ELECTRO-CHEMICAL MACHINING (ECM)

ECM Electro-chemical Machining

ECM is a process in which "the controlled removal of metal by anodic dissolution of the workpiece in an electrolytic cell where the workpiece acts as anode and tool acts as cathode".

Working :-

1. ECM process is based on Faraday's Laws of electrolysis, where workpiece acts as anode and tools acts as cathode.
2. The tool and workpiece are held close to each other with a small gap (upto 0.5 mm) between them.
3. A D.C. Voltage of about 3-30 V is applied between the tool and workpiece, and electrolyte is pumped into the gap.
4. Due to this flow of ions, electrochemical reaction takes place and hence there is removal of metal from the workpiece in the form of sludge.
5. This sludge is taken away from the gap by the electrolyte which is flowing continuously.

Advantages of ECM :-

1. Materials which are good conductor of electricity can be easily machined with no effect on mechanical properties of material.
2. Complicated shapes can be easily machined.
3. MRR is high as compared to other processes.
4. As there is contact between workpiece and tool, then also took wear is almost negligible.
5. The machined surface is stress free.

Disadvantages of ECM :-

1. Only electrically conductive materials can be machined.
2. Due to continuous supply of electrolyte in the process, there is corrosion and rusting of workpiece, tool and used fixture.
3. Fine radius can not be generated.
4. More floor space is required.
5. Initial cost of equipment and tool is quite high.

Applications of ECM :-

1. It is mainly used for hard and heat resistant materials.
2. For producing blind holes, a pocket in forging dies ECM is preferred.
3. Small deep holes, such as in nozzles can be drilled.
4. Deburring of parts can be done.