This document discusses parameters that affect the surface roughness of electrochemically machined surfaces. It outlines several key parameters including: the type of power supply used, duty cycle, voltage, inter-electrode gap, electrolyte concentration, temperature and flow rate, the type of tool used, and the micro-tool feed rate. Maintaining an optimal inter-electrode gap of 15-20 micrometers and using a duty cycle of 0.3 were found to produce the best surface roughness. The concentration of the electrolyte and keeping the temperature below 50 degrees Celsius also impacted surface quality.

1. NITK SURATHKAL
Submitted By:
Veerendra chaurasiya
Roll no. 172DP160
Study on the parameters affecting the surface
roughness of electro-chemical machined surface
Submitted To:
Dr. Prasad Krishna
Department of mechanical engineering
Presentation
on

2. Used in Russia Ref.[7]

3. Introduction
 ECM: anodic dissolution process
 workpiece and tool are respectively anode
and cathode,
 Separated by electrolyte.
 Gap between anode and cathode: IEG (inter
electrode gap)
 ECM is often characterized as "reverse
electroplating," in that it removes material
instead of adding it.

4. ECM:
The anode workpiece dissolves locally so that the shape generated
is approximately negative mirror image of tool.

5. ECM:
Plays an important role in manufacturing of a variety
of parts ranging from machining of complicated shape,
complex, and large metallic pieces.

6. Elements of ECM
Important elements of ECM are:
1. Electrolyte
2. Tool (cathode)
3. Work-piece (anode)
4. D.C power supply
5. Pump

7. Fig. schematic of electrochemical machining setup

8. Electrolytic dissolution of iron.

9. Continue..
• Ions which carry positive charges move through the electrolyte in the
direction of the positive current, that is, toward the cathode, and are called cat
anions.
• The negatively charged ions travel toward the anode and are called anions.
•
• The movement of the ions is accompanied by the flow of electrons, in the
opposite sense to the positive current in the electrolyte.
• Both reactions are a consequence of the applied potential difference, that is,
voltage, from the electric source.

10. Working Principle

11. Continue..
•the workpiece and tool are the anode and cathode, respectively, of an
electrolytic cell, and a constant potential difference, usually at about 10 V, is
applied across them.
• A suitable electrolyte, for example, aqueous sodium chloride (table salt)
solution, is chosen so that the cathode shape remains unchanged during
electrolysis.
•The electrolyte is also pumped at a rate 3 to 30 meter/second, through the gap
between the electrodes to remove the products of machining and to diminish
unwanted effects, such as those that arise with cathodic gas generation and
electrical heating.

12. Continue..
• The rate at which metal is then removed from the anode is approximately in
inverse proportion to the distance between the electrodes
• As machining proceeds, and with the simultaneous movement of the cathode
at a typical rate, for example, 0.02 millimeter/second toward the anode.
• the gap width along the electrode length will gradually tend to a steady-state
value. Under these conditions, a shape, roughly complementary to that of the
cathode, will be reproduced on the anode.

13. Chemical reactions
as potential difference is applied
NaCl ↔ Na+ + Cl-
H2O ↔ H+ + (OH) –
at anode
Fe = Fe++ + 2e-
at cathode
2H+ + 2e- = H2↑
Within the electrolyte
Na+ + OH- = NaOH
Fe+++2OH- = Fe(OH)2
Fe+++2Cl- = FeCl2
In practice FeCl2 and Fe(OH)2

14. Material removal rate
m ∝ Q,
where m = mass of material dissolved or deposited
Q = amount of charge passed
m α ECE α
𝐴
ν
Thus m α
QA
ν
Where
ECEE= electrochemical Equivalence of the material
A= atomic weigh and
V= valency.
where F = Faraday’s constant
= 96500 coulombs
Where I = current
ρ= density of the material

15. Affecting parameters of electro chemical machined
surface
1. Nature of power supply
2. duty cycle
3. voltage
4. Inter electrode gap
5. Concentration, temperature and flow rate of electrolyte
6. Tools
7. Micro-tool feed
REF.[7]

17. 1.Nature of power supply
• Type: direct current
• Voltage: 2 to 35 V
• Current: 50 to 40,000 A
• Current density: 20 A/cm2 to 300 A/cm
• Metal removal rate directly proportional to
current
• Electrolyte temperature increase

18. 2.Duty cycle
• At a duty cycle of 0.3, the surface has its best surface roughness
• Under the condition of a low duty cycle, the processing time is very low, there is
enough time for removal of the electrolytic product.
• At higher duty cycle processing time increases.

19. 3.Effect of voltage
• surface roughness becomes worse with increasing voltage.
• the surface roughness is better when the voltage rises above 30 V.
• the surface roughness improves as the voltage increases in the range of 30–
40 V.

20. 4.Inter electrode gap
• Maintaining IEG 15to20μm uniformly >>> to achieve high accuracy
and surface finish.
• Metal removal rate is inversely proportional .

21. 5.Concentration, temperature and flow rate of
electrolyte
1.concentration
• A concentrated electrolyte offers low resistance to flow of machining current.
• Metal may be removes beyond the limited.
• The disadvantage is that salts crystallize out of the solution at higher
concentration and clog the are as in the machine enclosure

22. 2.Temperature
• The surface roughness becomes poorer with increasing temperature.
• Electrolyte temperature is higher than 50 °C, the quality of the surface
deteriorates.
• Rise in temperature of electrolyte tends to decrease its specific resistance.
• These changes would flow rate/pressure characteristics of the electrolyte.
• Metallurgical property changed due to high temperature.
• Workpiece material no longer dissolves uniformly.

23. 3.Flow of electrolyte
• Nontoxic electrolyte should be used
• electrolyte is pumped from a storage tank via a pressure controller
• delivery systems and multi nozzle systems.
Variations of electrolyte condition along the machining
length
REF. [3]

24. 6.Tools
• Tool in ECM are high electrical and thermal
conductivity, corrosion resistance and rigidity to
withstand the electrolytic flow.
• Low frequency tool vibrations were found to
improve machining rate and accuracy
• The effects of tool geometry, electrolyte immersion
depth, size and length on the machining rate,
accuracy and gap size.

25. 7.Micro-tool feed
• Inter Electrode Gap always tries to increase due to removal of metal from
workpiece.
• the process always tries to attain the equilibrium gap.
• MRR to avoid short circuit during machining, since short circuit can severely
damage both the micro tool and delicate surface of the workpiece.

26. REF.[4]

27. • Conclusion
• with a better surface finish being achieved at frequencies above 400 Hz.
• The optimized parameters for ECM are NaCl concentration 13wt%
• voltage 20 V, frequency 0.4 kHz, duty cycle 0.3, temperature 23 ˚C, and
• feed rate 0.5 mm/min, and the best surface roughness obtained is 0.912
lm.

28. [References]
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assisted machining of inconel 718 using Nd: YAG laser source." Journal of
Advanced Research 8.4 (2017): 407-423
ii. Burger, M., et al. "Electrochemical machining characteristics and resulting surface
quality of the nickel-base single-crystalline material LEK94." Journal of
Manufacturing Processes 14.1 (2012): 62-70.
iii. Deconinck, D., et al. "Study of the effects of heat removal on the copying accuracy
of the electrochemical machining process." Electrochimica Acta 56.16 (2011):
5642-5649
iv. Chen, Xuezhen, et al. "Experimental research on electrochemical machining of
titanium alloy Ti60 for a blisk." Chinese Journal of Aeronautics 29.1 (2016): 274-
282..

29. v. Kozak, Jerzy, and Maria Zybura-Skrabalak. "Some Problems of
Surface Roughness in Electrochemical Machining
(ECM)." Procedia CIRP 42 (2016): 101-106.
vi. Song, Xianghua, et al. "The effect of pulse frequency on the
electrochemical properties of micro arc oxidation coatings formed
on magnesium alloy." Journal of Magnesium and Alloys 1.4
(2013): 318-322.
vii. Wikipedia image.