iaetsd electrochemical machining of

ELECTROCHEMICAL MACHINING OF

SS 202

Bharanidharan1,Jhonprabhu

2

Department of Mechanical Engineering

M.Kumarasamy college of Engineering, Karur -639 113

Email: [email protected], [email protected]

ABSTRACT

The aim of this project is to study

the material removal rate in an

electrochemical machining process

of SS 202 material. When the

electrodes are immerged in the

electrolyte the electrons are

removed from the anode and

deposited in the electrolytic tank.

After taken the first reading the

electrode immerged in the

electrolyte again with high distance.

So the electrons are removed from

the anode for the given distance.

The electrode distance also varied.

When the immersion depth is

increased the material removal rate

Decreased and then the electrode

distance is increased the material

removal rate increased. The voltage

increased means the material

removal rate is increased. So the

material removal rate is dependent

upon the voltage immerged

distance.

Results indicated that material

removal rate is dependent on three

factors

1) Power supply,

2) Distance between anode and

cathode,

3) Depth of immersion.

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ISBN: 378-26-138420-01

CHAPTER-1

INTRODUCTION

IMPORTANCE OF ECM:

In electro chemical machining

process there is no residual stress

induced in the work piece. But other

machining process like lathe the

residual stress are induced. There is

no tool wear; machining is done at

low voltages compared to other

processes with high metal removal

rate; small dimensions can be

controlled; hard conductive materials

can be machined into complicated

profiles; work piece structure suffer

no thermal damages; suitable for mass

production work and low labour

requirements.

CHAPTER-2

LITERATURE REVIEW

M.H. Abdel-Aziz - May 2014:

The effect of electrode oscillation on

the rate of diffusion-controlled anodic

processes such as electro polishing

and electrochemical machining was

studied by measuring the limiting

current of the anodic dissolution of a

vertical copper cylinder in phosphoric

acid. Parameters studied were

frequency and amplitude of

oscillation, and phosphoric acid

concentration. Within the present

range of conditions, electrode

oscillation was found to enhance the

rate of anodic dissolution up to a

maximum of 7.17 depending on the

operating conditions. The mass

transfer coefficient of the dissolution

of the oscillating vertical copper

cylinder in H3PO4 was correlated to

other parameters by the equation:

Sh=0.316Sc0.33Rev0.64.The

importance of the present study for

increasing the rate of production in

electro polishing and electrochemical

machining, and other

electrometallurgical processes limited

by anode passivity due to salt

formation such as electro refining of

metals was highlighted.



ISBN: 378-26-138420-01

F. Klocke – 2013:

In order to increase the efficiency

of jet engines hard to machine

nickel-based and titanium-based

alloys are in common use for

aero engine components such as

blades and blisks (blade

integrated disks). Here

Electrochemical Machining

(ECM) is a promising alternative

to milling operations. Due to lack

of appropriate process modeling

capabilities beforehand still

knowledge based and a cost

intensive cathode design process

is passed through.

Therefore this paper presents a

multi-physical approach for

modeling the ECM material

removal process by coupling all

relevant conservation equations.

The resulting simulation model is

validated by the example of a

compressor blade. Finally a new

approach for an inverted cathode

design process is introduced and

discussed.

M. Burger - January 2012:

Nickel-base single-crystalline

materials such as LEK94 possess

excellent thermo-mechanical

properties at high temperatures

combined with low density compared

to similar single-crystalline materials

used in aero engines. Since the

components of aero engines have to

fulfill demanding safety standards, the

machining of the material used for

these components must result in a

high geometrical accuracy in addition

to a high surface quality. These

requirements can be achieved by

electrochemical and precise

electrochemical machining

(ECM/PECM). In order to identify

proper machining parameters for

PECM the electrochemical



ISBN: 378-26-138420-01

characteristics dependent on the

microstructure and the chemical

homogeneity of LEK94 are

investigated in this contribution. The

current density was found to be the

major machining parameter affecting

the surface quality of LEK94. It

depends on the size of the machining-

gap, the applied voltage and the

electrical conductivity of the

electrolyte used. Low current

densities yield inhomogeneous

electrochemical dissolution of

different micro structural areas of the

material and lead to rough surfaces.

High surface qualities can be achieved

by employing homogenous

electrochemical dissolution, which

can be undertaken by high current

densities. Furthermore, a special

electrode was developed for the

improvement of the quality of side-

gap machined surfaces.

CHAPTER-3

ELECTROCHEMICAL

MACHINING PROCESS:

fig.3.1

In ECM, the principles of electrolysis

are used to remove metal from the

work pieces. FARADAY’S LAWS of

electrolysis may be stated as: “the

weight of substance produced during

electrolysis is directly proportional to

the current which passes the length of

time of the electrolysis process and

the equivalent weight of the material,

which is deposited”. The work piece

is made the anode and the tool is

made the cathode. The electrolyte is



ISBN: 378-26-138420-01

filled in the beaker. As the power

supply is switched on and the current

flows through the circuit, electrons

are removed from the surface atoms

of work piece. These can get

deposited in the electrolytic tank.

After applying current the electron

will move towards the work piece

and also the settles down in the

bottom. The tool is fed towards the

work piece automatically at constant

velocity to control the gap between

the electrodes the tool face has the

reverse shape of the desired work

piece. The sides of the tool are

insulated to concentrate the metal

removal action

at the bottom face of the tool. The

dissolved metal is carried away in the

flowing electrolyte. The positive

supply is supplied to Stainless Steel

202 material.

3.1 Experimental setup:

fig.3.1A

COMPONENTS:

Power supply

Work piece

Tool

Electrolyte and Electrolytic tank

3.2 POWER SUPPLY:

The range of voltage on

machine 240 volts A.C. In the ECM

method a constant voltage has to be

maintained. At high current densities,

the metal removal rate is high and at

low current densities, the metal

removal rate is low. In order to have a

metal removal of the anode a

sufficient amount of current has to be

given. The Power supply is one of the



ISBN: 378-26-138420-01

main sources in our project. Because

of the material removal rate is

calculated depends on amount of

power supplied to the work piece.

3.3WORKPIECE:

The work piece is stainless

steel 202.it is a general purpose

stainless steel. Decreasing nickel

content and increasing manganese

results in weak corrosion resistance.

fig.3.2

Length of the ss 202 = 35.7cm

Diameter of the ss202 = 0.8cm

PROPERTIES:

SS202 Material is

selected as anode based on

different properties.

PHYSICAL PROPERTIES:

PROPERTY

VALUE

Density 7.80 g /

cm3

Thermal

expansion

17× 10-6

/

k

Modulus of

Elasticity

200

GPa

Thermal

Conductivity

15 W /

mk

MECHANICAL

PROPERTIES:

PROPERTY

VALUE

Proof Stress 310

MPa

Tensile Strength 655

MPa

Elongation 40 %



ISBN: 378-26-138420-01

3.4 Tool:

The tool is iron. At increasing the

carbon content of the iron will

increase the tensile strength and iron

hardness. The iron is suitable for

cathode and easily reacts with anode.

Length of the iron = 15cm

Diameter of the iron = 1cm

fig.

Low pressure Phase diagram of iron

fig.3.3

3.5 Electrolyte:

The electrolyte is hydrochloric acid.

Boiling, melting point, density and ph

depends on the concentration. It is a

colourless and transparent liquid,

highly corrosive, strong mineral acid.

HCL is found naturally in gastric acid.

The HCL is highly concentrated. In

that process amount of HCL is 550ml.

fig.3.4

3.6 Electrolytic tank:

Length of the tank = 20 cm

Height of the tank = 12.5 cm



ISBN: 378-26-138420-01

3. EXPERIMENTAL

ELECTROCHEMICAL

MACHINING

CALCULATION FOR

CONSTANT POWER

SUPPLY

3.1. TABULATION 1:

The material removal rate is

calculated by immerging distance of

anode and cathode. 240 V current

supply is input for the anode and

cathode. The supply 240 V current is

constant. The MRR is calculated after

15 minutes by using the formulas.

S.NO VOLTAGE

(Volts)

TIME

(Min)

ELECTRODE

DISTANCE

(cm)

MATERIAL

REMOVAL

RATE(cm3

min-1

)

1. 240 15 12 1.191

2. 240 15 8 1.186

3. 240 15 6 1.157

Table.2


calculated by electrode distance of

anode and cathode. 240 V current

supply is input for the anode and

cathode. The supply 240 V current is

constant. The MRR is calculated after

15 minutes by using the formulas.

3.2. FORMULAE USED:

MATERIAL REMOVAL

RATE:

It is a ratio between volume of work

piece to time taken for the material

removal.

MRR = (VOLUME OF WORK

PIECE) / (TIME TAKEN)

UNIT: cm3 /min

S.NO VOLT

AGE

(Volts)

TIM

E

(Min)

IMMER

GEDDIS

TANCE

(cm)

MATER

IAL

REMO

VALRA

TE(cm3

min-1

)

1. 240 15 2.8 1.191

2. 240 15 3.1 1.186

3. 240 15 6.5 1.157



ISBN: 378-26-138420-01

Volume of work piece:

V = πr2h

r - Radius of the work piece, h -

Length of the work piece

3.3. Calculation:

Volume of removed material, V= πr2h

V = π× (0.39)2×2.8

V = 0.4778×2.8

V =1.34 cm3

Volume of remaining

Material, V= πr2h

V= π× (0.4)2×32.9

V= 0.5026× 32.9

V= 16.53 cm3

Total volume = Volume of removed

material + Volume of remaining

material = 1.34 + 16.53

= 17.87 cm3

MRR = (VOLUME OF WORK

PIECE) / (TIME TAKEN)

MRR= 17.87 / 15

MRR= 1.1913 cm3/min

3.4. RESULT:

Fig 10 & 11

When the immerged distance is


decreased

When the electrode distance is


increased.

4. EXPERIMENTAL

ELECTROCHEMICAL

MACHINING

CALCULATION FOR

VARIABLE POWER

SUPPLY:

01020

MRR VS ELECTRODE DISTANCE

MRR VS ELECTRODE DIST…

1.1

1.15

1.2

2.8 3.1 6.5

IMMERGED DISTANCE VS …

IMMERGED DISTANCE VS …



ISBN: 378-26-138420-01


calculated by varying the power

supply. The material removal rate is

calculated up to 30V. The power

should be varied every 10 V supply.

COMPONENTS:

RPS meter

Power supply

Work piece

Tool

Electrolyte

Electrolytic tank

4.1. RPS METER:

RPS is stand for Regulator Power

Supply. The function of the meter is

varying the power supply. The range

of meter is 0-30V.

In this tabulation the voltage is varied

from 0-30V. At the same time the

immerged distance (2.8cm) and time

(45min) will be constant. The voltage

is increase means the material

removal rate also increased.

S.N

O

VOLTA

GE

(volts)

TIM

E

(min

)

IMMERG

ED

DISTANC

E

(cm)

MATERI

AL

REMOV

AL

RATE(cm3

min-1

)

1. 10 45 3.1 0.118

2. 20 45 3.1 0.156

3. 30 45 3.1 0.194

S.N

O

VOLT

AGE

(volts)

TI

ME

(mi

n)

IMMER

GED

DISTAN

CE

(cm)

MATE

RIAL

REMO

VAL

RATE(c

m3

min-

1)

1. 10 45 2.8 0.129

2. 20 45 2.8 0.167

3. 30 45 2.8 0.216



ISBN: 378-26-138420-01

In this tabulation the voltage is varied

from 0-30V. At the same time the

immerged distance (3.1cm) and time

(45min) will be constant.

RESULT:

Fig 13 & 14

The applied voltage is increased

means the material removal rate also

inceased. In the first graph the

workpiece immerged distance is 2.8

cm and the second graph the

workpiece immerged distance is 3.1

cm. In these two graphs material

removal rate value is taken in X-axis

and current voltage is taken in Y-

axis. So the graph between material

removal rate vs votage.

5. CONCLUSION:

When the immerged distance is


decreased and then the electrode

distance is increased the material

removal rate increased. The voltage

increased means the material removal

rate is increased. So the material

removal rate is dependent upon the

voltage immerged distance.

6. APPLICATION:

Some of the very basic applications of

ECM include:

1. Die-sinking operations.

2. Drilling jet engine turbine blades.

3. Multiple hole drilling.

4. Machining steam turbine blades

within close limits.

0

5

10

15

20

25

30

35

0.118 0.156 0.194

MRR VS VOLTAGE

MRR VS VOLTAGE

0

10

20

30

40

0.129 0.167 0.216

MRR VS VOLTAGE

MRR VS VOLTAGE



ISBN: 378-26-138420-01

7. REFERENCE:

1. Journal of the Taiwan Institute of

Chemical Engineers, Volume 45,

Issue 3, May2014, Pages840-845

M.H. Abdel-Aziz, I. Nirdosh, G.H.

Sedahmed.

2. ProcediaCIRP, Volume8, 2013,

Pages265-270 F. Klocke, M. Zeis, S.

Harst, A. Klink, D. Veselovac, M.

Baumgärtner.

3. journal of Manufacturing

Processes, Volume 14, Issue 1,

January 2012, Pages62-70 M. Burger,

L. Koll, E.A. Werner, A. Platz.

4. Manufacturing Process Selection

Handbook, 2013, Pages 205-226

K.G. Swift, J.D. Bookers

8. EXPRIMENT PICTURES:



ISBN: 378-26-138420-01



ISBN: 378-26-138420-01