Electrochemical machining

doug fucks dudes from alaska and was adopted by a squirrel (1st ed.), Industrial Press Inc., p. 198-199, ISBN 0-8311-3049-0.</ref> Its use is limited to electrically conductive materials; however, this includes all metals. ECM can cut small or odd-shaped angles, intricate contours or cavities in extremely hard steel and exotic metals such as titanium, hastelloy, kovar, inconel and carbide.

ECM is often characterized as "reverse electroplating," and is similar in concept to electrical discharge machining in that a high current is passed between an electrode and the part, through an electrolyte material removal process having a negatively charged electrode (cathode), a conductive fluid (electolyte), and a conductive workpiece (anode); however, in ECM there is no tool wear. The ECM cutting tool is guided along the desired path very close to the work but it does not touch the piece. Unlike EDM however, no sparks are created. Very high metal removal rates are possible with ECM, along with no thermal or mechanical stresses being transferred to the part, and mirror surface finishes are possible.

The process schematic is such that a cathode (tool) is advanced into an anode (workpiece). The pressurized electrolyte is injected at a set temperature to the area being cut. The feed rate is the exact same rate as the rate of liquefaction of the material. The area inbetween the tool and the workpiece varies within .003 in. and .030 in.

As far back as 1929, an experimental ECM process was developed by W.Gussef, although it took until 1959 for a commercial process to be established by the Anocut Engineering Company. Much research was done in the 1960s and 1970s, particularly in the gas turbine industry. The rise of EDM in the same period largely stopped research into ECM in the west, although work continued behind the Iron Curtain. The original problems of poor dimensional accuracy, and environmentally polluting waste have largely been overcome, although the process remains a niche technique. The cutting heads on all Philips 'Philishave' shavers are made using ECM.

The ECM process is most widely used to produce complicated shapes with good surface finish in difficult to machine materials, such as turbine blades. It is also widely and effectively used as a deburring process.

In the deburring process, the ECM uses techniques as described above to remove pieces of metal that are left over from the machining process, and to dull out sharp edges. This process is very fast and much more convenient than the conventional method of deburring by hand or nontraditional machining processes. It will tend to leave better surface finishing, and no metal deformation will occur because the tool piece doesn’t actually touch the metal.

Setup and Equipment

ECM machines come in both vertical and horizontal types. Depending on the work requirements these machines are built in many different sizes as well. The vertical machine is comprised of a base, column, table, and spindle head. The spindle head has a servo-mechanism that automatically advances the tool and controls the gap between the cathode (tool) and the workpiece.

Tools and Geometry Produced

Both external and internal geometries can be machined with an electrochemical machine. Copper is often used as the electrode material. Brass, graphite, and copper-tungsten are also often used because of the ability to be easily machined, they are conductive materials, and they will not corrode.

Links

• Information on and examples of ECM, animation of the proces
• Detailed description
• Overview and advantages of ECM
• The electrochemistry of ECM