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What is Electrochemical Machining?

Paul Scott
Paul Scott

Electrochemical machining (ECM) is a metal machining process involving the removal of material from a workpiece by means of electrochemical erosion. This process is achieved by passing a high current electrical charge from the positively charged workpiece through an electrolyte solution to the negatively charged “cutting tool.” This causes molecules from the workpiece to dislodge into the electrolyte in a profile that mimics the shape of the cutting tool. In this fashion, a “cut” is made in the workpiece of the same shape as the cutting tool. Although limited to use on electrically conductive materials, electrochemical machining offers several benefits including the cutting of complex internal profiles and minimal stress transfer to the workpiece.

Potential uses of electrochemical machining were already the subject of interest and experimentation as far back as the 1930s and have been a commercial reality since 1959. The principle which underpins the process is the same as electrolysis for electroplating. In ECM applications, however, the process is reversed; material is removed from and not deposited onto the workpiece. This is achieved by placing a specially shaped cathode in close proximity to, but not touching, the workpiece. A pressurized electrolyte solution is pumped between the two and acts as a conductor for a high current charge which passes from the workpiece to the cathode.

Man with a drill
Man with a drill

This current flow causes the workpiece to erode at a molecular level to form a cut which follows the shape of the cathode. This means that the cathode effectively becomes the process cutting tool. The material that dislodges from the workpiece is carried away with the electrolyte, thereby subjecting the cutting tool to very little wear during machining. The gap between the work piece and cutting tool during machining is maintained at between 0.003 and 0.03 inches (0.08 mm and 0.8 mm).

This lack of physical contact between the cutting tool and workpiece is one of the electrochemical machining method's greatest advantages because no stress or heat is transferred to the workpiece during machining. It is also possible to machine very hard materials without the related costs of expensive, ultra hard tools. Electrochemical machining is thus an appropriate way to produce very hard, precision parts such as turbine blades. A wide range of complex profiles, both internal and external, may also be machined using the procedure. The only real disadvantages of ECM techniques are the high initial installation costs and the corrosion risk to tools and workpieces posed by the electrolyte solution.

Discussion Comments


ECM process is known as reverse process of electroplating.When electrolytic circuit is same to both, how the material produced during the machining not deposited on the cathode? Though the smaller gap between anode and cathode is the reason for the above, how is the process reversed?


I would like to know what impact the temperature of slurry has on the MRR in electro chemical machining?


@miriam98 - Yes, but what you’ve described is the etching away of a very light metal coating. I think it’s called PCB board. With chemical milling, however, it’s possible to etch or drill into very hard metals.

It’s a more powerful process because it doesn’t just involve etching solution, but it uses current as well. You might be able to demonstrate a crude example of this by running battery operated terminals in a current of water and watch it begin to eat away at a small penny. The process will be slow but I think it’s the same idea.


This type of precision machining reminds me of etching, which I used to do when I was an electronics hobbyist. I would take specially coated boards and “draw” my circuit design onto the board with a special etching pen.

Then I dip the board into an etching solution and it etches away the coating, leaving only the lines where I drew my circuit design. In a matter of minutes I now have a circuit without any wiring whatsoever.

I just plug the components at appropriate points in the circuit board. I realize this is not exactly the same process but it is similar in that it’s an electrochemical process.

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