with organic additives, 3) NaNO2-NaH2PO4-sodium tetraborate, 4) 15% by weight of KF.