Metal removal, electrochemical machining

Electrochemical machining is a process based on the same principles used in electroplating except that the workpiece is the anode and the tool is the cathode. Electrolyte is pumped between the electrodes and a potential is applied, resulting in rapid removal of metal. 

Metal-recovery operations, phosgene in, 18 810-811. See also Metals recycling Metal reductions hydrazine, 13 569 to liquid metal, 16 141-146 Metal refining, 16 149-151 barium application, 3 349 limestone in, 15 38-39 Metal removal, in electrochemical machining, 9 593-595 Metal-rich phosphides, 19 59... 

Electrochemical machining (ECM) is a method of metal machining that aims at producing parts of specified shape, dimensions, and surface finish. The process is based on the removal of metal by electrochemical dissolution ([1-15] and references cited therein). Special machines have been developed to realize this aim. A complete ECM installation (Fig. 1) consists of the machine, the power supply, the electrolyte circulation system (tank, pump, heat exchanger, and sludge removal unit), and the control system (control of current, voltage, feed rate, gap width, and electrolyte temperature, pH value, pressure, and concentration short-circuit protection). 

Other nonconventional machining processes based on electrochemical metal removal are electrochemical machining, ECG, electrochemical polishing, and so on. 

Several electrochemically based methods are employed in the metals processing industry because of their ability to manufacture metal articles or components which are difficult or impossible to produce by traditional mechanical workshop techniques. The most important methods are electroforming and a group used for the controlled removal of metal, i.e. electrochemical machining, grinding and deburring. 

In electrochemical machining, the removal of the metal to form a hole or other feature is by anodic dissolution (Fig. 8.3). Clearly for the process to have the... 

Electrochemical machining is a recent innovation, the practice dating back less than twenty-five years. Much of the driving force for its development has come from the aerospace industry with its requirement to machine very hard alloys (e.g. those based on Ti and Fe/Co/Ni/Cr) to produce components able to perform a function reUably but also having minimum weight this specification often leads to components of very complex shape. The alloys which must be employed cause problems in conventional machining because of the low rate of metal removal and the short tool life. Electrochemical machining is, however, based on different properties of the metal independent of its hardness and it is only necessary to find an electrolyte where the alloy will dissolve anodically without passivation when the rate of metal removal may be estimated from Faraday s law. 

Electrochemical deburring is another modification of electrochemical machining carried out with smaller-scale ancillary and control equipment. It is used essentially to remove sharp corners and other imperfections and hence to finish metal components which have been manufactured by mechanical machining its... 

Electrochemical machining (ECM) is a metal removal process based on the laws of electrolysis. The need for ECM has stemmed from the recent development of high-strength heat-resistant alloys which are difficult to machine by conventional techniques. 

As well as influencing the rate of metal removal, the electrolytes also affect the quality of surface finish obtained in ECM, although other process conditions also have an effect. Depending on the metal being machined, some electrolytes leave an etched finish, caused by the non-specular reflection of light from crystal faces electrochemically dissolved at different rates. Sodium chloride electrolyte tends to produce an etched, matte finish with steels and nickel alloys a typical surface roughness would be about 1 pm Ra,... 

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