Prepared by:

Bhavin D. Patel (090780119014)Vivek S. Patel (090780119056)

Guided by:

Prof. Nikunj.M.Patel

Parametric Analysis of material

removal rate and surface roughness

on Electric Discharge Machine

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CONTENT:-

Introduction of EDM

Working principle of EDM

Objective of EDM

Types of EDM

Application of EDM

Advantages of EDM

Limitation of EDM

Method Of Formulation

Detail description

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Experimental Set Up

Property table

Experimental table

Conclusion

Graph

Analysis of Variance(ANOVA)

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Photos

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Electro Discharge Machining (EDM) is an electro-thermal non-

traditional machining Process, where electrical energy is used

to generate electrical spark and material removal mainly occurs

due to thermal energy of the spark.

EDM is mainly used to machine difficult-to-machine materials

and high strength temperature resistant alloys. EDM can be used

to machine difficult geometries in small batches or even on job-

shop basis. Work material to be machined by EDM has to be

electrically conductive.

INTRODUCTION OF EDM

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5

Fig : Schematic of EDM process

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WORKING PRINCIPLE OF EDM

In this process the metal is removing from the work piece due to

erosion case by rapidly recurring spark discharge taking place

between the tool and work piece. mechanical set up and electrical

set up and electrical circuit for electro discharge machining.

A thin gap about 0.025mm is maintained between the tool and

work piece by a servo system

Both tool and work piece are submerged in a dielectric fluid.

Kerosene/EDM oil is very common type of liquid dielectric

although gaseous dielectrics are also used in certain cases.

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Figure : Set up of Electric discharge machining

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OBJECTIVE OF EDM

To understand of basic principle of EDM process.

To understand application of EDM die sinking machine.

To familiar with typical specification and structure of EDM die

sinking machine.

To familiar with the operation procedure.

To be able to prepare parameter setting for different application.

To be able to set the alignment of the electrode and work piece.

To be able to appreciate the quality of result product.

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9

TYPES OF EDM

Die-sinking

wire-cut

DIE-SINKING EDM

In the Sinker EDM Machining process, two metal parts submerged in an insulating

liquid are connected to a source of current which is switched on and off

automatically depending on the parameters set on the controller.

When the current is switched on, an electric tension is created between the two

metal parts. If the two parts are brought together to within a fraction of an inch the

electrical tension is discharged and a spark jumps across. Where it strikes, the

metal is heated up so much that it melts. Sinker EDM, also called cavity type EDM

or volume EDM consists of an electrode and work piece submerged in an

insulating liquid such as, more typically, oil or, less frequently, other dielectric

fluids. The electrode and work piece are connected to a suitable power supply.

The power supply generates an electrical potential between the two parts. As

the electrode approaches the work piece, dielectric breakdown occurs in the fluid,

forming a plasma channel, and a small spark jumps.

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APPLICATION OF EDM

It is used to machine extremely hard materials that are difficult

to machine like alloys, tool steels, tungsten carbides etc.

It is used for forging, extrusion, wire drawing, thread cutting.

It is used for drilling of curved holes.

It is used for internal thread cutting and helical gear cutting.

It is used for machining sharp edges and corners that cannot be

machined effectively by other machining processes

Higher Tolerance limits can be obtained in EDM machining.

Hence areas that require higher surface accuracy use the EDM

machining process.25-May-13

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ADVANTAGES OF EDM

By this process, materials of any hardness can be machined.

No burrs are left in machined surface.

One of the main advantages of this process is that thin and

fragile/brittle components can be machined without distortion.

Complex internal shapes can be machined.

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LIMITATIONS OF EDM

Material removal rate is low and the process overall is

slow compared to conventional machining processes.

Unwanted erosion and over cutting of material can occur.

Rough surface finish when at high rates of material

removal.

This process can only be employed in electrically

conductive materials.

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METHOD OF FORMULATION

We do ANOVA analysis basis of data obtain

DETAIL DESCRIPTION

Pulse On-time : The duration of time the current is allowed

to flow per cycle. Material removal is directly proportional to

the amount of energy applied during this on-time. This

energy is really controlled by the peak current and the length

of the on-time.

Discharge current : Current is measured in amp Allowed to

per cycle. Discharge current is directly proportional to the

Material removal rate.

Input parameter

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Pulse Off-time: The duration of time between the sparks This

time allows the molten material to solidify and to be wash out of

the arc gap. This parameter is to affect the speed and the stability

of the cut. Thus, if the off-time is too short, it will cause sparks to

be unstable.

Output parameter

We can do measure material removal rate (MRR)

M.R.R =Initial weight - Final weight

Density of material Machining time

In this experiment, take machining time = 5 minutes

Density of work piece material 7.84 gm/cm3

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Dielectric fluid

It acts as a coolant in quenching the sparks.It carries away the eroded metal along with it.

Kerosene & paraffin oil are generally used as

dielectric fluid

Roughness is a measure of the texture of a surface. It is

quantified by the vertical deviations of a real surface from its

ideal form. If these deviations are large, the surface is rough, if

they are small the surface is smooth. Rough surfaces usually

wear more quickly and have higher friction coefficients than

smooth surfaces.

Surface Roughness

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PHOTOS

Copper electrode

(15mm =Diameter)

(25mm =Length)

Brass electrode

(15mm =Diameter)

(25mm=Length)

Mild steel work piece

(30 30 mm)

(a)Before machining (b)After machining

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EDM Die sink machine

EXPERIMENTAL SET UP

Working current 15 to 25 amps

Power consumption 3 KW

Pulse ON/OFF Time 2 - 2000µs

Input power 415V,50HZ,3Phase,

AC

Table size 350×220mm

Table travel:(Longitudinal X axis)

(Cross Y axis)

220mm

130mm

Workpice maximum height 150mm

Workpice maximum weight 130mm

Maximum electrode weight 20Kg

Tank size (inside) 600×370×90mm

Dielectric receivers capacity 50 Ltrs

Specification :-

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Surface roughness tester

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PROPERTY TABLE

Sr.no Material properties

Ultimate

tensile

stress

(MPa)

Yield

tensile

stress

(MPa)

Poisson’s

ratio

Density

(Kg/m^3)

Thermal

conductivity

(W/m-K)

Modulus

of

elasticity

(MPa)

1 Copper 172-220 62-69 0.34 8800-

8940

391 0.117

2 Brass 338-469 124-

310

0.31 8490 115 0.097

3 Mild

steel

280-410 280 0.3 7840 47 2.0

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Sr. No Current Pulse ON Pulse OFF M.R.R S.R1 7.8125 3 3 0.008418 3.15

2 7.8125 3 5 0.007653 3.74

3 7.8125 3 7 0.003827 3.36

4 7.8125 5 3 0.010714 4.24

5 7.8125 5 5 0.008929 3.79

6 7.8125 5 7 0.005612 3.12

7 7.8125 7 3 0.010459 4.88

8 7.8125 7 5 0.010969 4.32

9 7.8125 7 7 0.008673 4.85

10 14.0625 3 3 0.022194 2.26

11 14.0625 3 5 0.014031 3.21

12 14.0625 3 7 0.005612 3.28

13 14.0625 5 3 0.021173 3.81

14 14.0625 5 5 0.015816 2.34

15 14.0625 5 7 0.009184 3.63

16 14.0625 7 3 0.019898 4.99

17 14.0625 7 5 0.020663 4.81

18 14.0625 7 7 0.017092 5.4

19 23.4375 3 3 0.030102 2.76

20 23.4375 3 5 0.034184 3.26

21 23.4375 3 7 0.030357 3.34

22 23.4375 5 3 0.038776 3.61

23 23.4375 5 5 0.037755 3.93

24 23.4375 5 7 0.033673 4.63

25 23.4375 7 3 0.040306 4.21

26 23.4375 7 5 0.041327 6.51

27 23.4375 7 7 0.039286 4.3

EX

PE

RIM

EN

TA

L T

AB

LE

FO

R

CO

PP

ER

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EX

PE

RIM

EN

TA

L T

AB

LE

FO

R

BR

AS

S

Sr. No Current Pulse ON Pulse OFF M.R.R S.R1 7.8125 3 3 0.002296 1.99

2 7.8125 3 5 0.001786 2.37

3 7.8125 3 7 0.001531 1.86

4 7.8125 5 3 0.003827 1.85

5 7.8125 5 5 0.003316 2.07

6 7.8125 5 7 0.002296 1.75

7 7.8125 7 3 0.004082 2.17

8 7.8125 7 5 0.003316 1.91

9 7.8125 7 7 0.002806 2.34

10 14.0625 3 3 0.008418 2.21

11 14.0625 3 5 0.007398 2.22

12 14.0625 3 7 0.004082 2.12

13 14.0625 5 3 0.008929 1.91

14 14.0625 5 5 0.007908 2.04

15 14.0625 5 7 0.005612 2.64

16 14.0625 7 3 0.008416 2.32

17 14.0625 7 5 0.008673 2.76

18 14.0625 7 7 0.007653 2.65

19 23.4375 3 3 0.014031 2.02

20 23.4375 3 5 0.013265 2.11

21 23.4375 3 7 0.014031 2.05

22 23.4375 5 3 0.016837 2.07

23 23.4375 5 5 0.015816 2.12

24 23.4375 5 7 0.017857 2.36

25 23.4375 7 3 0.0125 2.07

26 23.4375 7 5 0.014031 2.39

27 23.4375 7 7 0.011224 2.19

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Analysis of variance (ANOVA) for Brass (MRR)

parameter DOF Sum of squares

SS

Variance

(Mean square)

Variance ratio

(F)

Percentage

contribution

P (%)

Current 2 0.000612694 0.00030635 153.945 90.784

Pulse ON 2 0.00001373 0.00000687 3.407 2.034

Pulse OFF 2 0.00000873 0.00000437 2.196 1.294

Residual

Error20 0.00003974 0.00000199 1 5.88

Total 27 0.000674894 100

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Analysis of variance (ANOVA) for Brass (SR)

parameter DOF Sum of squares

SS

Variance

(Mean square)

Variance ratio

(F)

Percentage

contribution

P (%)

Current 2 0.36736 0.18368 4.39636 22.751

Pulse ON 2 0.27416 0.137086 3.28100 16.979

Pulse OFF 2 0.13746 0.06873 1.64505 8.513

Residual

Error20 0.83569 0.04178 1 51.756

Total 27 1.61467 100

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parameter DOF Sum of squares

SS

Variance

(Mean square)

Variance ratio

(F)

Percentage

contribution

P (%)

Current 2 0.00370929 0.00185465 242.755 89.170

Pulse ON 2 0.000152 0.000076 9.948 3.654

Pulse OFF 2 0.0001457 0.00007285 9.535 3.503

Residual

Error20 0.00015281 0.00000764 1 3.673

Total 27 0.0041598 100

Analysis of variance (ANOVA) for Copper (MRR)

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Analysis of variance (ANOVA) for Copper (SR)

parameter DOF Sum of squares

SS

Variance

(Mean square)

Variance

ratio

(F)

Percentage

contribution

P (%)

Current2 0.44891 0.22446 0.55323 1.895

Pulse ON2 14.82831 7.41416 18.27363 62.598

Pulse OFF2 0.29629 0.14815 0.36514 1.251

Residual

Error20 8.11454 0.40573 1 34.256

Total27 23.68805 100

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In this work, analysis of variance (ANOVA) with Taguchi method is used to

investigate the significant effects on the performance characteristic and the

optimal machining parameter of EDM process.

Finding the result of MRR discharge current is most influencing factor and

then pulse OFF time. From percentage contribution we can clearly say that

MRR and contribution of input parameters are depends on” THERMAL

CONDUCTIVITY” of material.

For high discharge current, copper electrodes show highest MRR, whereas

brass gives good surface finish and normal MRR

Surface roughness was mainly affected by the current and pulse on time. At

higher value of current causes the more surface roughness. Higher surface

finish can be achieved at lower current.

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The optimum levels of various process parameters obtained in this

experimental work are: Copper electrodes gives highest MRR than

Brass electrodes when Discharge current = 23.2475 A, 7 μs pulse on

time, 5 μs pulse off time.

Similarly Brass electrodes gives lowest MRR than copper electrode when

Discharge current = 7.8125 A, 5 μs pulse on time, 7 μs pulse on time.

Brass electrodes gives better surface finishing when Discharge current =

7.8125A, 5 μs pulse on time, 7 μs pulse on time.

Similarly copper electrodes gives poor surface finishing when Discharge

current = 23.4375 A, 7 μs pulse on time, 5 μs pulse on time.

3125-May-13

THANK YOU…..