ECM : Electrochemical machining - Principle,process,subsystems & applications. Specialized processes under ECM.

1. Pratik Chaudhari
TY mech
MIS- 111210015
Subject – AMT

2. Introduction
 Non-conventional machining system in which metal is
removed by electrochemical process
 Characterized as ‘Reverse Electroplating’ means it
removes metal instead of adding it
 Normally used for mass production and for hard
materials that are difficult to machine using
conventional processes
 Both external and internal geometries can be
machined

3. Principle
 Faraday’s law of electrolysis :
The Weight of the substance produced during
electrolysis process is directly proportional to
1. the current which passes
2.the length of time of process
3.The equivalent weight of the material
 Two dissimilar metals are in contact with an electrolyte
and anode loses metal to cathode

4. •Anode : Workpiece
•Cathode : Tool
•Electrolyte : An electrically conductive fluid

5. Process parameters

6. Process

7. Main subsytem
 Power Supply
 Electrolyte
 Tool
 The Control system
 The machine

8. Power Supply
 Available in sizes upto 10,000 amp (some circuits are
available upto 40,000amp)
 Range of voltage – 2 to 30 volts d.c.
 A constant voltage has to be maintained and high
density is required

10. Electrolyte
 Essential for electrolytic process
 It cools the cutting zone which becomes hot due to the
flow of high current
 Neutral salts are used as electrolyte in place of highly
corrosive acids and alkalies
 Electrolyte solution is pumped between the
tool/workpiece gap at about 2.5 N/mm2 and 30 m/s

11. Tool
 Requirements of Tool For ECM :
 Good thermal conductivity
 Strong enough to withstand high pressures
 It should be easily machined
•Material for tool : Copper,brass or stainless steel
•Outer insulation material : Vinyl, Teflon, epoxy,
enables or high temperature varnish

12. The control system
 Control Parameters include
 Voltage
 Inlet and outlet pressure of electrolyte
 Temperature of electrolyte
•The current is dependent on above parameters
and feed rate

14. Specialized ECM…

15. STEM
Figure The shaped-tube electrolytic
machining (STEM) cell process is a
specialized ECM technique for drilling
small holes using a metal tube electrode
or metal tube electrode with dielectric
coating.

16. Electrochemical Micro-machining
•Improves resolution
of anodic dissolution
from millimetres to
micrometres
•Micromachining
applies pulses in
nanoseconds instead
of direct currents

17. Ref – L.cagnon,V.lircher,M.cock,R.schuster,G.Ertlth.Gmelin and H.kueck,
Z. Phys chem . 217, (2003), 299-313

19. Further specialized Applications
 Die Sinking
 Profiling and contouring
 Trepanning
 Grinding
 Drilling
 Micro-machining
 Pulsed ECM

22. Economics & Products
 The process is economical when a large no. of complex
identical products are to be made
 Large cavities are more economical on ECM and can be
made in 1/10th time in EDM
 Two most common products :
 Turbine/compressor blades
 Rifle barrels
Important characteristics that can be achieved are :
•Stress free grooves
•Any groove geometry
•Any conductive metal can be
machined
•Repeatable accuracy of 0.0005”
•High surface finish
•Fast cycle time

23.  ECM is well suited for the
machining of complex
two-dimensional shapes
 Delicate parts may be
made
 Difficult-to machine
geometries
 Poorly machinable
materials may be
processed
 Little or no tool wear
 Initial tooling can be
timely and costly
 Environmentally
harmful by-products
 Complicated tool
design
 Large power
consumption
Advantages
Disadvantages

24. References
 Electrochemical machining – nptel
 Science Direct – ECM
 Wikipedia – electrochemical machining
 Wendt – electrochemical machining & miccromaching

25. Thank You …