Edm Test Paper

8/12/2019 Edm Test Paper

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Aim

To acquaint the knowledge of various thermal models considering conduction mode of heat

transfer; and a comparative study to estimate crater depth, profile due to heat source.

Objectives

1. To study various accepted thermal models in Electrical Discharge Machining process

. To understand the effect of variation of pulse time, leading towards variation in desired

output in conte!t with various thermal models

". To acquire knowledge regarding erosion characteristics in EDM

#. To study the temperature distri$ution along the crater depth

Prerequisites

%or $etter understanding of the e!periment a candidate should acquire following knowledge

1. Modes of &eat transfer.

. 'asic knowledge of Electrical Discharge Machining

". (arious terminologies related to pulse.

#. )nderstanding of various relevant terms vi*. latent heat of melting, latent heat of

vapori*ation, latent heat of evaporation.

+. ome hands on e!perience for M-T-' programming.

Theory

E!perimental etup

/rocedure

http://coep.vlab.co.in/?sub=34&brch=105&sim=238&cnt=1








imulator

/ostTest

0onclusion

Theory:

-mong the various models developed $y different researchers, the $asic accepted Thermal

models are represented here along with assumptions.

Snoeys’s Model 12314 noeys proposed a first ever widely acknowledged thermal model for

EDM process and %igure ".1 shows graphically representation of the model.

%eatures

1. &eat source is assumed to $e of disk shape on the surface of electrode.

. 0athode surface is assumed to $e insulated at the outer area.

". 5adius at insulated surface is assumed 166 times, the radius of disk heat source.










#. - method to account the change in radius of heat source with time is proposed.

The schematic diagram of (an Di<ck8s model is illustrated in the %igure ". .

%igure ". (an Di<ck8s model

The superposition principle and separation of varia$les were applied to the partial differential

equation and the solution of the temperature distri$ution is given as

".4

%or,

eck’s Model 12=14 is also another disk heat source model. This mode is not developed

specifically for the EDM process $ut resem$les to the one. %igure "." shows the schematic

representation of the model.

%eatures

1. - disk shaped region over material surface is considered to $e heated $y heat flu!.



. The entire electrode surface is considered to $e insulated; e!cept over the circular region

where the heat flu! strikes the material surfaces.

-s the model is not developed specifically for the EDM process, the heat flu! did not take into

account the fraction of energy transferred to the cathode.

%igure "." 'eck8s model

The temperature distri$ution is given $y equation "."4,

"."4

here;

!ilani’s Model 12=", 12=>4 and /.0. /andey of )niversity of 5urkee proposed a thermal model

of EDM in 12=". %igure ".# shows the schematic representation of the model.

%igure ".# ?ilani8s model

%eatures

1. This model assumes that the heat from the plasma channel is transferred to the workpiece

or tool only $y conduction.

. The electrode is a semi7infinite $ody with radius r o.



%igure ".+ Di$itonto8s model

The temperature distri$ution was given $y 0arslaw and ?aeger in12+> as,

This equation assumes constant current @ during the pulse. -t the melt radius 5,

-long the interface where the phase change takes place 4 the equation ".=4 holds

where, : heat of fusion, : molten cavity volume.

'$ Salonitis’s Model 66>4

%eaturesA @t is assumed that the distance from the workpiece surface at which the temperature

e!ceeds the melting point coincides with the crater depth, neglecting the formation of a

recast layer. @t is completely new and simple approach of thermal modeling where new concept

of erosion front velocity is introduced

and %igure ".> represents the schematic diagram for the model

%igure ".> alonitis8s Model



with three chief controlling parameters vi*. Ton, Toff , Toff1. -ppropriate machining operation is

achieved with the help of adequate wire feed control and dielectric flushing rate.

urfce roughness of machined component was measured using Taylor7&o$son surface roughness

tester ModelA urtronic7+4. eight of the material was taken on -fcoset Electronic 'alance

ModelA %G7#664. Tektroni! TD61 model digital oscilloscope was connected to the machine

to measure num$er of pulses.



+ire (lectric Dischar,e Machine

S*eci-ications:(oltage sta$ili*ers " /hase4

1. E00)T A 3.+ H(-, I#1+ ( line to line

. @nput voltage A "16 ( to #1> ( line to line, i.e. 1=6736 (Jphase

". utput voltage A #1+ ( line to line, i.e. #6 ( phase to neutral

#. utput voltage regulation A K 19J phase of output voltage

+. (oltage correction rate A "+ (J sec

>. Termination A + ways socket on rear door 6 -4

3. verload protection A ith @EMEL contactor and " phase

thermal overload relay

=. ther protection A ingle phasing presetter, over7voltage trip

T5-(E 5-LCE -G@ E00)T

LC@T)D@L-

G +6mm

) K1+mm

-TE5-

"+6mm

( .1+mm

(E5T@0- N 66mm



5H/@E0E @NE E00)T

Ma!. 5H/@E0E @NE +3+ O ="+ O 66mm

Ma!. 5H/@E0E t 3+ Hg

Main ta$le feed rate =6 mmJmin

5esolution

ire feed rate

6.661 mm

6716 mJmin

Main ta$le feed rate =6 mmJmin

ire guide type Diamond closed

ire electrode diameter 6.+, TD, 6. /T@L-

Taper cutting

Ma!. Taper -ngle

K +PJ166mm

Procedure

- comparative study of an point and disk heat source model is presented herewith. The

workpiece material considered for the e!periment is 0opper with following properties. /roperty (alue

1. m 13> k?Jkg

. v +6>+ k?Jkg

". Tm 1"+3.33H

#. T$ =#6.1+ H



M44 calculation

(olume of crater, (c was calculated using following relationA

# 3alculations usin, Salonitis Model

5adius of heat source was calculated using following equationA

)sing the constants - and ' used $y 5e$elo et al. radius of crater was calculatedA

#$/ M44 calculation

%or copper,

-:13#", ':6."3 RS

(olume of a single crater was calculated $yA

Material removal rate was calculated using the equationA

#$2 Sur-ace 4ou,hness A**roach:

alonitis also proposed a different approach which esta$lished relationship $etween radius of

crater and surface roughness. 'ased on the para$olic geometry of the crater, which is the $asic

assumption of this model, following relationship was proposedA

-fter cutting, surface roughness of the machined component was measured on Taylor7&o$son

surface roughness tester. 'ased on those values, new crater radius were estimated.

3onclusion

The 0onclusions deviveried from the e!periment are summari*ed as $elowA



1. /oint heat source model is one of the easiest thermal models for determining stock

removal rate corresponding to temperature gradient within the surface.

. &eat transfer is assumed to $e uniform in three directions giving a hemi7spherical

temperature profile.

". The disk heat source thermal models are considered to $e more nearer to the actual

processes those involving higher pulse frequencies4. %orm this one can predict the recast layer,

recrystali*ed depths which can predict the appro!imate surface topography and integrity

qualitatively4.

4(5(4(63(S

1. -M &and$ook, (olume , /roperties and selectionA Lonferrous -lloys and pecial7

/urpose MaterialsU

. 'aya*itoglu ., *isik M., 12==4, Elements of &eat TransferU, McCraw &ill @nternational

Editions, pp.1#671#".

". 'eck ?. (., 12=1 $4, arge time solutions for temperatures in a semi7infinite $ody with a

disk heat sourceU, @nternational ?ournal of &eat and Mass Transfer, (ol. # 14, pp. 1++

1>#.

#. 'eck ?. (., 12=1a4, Transient temperatures in a semi7infinite cylinder heated $y a disk heat

sourceU, @nternational ?ournal of &eat and Mass Transfer, (ol. # 164, pp. 1>"11>#6.

+. 0arslaw &. ., and ?aeger ?. 0., 12+24, 0onduction of &eat in olidsU, nd Edition,

0larendon /ress, !ford.

>. Di'itonto D. D., Eu$ank, /. T., /atel, M. 5., 'arrufet, M. -., 12=24, Theoretical models

of the electrical discharge machining process @A - simple cathode erosion modelU, ?ournal

of -pplied /hysics, (ol.>>, pp. #62+#16".



3. Di'itonto D. D., Eu$ank, /. T., /atel, M. 5., 'arrufet, M. -., 12=24, Theoretical models

of the electrical discharge machining process @@A The anode erosion modelU, ?ournal of

-pplied /hysics, (ol.>>, pp. #16##111.

=. Chosh -., and Mallik, -, 66=4, Manufacturing ciencesU E/ Lew Delhi, pp. "=>7"26.

2. &asiguchi H., Motoki, M., 12>34, Energy distri$ution at the gap in Electric discharge

machiningU, -nnals of 0@5/, (ol. 1#, pp. #=+7#=2.

16. Harafu<i &., ept. 12>#4, Development of researchers and applications of spark erosion

and electrolytic machining in ?apanU, -nnals of 0@5/.

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econd Edition, pp. 3>= -ppendi! 074.

1. /atel M. 5., 'arrufet M. -., Eu$ank /. T., Di$itonto D. D., 12=24, Theoretical models of

the electrical discharge machining, process. @@. The anode erosion modelU, ?ournal of

-pplied /hysics, (ol. >> 24, pp. #16##111.

1". alonitis H, 66>4, Thermal modeling of the material removal rate and surface roughness

for die7sinking EDMU, @nternational ?ournal of -dvanced Manufacturing Technology, vol.

#, pp. "1>7"".

1#. noeys 5., (an Di<ck %. ., 12314, @nvestigation of electro discharge machining operations

$y means of thermo7mathematical modelU, -nnals of 0@5/, (ol. 6 14, pp. "+"3.

1+. (an Di<ck %. ., 123#4, &eat 0onduction Model for the 0alculation of the (olume of the

Molten Metal in Electric DischargesU, ?. /hy. DA -ppl. /hy., vol. 3 >4, pp. =22216.

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5urther 4eadin,s:

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instantaneous propagationU, 0ompte 5endus, (ol. #3, pp. #"1#"".



. Dekeyser . ., and noeys, 5., 12=24, Ceometrical accuracy of ire EDMU,

/roceedings of the @nternational ymposium for Electro Machining, @EM724 Lagoya, pp.

>7 ".

". Dhanik andeep, ?oshi uhas, Lovem$er 66+4, Modeling of a ingle 5esistance

0apacitance /ulse Discharge in Micro7Electro Discharge MachiningU, ?ournal of

Manufacturing cience and Engineering, (ol. 13 J 3+2.

#. %rankel ?. @., 'rain (ick, *isik, M. L., 12=34, Ceneral formulation and analysis of

hyper$olic heat conduction in composite mediaU, @nternational ?ournal of &eat and Mass

Transfer, (ol. "6, Lo.3, pp. 12"71"6+.

+. ?ennes, M., noeys, 5., and Dekeyser, .,?anuary 12=#4, 0omparison of various

approaches to model the thermal load on the EDM7 wire electrodeU, -nnals of 0@5/, (ol.

"", pp.2"7 2=.

>. ?ilani .T., /andey, /.0. 12=4, -nalysis and modelling of EDM parametersU, /recision

Eng. # #4, pp. 1+1.

3. ?ilani .T., /andey, /.0., 12="4, -nalysis of surface erosion in electrical discharge

machiningU, ear =# "4, pp. 3+=#.

=. iao . , and u, . /., 66#4 tudy of specific discharge energy in EDM and its

applicationU @nternational ?ournal of Machine Tool and Manufacture (ol. ##, pp.1"3"7

1"=6.

2. Masu*awa T., %un<ino M., and Ho$ayashi H., ?anuary 12=+4, ire electro discharge

grinding for micro machining,U -nnals of 0@5/, (ol."#, pp. #"17 #"#.

16. Tosun L., 0ogun 0., 66"4, -n investigation on wire wear in EDMU, ?ournal of

Material /rocess Technology, (ol. 1"#"4, pp. 3"3=.

11. (ernotte M. /., 12>14, ome possi$le complications in the phenomena of thermalconductionU, 0omptes 5endus, (ol. +, pp. 1267121, ">27 "31.

1. ang . M., and 5a<urkar H. /., 1224, Effect of Thermal oad on ire 5upture in

EDMU, Transactions of L-M0@, (ol. 6, pp. 1"27 1##.



1". ang . M., and 5a<urkar H. /., 1224, Monitoring parking %requency and /redicting

ire 'reakage in EDMU, -ME special volume on ensors and ignal /rocessing for

Manufacturing, /ED (ol. ++, pp. #27>#.

1#. iggert D. 0., 12334, -nalysis of early7 time transient heat conduction $y method of

characteristicsU, -ME ?ournal of &eat Transfer, (ol. 22, pp. "+7#6.

1+. eo . &., Hurnia ., Tan /. 0., 66=4, 0ritical assessment and numerical comparison of

electro7thermal models in EDMU, ?ournal of Materials /rocessing Technology, (ol.6", pp.

#1+1.

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