This document discusses three electrochemical techniques: electrochemical forming, electrochemical machining (ECM), and electrochemical etching. Electrochemical forming involves depositing metal particles from an electrolytic solution onto a conductive surface to form parts. ECM removes material from a workpiece using an electrochemical process where the workpiece acts as an anode and tool as a cathode in an electrolyte. Electrochemical etching permanently marks conductive metal surfaces using either conventional chemical etching, electrolytic etching, or potentiostatic etching. The techniques produce high purity materials, enable complex shapes to be formed, and result in mirror finishes. However, they can also involve long processing times, non-uniform thickness, high costs,

1. PVP SIDDHARTHA INSTITUTE OF TECHNOLOGY
(AUTONOMOUS)
KANURU, VIJAYAWADA
UNIT-IV

2. ELELCTRO CHEMICAL REACTION, Any process either caused or accompanied
by the passage of an electric current and in involving in most cases the transfer of
electrons between two substances- one a solid and the other a liquid.
ELCTRO CHEMICAL TECHNIQUES : 1.Electro Chemical Forming
2.Electro Chemical Machining
3. Electro Chemical Etching

3. Electro Chemical Forming :
Electro forming is a metal forming process that forms parts through electro deposition on a
model ( mandrel).
Principle: Metal particles are dissolved in an electroplating solution and electro chemically
depositing them on to a conductive surface.
Process: The moulds are placed in the electrolytic solution and proper current is passed in
the solution. The mould keeps on receiving the metallic ions from the metallic rod and finally
a layer of sufficient thickness is formed around the mould. It is then takeout from the bath,
rinsed and then removed from the mould.
The various metals used for electroforming include copper, nickel, iron , silver, zinc lead, tin ,
cadmium, gold , aluminum and others having conducting nature
Advantages:
* High material purity.
* Variety of shapes and dimensions is possible.
Disadvantages:
* non-uniform thickness distribution.
* Processing takes long time.
Applications:
* Production of CD’s and DVD’s.
* Ni Electro forming is in the creation of molds used to produce body and interior
components for automotive and aerospace applications.

4. Electro Chemical Machining :
ECM is a machining process in which electrochemical process is used to remove materials
from the work piece.
Process: Work piece is taken as anode and tool is taken as cathode. The 2 electrodes work
piece and tool is immersed in an electrolyte (Nacl).When the voltage is applied across the two
electrodes, the material removal from the work piece starts. The work piece and tool is
placed very closed to each other without touching. In ECM the material removal takes place
at atomic level so it produces a mirror finish surface.
Advantages:
• Complex and concave parts can be produced.
• Less heat is generated.
• Excellent surface finish is produced.
Disadvantages:
• The risk of corrosion for tool , work piece and equipment increases in the case of saline
and acidic electrolyte.
• High power consumption.
• High initial investment cost .
Applications:
• Drilling operations, press and glass making moulds.
• Manufacture of turbine and compressor blades for gas turbine engines.
• Reducing the wall thickness of shaped parts.

5. ELECTRO CHEMICAL ETCHINING :
ECE is a permanent process for high resolution part marking onto conductive metal surfaces for identification
and traceability of metal components.
Three types of etchings are
1. conventional chemical etching, 2. electrolytic or anodic etching, 3. potentiostatic etching
1.Conventional chemical etching : It is the oldest and most commonly used technique. The etchant reacts
with specimen surface without the use of external circuit supply.
2. Electrolytic or anodic etching : electrode potential is applied to specimen by means of an external circuit. It
consists anode , cathode and electrolyte.
3.Potentiostatic etching : it is an advanced form of electrolytic etching , produces etching through highly
controlled conditions.
Process: Polished PCB cut into a square. Cleaned with degreasing detergent and alcohol and air dried and
then photo resist material is applied. Then coated substrate exposed to UV exposure unit for about 30 minutes.
Finally immersed in developer solution to produce the desired PCB pattern. Conventional chemical etching of
cu is done with 40% ferric chloride solution for about 2 hours.
Advantages :
• Low cost , simple process.
• High selectivity
Disadvantages:
• Chemical contamination.
• Poor repeatability based on the influences of temperature and concentration of etchant.
Applications:
• Micro fine filters
• Carriers for silicon wafers.
• Vibration plates.
• Based for industrial diamond cutters and precision micro nozzles.