Enhanced Material Removal Rate and Surface Quality of H13 Steel in Electrical Discharge Machining With Graphite Electrode in Rough Machining

International Journal o f Scientific Engineering and Technology

Volume No.4 Issue N o.2, pp : 104-109

(ISSN : 2277-1581)

01 Feb2015

u s e r

Enhanced Material Removal Rate and Surface Quality of H13 Steel in

Electrical Discharge Machining With Graphite Electrode in Rough Machining

Banh Tien Long1, Ngo Cuong2, Nguyen Huu Phan2, Hoang Anh Toan3 and Pichai Janmanee4

'Hanoi University of Science and Technology, Hanoi, Vietnam

2Technical-economicscollege, Thai Nguyen University, Vietnam

3Thai Nguyen university of Technology, Thai Nguyen University, Vietnam

4Rajamangala University of Technology Krungthep, Bangkok,Thailand

Abstract: Enhanced productivity and workpiece surface

quality after electrical discharge machining (EDM) is a

concern o f many researchers. Jn this study, the effect o f

powder concentrations on material removal rate (MRR),

surface roughness (SR) and topography surface in powder

mixed EDM (PMEDM) was investigated. The experimental

studies were conducted keeping the various parameters like

current, voltage and pulse time constant while using varying

concentrations o f titanium powder. Experimental research

methods were employed to study performance characteristics in

the machining o f H13 steel using PMEDM with a graphite

electrode. The results revealed that the concentration of

titanium powder has a powerful influence on the MRR, SR and

topography surface in PMEDM.

Keys word: EDM ; PM ED M ; M RR; H13; titanium powder.

1. IN T R O D U C T IO N

A m o n g n o n -tra d itio n a l m a c h in in g m e th o d s, E D M h a s b e e n

the m o st p o p u la r a p p lic a tio n in m e c h a n ic a l e n g in e e rin g

te c h n o lo g y . T h is m e th o d u se s th e e n e rg y fro m th e sp a rk s

g e n e ra te d in th e d ie le c tric flu id to m e lt a n d e v a p o ra te b o th

e le c tro d e an d m a c h in in g m a te ria l. T h e a d v a n ta g e s o f th is

m e th o d are the m a c h in in g o f c o n d u c tiv e m a te ria ls w ith v e ry

hig h h a rd n e ss a n d stre n g th . S u rfa c e s w ith c o m p le x sh a p e s can

also b e m a c h in e d ; th is w o u ld b e d iffic u lt u s in g th e tra d itio n a l

p ro c e ss in g m e th o d s. H o w e v e r, th e g re a te st d ra w b a c k o f this

m e th o d is p ro d u c tiv ity an d also th e p ro c e ss in g q u a lity is n o t

h ig h . R e c e n tly a so lu tio n h a s b een p ro p o s e d to o v e rc o m e th ese

lim ita tio n s o f E D M an d th e re is a lo t o f p ro fe s sio n a l in te re st in

th is field . T h e re h a v e b een m a n y re se a rc h d o c u m e n ts p u b lish e d

c o n c e rn in g th e u se o f m e ta ls o r a llo y p o w d e rs m ix e d w ith

d ie le c tric flu id an d u se d in E D M .

S o m e o f th e se p o w d e rs (c o p p e r (C u ), s ilic o n (S i), a lu m in u m

(A l), c h ro m iu m (C r), tu n g s te n (W ), v a n a d iu m (V ), n ic k e l (N i),

silic o n c a rb id e (S iC ), a lu m in u m o x id e (A 1 2 0 3 ) and

m o ly b d e n u m d is u lfid e (M o S 2 )), w ith siz e < 1 0 0 |.im w e re u se d

an d m ix e d in to th e d ie le c tric flu id to im p ro v e p ro d u c tiv ity an d

p ro c e ss in g q u a lity in E D M . T h e p o w d e r, w h e n m ix e d in to the

d ie le c tric flu id fo rm e d a se rie s o f e le c tric sp a rk s w h ic h

d isc h a rg e d in o n e p u lse o f E D M as sh o w n in F ig u re 1 [1]. W h en

the p o w d e r w as m ix e d into th e d ie le c tric flu id , resu lts sh o w e d

th a t M R R in c re a se d . S u rfa c e ro u g h n e ss a n d th e n u m b e r o f

c ra c k s on the s u rfa c e m ic ro stru c tu re re d u c e d w ith m a c h in in g

a n d th e im p a c t o f th e th erm al la y e r also re d u c e d . S tre n g th

ero sio n in c re a se d a n d a la y e re d a llo y w ith g o o d m e c h a n ic a l

p ro p e rtie s fo rm e d o n th e m a c h in in g s u rfa c e [2 ], F ig u re 2 a n d 3.

S ilico n p o w d e r w h e n m ix e d in to th e d ie le c tric flu id fo r

m a c h in in g steel H I 3 e n h a n c e d th e q u a lity o f th e m a c h in in g

su rfa c e [3], A lu m in u m p o w d e r w ith a v e ra g e siz e m ix e d in to the

d ie le c tric flu id fo r m a c h in in g ste el S K H -5 1 sh o w e d h ig h su rfa c e

s m o o th n e ss, b u t w h e n m a c h in in g steel S K H -5 4 re su lte d in lo w

su rfa c e sm o o th n e s s [4], T h e c h a n g e in th e c o n c e n tra tio n o f Al

p o w d e r m ix e d w ith th e d ie le c tric flu id h ad a p o w e rfu l in flu e n c e

on th e q u a lity o f th e E D M p ro c e s s [5]. T h e d ia m e te r an d d ep th

o f th e c ra te rs o n th e su rfa c e w h e n m a c h in in g u sin g th e E D M

te c h n iq u e d e c re a s e d w h e n p o w d e r w a s m ix e d in to th e d ie le c tric

flu id [6], S ilico n p o w d e r an d th e c ro ss -s e c tio n a l a rea o f the

e le c tro d e s bo th h ad an e ffe c t on th e v a lu e s o f su rfa c e ro u g h n e ss

an d th e s tru c tu re o f th e m a c h in in g s u rfa c e [7], V a lu e s o f su rfa c e

ro u g h n e ss ra n g e d fro m 0 .0 9 to 0 .5 7 |im w h e n th e su rfa c e a re a o f

m a c h in in g v a rie d fro m 1 to 64 c m 2 . S u rfa c e ro u g h n e ss , w h ite

la y e r th ic k n e ss an d th e sh a p e an d d e p th o f th e c ra te rs a re all

re la te d to th e s u rfa c e m a c h in in g a re a an d th is h a s b e e n d e s c rib e d

b y m a th e m a tic a l e q u a tio n s [8 ]. A l a n d S iC p o w d e rs w e re m ix e d

in to th e d ie le c tric flu id a n d su rfa c e ro u g h n e ss w a s s e le c te d fo r

a n a ly sis [9]. R e su lts fro m re se a rc h h a v e fo u n d th a t th e

te c h n o lo g ic a l p a ra m e te rs o f q u a lity P M E D M h a v e a c h ie v e d the

b e st su rfa c e m a c h in in g . C o m p a rin g th e e ffe c t o f C u p o w d e r

m ix ed w ith g ra p h ite p o w d e r in to th e d ie le c tric flu id sh o w e d that,

th e g ra p h ite p o w d e r sig n ific a n tly re d u c e d th e tool w e a r rate

(T W R ). T h is e n h a n c e d th e d u ra b ility o f th e e le c tro d e an d

im p ro v e d m a c h in in g a c c u ra c y [1 0 ], A l p o w d e r m ix e d in to the

d ie le c tric flu id b e h a v e s lik e p u re w a te r fo r m a c h in in g a W 3 0 0

steel m o u ld b y E D M [1 1 ], T h is re d u c e d th e th ic k n e ss o f th e

w h ite la y e r o n the s u rfa c e m a c h in in g la y e r o f th e w o rk p ie c e ,

c o m p a re d w ith n o p o w d e r in th e d ie le c tric flu id . In c re a s in g th e

c o n c e n tra tio n o f p o w d e r re su lte d in a d e c re a s e in th e w h ite la y e r

th ick n ess. G ra p h ite an d n ick el p o w d e rs w h e n in tro d u c e d in to the

d ie le c tric flu id in E D M in c re a se d M R R w h ile T W R re d u c e d and

m a c h in in g a c c u ra c y a n d s u rfa c e m a c h in in g q u a lity in c re a se d

[1 2 ], W h en Al p o w d e r w as a d d e d to th e d ie le c tric flu id su rfa c e

ro u g h n e ss v a lu e s re d u c e d an d in c re a s in g c o n c e n tra tio n s o f

p o w d e r led to fu rth e r su rfa c e ro u g h n e ss re d u c tio n [1 3 ], W h en

larg e a m o u n ts o f tu n g ste n p o w d e r (0 .2 5 % to 2 .8 9 % ) w e re m ix e d

w ith th e d ie le c tric flu id th e tu n g ste n m ig ra te d to the m a c h in in g

s u rfa c e an d in c re a se d the m ic ro s c o p ic s u rfa c e h a rd n e ss b y 100%

[14], T h is in crease d th e d u ra b ility o f th e m a c h in in g to su rfa c e

c o rro sio n . T h e c o n c e n tra tio n an d siz e o f S iC p o w d e r m ix e d into

th e d ie le c tric flu id in flu e n c e d M R R , T W R a n d S R [1 5 ]. T h e

p ro d u c tiv ity an d q u a lity o f su rfa c e m a c h in in g u s in g P M E D M is

h ig h e r th a n ju s t u sin g E D M [1 6 ], an d th e m a c h in in g tim e o f

p ro d u c ts is re d u c e d . It is n e c e s s a ry to e x te n d th e s e a rc h o f

d iffe re n t ty p e s o f p o w d e r m a te ria ls an d in v e s tig a te th e ir

IJSET@2015 Page 104