Detailed explanation of Electro Chemical Machining

1. Electro Chemical Machining
LOCHAN KAMPALI 1AT16ME037
MOHD.IBRAHIM JUNAID 1AT16ME045
SUMAN K 1AT16ME091
HARSHITH P 1AT16ME119
ABIJEET K P S 1AT17ME001
Atria Institute Of Technology
Anand Nagar Bangalore
Department Of Mechanical Engineering
Course Coordinator
Mr Anjan Kumar
Assistant Professor
Course - Non Traditional Machining

2. Definition
Electrochemical machining is a method of removing metal by an
electrochemical process.
It is normally used for mass production and is used for working
extremely hard materials or materials that are difficult to
machine using conventional methods.

3. Working Principle
• The Electro Chemical Machining works on the principle of Faraday’s law of
electrolysis.
• Faraday’s first law of electrolysis- “The mass of a substance altered at an
electrode during electrolysis is directly proportional to the quantity of
electricity transferred at that electrode. Quantity of electricity refers to the
quantity of electrical charge, typically measured in Coulomb.”
• Faraday’s second law of electrolysis- “For a given quantity of DC electricity,
the mass of an elemental material altered at an electrode is directly
proportional to the element’s equivalent weight. The equivalent weight of a
substance is equal to its molar mass divided by the change in oxidation state it
undergoes upon electrolysis.

4. In electrochemical machining, the workpiece forms the anode, and a properly
insulated tool having shape similar to that desired in the workpiece forms the
cathode part of the electric circuit. The tool and the workpiece are positioned
closer to each other with a conductive electrolyte flowing through a small gap
between the workpiece and tool. When the current is passed, dissolution of the
workpiece(anode) occurs. The chemical properties of the electrolyte are such
that, the constituents of the workpiece material(anode)
Dissolve into the solution during electrolysis, but do not plate on the
tool(cathode). The shape obtained in workpiece material is exactly similar to the
shaped tool.

5. Schematic Setup Of Machine
In operation, the tool having a shape, similar to that desired in the
workpiece is fed towards the workpiece maintaining a small gap between
them. This is accomplished by utilizing a servo-drive on the negative
terminal (cathode) and the workpiece to the positive terminal(anode). The
electrolyte is pumped at a high pressure through the small gap between
the tool and the workpiece, thus providing the necessary path for
electrolysis . When the current is passed, dissolution of the
workpiece(anode) occurs. Meanwhile the flowing electrolyte washes the
metal ions away from the workpiece before they have a chance to plate
onto the tool. As the tool moves downwards to maintain a constant gap,
the workpiece is machined to the same shape as that of a tool.

7. List of equipment and its functions
•Tool
•Electrolyte
•Filters
•Source for power supply

8. Tool
• Tool is used to get the desired shape on the workpiece.
Electrolyte
• In electrochemical machining, the electrolyte performs the following functions:
• Complete the electric circuit between the tool and the workpiece.
• Act as a conductor to carry current.
• Remove the products of electrochemical reaction from the gap between the tool-work interface.
• Carry the heat generated from the machining zone.
Filters
• Filters are placed in the system to clean the contaminated electrolyte, so that a fresh flow of
electrolyte to the machining area takes place at all times.
Power supply
• The AC power available from the mains is converted to low voltage DC by a step-down transformer
and a rectifier.
• The power supply also includes a protective device for switching OFF in the event of the tool getting
too close to the workpiece, or failure of electrolyte supply, or supply of improperly filtered
electrolyte.

9. Process Parameters
• Current density
• Tool feed rate
• Velocity of electrolyte flow
• Gap between workpiece and tool

10. Current density
• Current density is simply the current that can be passed into a square inch of work area.
• At low current densities, metal removal rate is small.
• The electrochemical machine used for a particular application must have sufficient current
available to maintain a current density of 50-1500 A/in^2.
Tool feed rate
• The tool feed rate is directly proportional to current density.
• If the feed rate is increased, the electrical resistance of the
tool-work gap reduces to allow more current to flow
resulting in high metal removal rates.
• Also surface finish and accuracy is improved.
Gap between workpiece and tool
• The tool and the workpiece are positioned as close together to encourage efficient electrical
transmission Small gap results in high current densities and hence, more metal removal rate. It is
important to maintain a uniform gap between the tool and the workpiece Any physical contact of
the tool and the workpiece results in arcing and serious damage to both the members.
Velocity of electrolyte flow
Electrolyte flow may be between 15-60 m/s. If electrolyte flow is too low, the heat and by-products of
the electrolytic reaction (hydrogen gas bubbles, sludge etc.) build in the gap causing non-uniform metal
removal. Too high velocity will cause cavitation, also promoting non-uniform metal removal.

11. Advantages Of ECM
• Accurate shape with good surface finish can be obtained.
• Machined surface is stress-free and has high surface finish.
• No physical contact between the tool and the workpiece. Hence, no tool wear,
and also no burrs are produced.
• Capable of machining metals and alloys irrespective of their strength and
hardness.
• Metal removal is due to anodic (workpiece) dissolution. Hence, no thermal
effects on the workpiece.
• Process can be easily automated.
• Several tools could be connected to a cassette to make many cavities
simultaneously.
• Suitable for mass production applications.

12. Limitations Of ECM
• Suitable only for conductive materials.
• Inability to machine sharp interior edges and corners because of very high current
densities at these points.
• Space and floor requirements are higher than conventional machines.
• High electrical power is consumed.
• Post-machining and cleaning is a must to reduce the corrosion of workpiece.
• Limited to mass production because of high tooling and set-up costs.
• Not environmental friendly. The sludge produced in large amounts need to be
disposed off.
• Frequent maintenance of equipment is necessary in order to avoid corrosion of
parts.

13. Applications Of ECM
• Die-sinking operation • Drilling jet engine turbine blades

14. • Multiple hole drilling
• Micro machining
• Rifling barrel

15. References
• https://www.youtube.com/watch?v=b1nX7WVIN7U
• https://www.youtube.com/watch?v=12-IOyuPJZo
• https://www.youtube.com/watch?v=Ej-GWNPYFVM
• https://www.youtube.com/watch?v=Q1Z9DpoGW7Y
• https://www.youtube.com/watch?v=vlG-44RTdgk
• https://en.wikipedia.org/wiki/Electrochemical_machining
• https://mechanicalenotes.com/electrochemical-machining

16. THANK YOU