Electrochemical Machining (ECM) / Definition, parts, working, advantages, disadvantages of Electrochemical Machining (ECM)

Introduction:

Electrochemical machining is an electro-chemical based non-conventional machining process in which metals are removed by electrochemical dissolution. This process is the opposite of the electroplating process. 

Electrochemical machining works on Faraday's law of electrolysis. 

The tool is connected with the negative terminal (as the cathode) of the battery, and the workpiece is connected with the positive terminal (as the anode) of the battery. 

Both are kept at a distance in an electrolyte solution. 

 

When DC current (3 to 30V) is supplied to the electrode, the metal begins to move away from the workpiece.

See in figure electrochemical machining process and their working procedure described below in detail.

Working Procedure of Electrochemical Machining (ECM):

1. In ECM, NaCI is usually in water as an electrolyte. 
2. The tool is connected to the negative terminal, and the workpiece is connected to the positive terminal. 
3. When current passes through the electrodes, the anode or workpiece and the cathode or tool reaction occurred >
4. NaCI = (Na+)  +  (CI-) 
5. H20 =( H +)  + ( OH-)
6. Positive ions move towards the tool and negative ions towards the workpiece. 
7. Thus the hydrogen ion moves towards the tool.  
8. As hydrogen reaches the tool, it takes some electrons from it and turns into a gas. This gas goes into the environment.

Application of Electrochemical Machining (ECM):

1. ECM is used in the machining of disc or turbine rotor blades. 
2. It can be used to slot very thin walled collets. 
3. The ECM is used to generate the internal profile of the internal cam. 
4. ECM is also used in the Production of satellite rings and connecting rods, machining of gears and long profiles, etc.

Advantages of Electrochemical Machining (ECM):

1. It can machine very complex surfaces. 
2. A single tool can be used for machining a large number of workpieces.
3. Metal machining does not depend on the strength of the tool and the hardness of the tool. 
4. ECM provides a very high surface area.

Disadvantages of Electrochemical Machining (ECM) :

1. High initial cost of the machine. 
2. The design and tooling system is complex. 
3. The fatigue property of the machined surface may be reduced.  
4. Nonconducive materials cannot be machined. 
5. Blind holes cannot be machined through ECM.

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