1. Electro Chemical Machining
Fig : Schematic illustration of the electrochemical-machining process. This process is the reverse of electroplating.

2. Electrochemical machining
This process is reversal of the electro plating
Electrolyte acts as current carrier
High rate of electrolyte movement in tool work piece gap washes metal ions away from the work piece ( ANODE)
This is washed just before they have a chance to plate on the tool ( cathode)
Shaped tool made of brass , copper , bronze , or stainless steel
Electrolyte is pumped at a high rate through the passages in the tool
Machines having current capacities as high as 40,000 A and as low as 5A are available

3. Parts made by Electrochemical Machining
FIGURE : Typical parts made by electrochemical machining. (a) Turbine blade made of a nickel alloy, 360 HB. Source: Metal Handbook, 9th ed., Vol. 3, Materials Park, OH: ASM International, 1980, p (b) Thin slots on a 4340-steel roller-bearing cage. (c) Integral airfoils on a compressor disk.

4. Process capabilities
Used to machine complex cavities in high strength material
Applications in aerospace industry,jet engines parts and nozzles
ECM process gives a burr free surface
No thermal damage
Lack of tool forces prevents distortion of the part
No tool wear
Capable of producing complex shapes and hard materials

5. Electrical-Discharge Machining
FIGURE Schematic illustration of the electrical-discharge-machining process.

6. Examples of EDM
FIGURE (a) Examples of cavities produced by the electrical-discharge-machining process, using shaped electrodes. The two round parts (rear) are the set of dies for extruding the aluminum piece shown in front. Source: Courtesy of AGIE USA Ltd. (b) A spiral cavity produced by a rotating electrode. Source: American Machinist. (c) Holes in a fuel-injection nozzle made by electrical-discharge machining. Material: Heat-treated steel.

7. Stepped Cavities
FIGURE Stepped cavities produced with a square electrode by EDM. The workpiece moves in the two principal horizontal directions, and its motion is synchronized with the downward movement of the electrode to produce various cavities. Also shown is a round electrode capable of producing round or eliptical cavities. Source: Courtesy of AGIE USA Ltd.

8. WIRE EDM
FIGURE : Schematic illustration of the wire EDM process. As much as 50 hours of machining can be performed with one reel of wire, which is then discarded.