Structural analysis of electrodischarge machined surfaces of EN31 tool steel

Abstract

During the last two decades, there has been a rapid growth in the development of harder and difficult to machine metals and alloys to fulfill the need of industries. For these alloys, the conventional cutting and machining have been found to be uneconomical. Further, the degrees of accuracy and surface finish attainable by conventional process have been poor. In view of the seriousness of this problem, there is a need for development of newer concepts in metal machining. Electrodischarge machining (EDM) is a non-conventional process which is used for machining of such alloys. This paper presents the details of machining and structural analysis of EDMed surfaces with respect to material removal parameters of the workpiece. Experimental work has been conducted on EN31 tool steel with copper, brass and graphite as tool electrodes. Kerosene oil of commercial grade has been used as dielectric fluid. The data compiled during the experimentation have been used to check the responses in respect of material removal rate (MRR) and surface roughness (Ra). Further, the detailed analysis of structural features of machined surface has been carried out by scanning electron microscope and optical microscope to understand the mode of heat transfer which alternatively affects the structure of the machined workpiece and hence the life of the tool.

Keywords

EDM METAL REMOVAL RATE EN31 STEEL STRUCTURAL ANALYSIS DIELECTRIC

Get full access to this article

View all access options for this article.

References

Rajkumar

K. P.

: ‘Handbook of design, manufacturing and automation’, (ed. Dorf

R. C.

and Kusiak

), Chapter 13, ‘Nontraditional manufacturing processes’; 1994, New York, John Wiley & Sons.

Lin

Y.-C.

, Chen

Y.-F.

, Lin

C-T.

and Tzeng

H.-J.

: ‘Electrical discharge machining (EDM) characteristics associated with elec-trical discharge energy on machining or cemented tungsten carbide’, Mater. Manuf Processes, 2008, 23, 391–399.

K. L.

, Van

B. H.

, Huang

F. Y.

and Chen:

S. C.

‘Improvement of surface finish and surfactant added dielectric’, Int. J. Mach. Tools Manuf, 2005, 45, 1195–1201.

Lee

S. H.

and Li:

X. P.

‘Study of the surface integrity of the machined workpiece in the EDM of tungsten carbide’, J. Mater. Process. Technol., 2003, 139, 315–321.

Ramaswamy

and Blunt

: ‘Effect of EDM process parameters on 3D surface topography’, J. Mater. Sci. Process. Technol., 2004, 148, 155–164.

Puertas

Luis

C. J.

and Alvarez

: ‘Analysis or the influence or EDM parameters on surface quality, MRR and EW of WC—CO’, J. Mater. Process. Technol., 2004, 153–154, 1026–1032.

Pandey

P. C.

and Jillani:

S. T.

‘Electrical machining characteristic of cemented carbides’, Wear, 1987, 116, 77–88.

Payal

H. S.

and Sethi:

B. L.

Non-conventional machining processes as viable alternatives for production with specific reference to electric discharge machining’, J. Sci. Ind Res., 2002, 62, 678–682.

Abbas

N. M.

, Solomon

D. G.

and Bahari:

M. F.

‘A review on current research trends in electrical discharge machining (EDM)’, Int. J. Mack Tools Manuf, 2007, 47, 1214–1228.

10.

Soni

J. S.

and Chakraverti

: ‘Effect of electrode material properties on surface roughness and dimensional accuracy in electro-discharge machining of high carbon high chromium die steel’, J. Inst. Eng. (Ind), 1995, 76, 46–51.

11.

Soni

J. S.

and Chakraverti:

‘Experimental investigation on migration of material during EDM of die steel (T215 Cr12)’, J. Mater. Process. Technol., 1996, 56, (1-4), 439–451.

12.

Khatter

C. P.

and Pandey

O. P.

: ‘Effect of processing parameters on structural features of tungsten carbide after electrical discharge machining (EDM)’, Tribol., Mater. Surf Interf, 2008,2, (2), 65–71.

13.

Soni

J. S.

and Chakraverti

: ‘Investigative study on metal removal rate and wear ratio in EDM of high carbon high chromium die steel’, J. Inst. Eng. (Ind), 1991, 71, (Pt AS2), 32.

14.

George

and Venkatesh:

V. C.

‘Investigations on optimum machining conditions for electro-discharge machining of 5 Cr die steel’, Proc. 9th AIMTDR Conf., Kanpur, India, December 1980, ITT, 327–332.

15.

Raman

K. S.

, Gupta

H. R.

, Singal

A. R.

, Das

P. K.

, Saha

and Mishra:

P. K.

‘EDMing of GT-20 grade of carbide’, Proc. 17th AIMTDR Conf., Warangal, India, January 1997, REC, 290–294.

16.

Guu

Y. H.

, Hocheng

, Chou

C. Y.

and Deng:

C. S.

‘Effect of electrical discharge machining on surface characteristics and machining damage of A1S1 D2 tool steel’, Mater. Sci. Eng. A, 2003, A358, 37–43.

17.

Marafona

and Wykes:

Int. J. Mach. Tools Manuf, 2000, 40, 153.

18.

Mamlis

, Vosniakos

G. C.

, Vaxevandis

N. M.

and Prohszka:

J. Mech. Work. Technol., 1987, 15, 335.

19.

Erden

and Bilgin

: ‘Role of impurities in electrical discharge machining’, Proc. 21st IMTDR Conf., Dept. of Mechanical Engineering, University College of Swansea & Macmillan, UK, September 1980, 345–350.

20.

Singh

and Pandey:

P. C.

‘Surface finish quality in electric discharge machining — a review’, Proc. Natl Sem. on ‘Emerging convergent technologies and system’ (SECTAS 2002), Dyalbagh, India, March 2002, DEI, 462–467.

21.

Lee

H. T.

, Hsu

F. C.

and Tai:

T. Y.

‘Study of surface integrity using the small area EDM process with a copper—tungsten electrode’, Mater. Sci. Eng. A, 2003, A364, 346–356.

22.

Lee

H. T.

and Tai:

T. Y.

J. Mater. Process. Technol., 2003, 142,(3), 676.

23.

K. H.

and Newman:

S. T.

‘State of the electrical discharge machining (EDM)’, Int. J. Mach. Tools Manuf, 2003, 43, 1287–1300.

24.

Singh

, Maheshwari

and Pandey:

P. C.

‘Some investigations into the electric discharge machining of hardened tool steel using different electrode materials’, J. Mater. Process. Technol., 2004, 149, 272–277.

25.

Luis

C. J.

, Puertas

and Villa

: ‘Material removal rate and electrode wear study on the EDM of silicon carbide’, J. Mater. Process. Technol., 2005, 164–165, 889–896.

26.

Bojorquez

, Marloth

R. T.

and Es-Said

O. S.

: ‘Formation of a crater in the workpiece on an electrical discharge machine’, Eng. Fail. Anal., 2002, 9, 93–97.

27.

Marafona

and Chousal

J. A. G.

: ‘A finite element model of EDM based on the Joule effect’, Int. J. Mach. Tools Manuf, 2005, 46, 1–8.