Surface roughness model for micro electrical discharge machining

Abstract

Asperities produced by electrical discharge machining (EDM) are covered by a multitude of overlapping craters, which results in the formation of corresponding workpiece profiles with a specified accuracy and surface finish. This paper proposes a surface roughness model for micro-EDM based on the crater geometry estimation. Surface factors are introduced into the model formulation to take into account the effects of overlapping craters, pockmarks, microcracks, and reattachment of debris in the actual machining process. Based on the experimental results using AISI 4140 as the workpiece, the surface factors are found to be 0.2985 and 0.3443 for the theoretical surface roughness for R_a and R_t respectively. Extension of the surface roughness prediction model to other materials is demonstrated using Ti—6Al—4V. Through this preliminary study, the proposed model generated theoretical results that have an average error of 6.5 per cent for R_a and 4.5 per cent for R_t when compared with the respective experimental results, thereby revealing the potential usefulness of the surface roughness prediction model.

Keywords

micro-electrical discharge machining surface roughness electrothermal model

References

Pandit

S. M.

Rajurkar

K. P.

, ‘A mathematical model for electro-discharge machined surface roughness’ In Proceedings of the Sixth Annual North American Manufacturing Research Conference, 1978, pp. 339–345 (Society of Manufacturing Engineers, Dearborn, Michigan).

Lee

S. H.

X. P.

, ‘Study of the effect of machining parameters on the machining characteristics in electrical discharge machining of tungsten carbide’ J. Mater. Processing Technol. 115 (2001): 344–358.

Keskin

Halkaci

H. S.

Kizil

, ‘An experimental study for determination of the effects of machining parameters on surface roughness in electrical discharge machining (EDM)’ Int. J. Advd Mfg Technol. 28 (2006): 1118–1121.

Jeswani

M. L.

, ‘Roughness and wear characteristic of spark-eroded surfaces’ Wear 51 (1978): 227–236.

Jeswani

M. L.

, ‘Electrical discharge machining in distilled water’ Wear 72 (1981): 81–88.

Mamalis

A. G.

Vosniakos

G. C.

Vaxevanidis

N. M.

Prohaszka

, ‘Macroscopic and microscopic phenomena of electro-discharge machined steel surfaces: An experimental investigation’ J. Mech. Working Technol. 15 (1987): 335–356.

Petropoulos

Vaxevanidis

N. M.

Pandazaras

, ‘Modeling of surface finish in electro-discharge machining based upon statistical multi-parameter analysis’ J. Mater. Processing Technol. 155–156 (2004): 1247–1251.

Tsai

K.-M.

Wang

P.-J.

, ‘Predictions on surface finish in electrical discharge machining based upon neural network models’ Int. J. Mach. Tools Mf 41 (2001): 1385–1403.

Tsai

K.-M.

Wang

P.-J.

, ‘Semi-empirical model of surface finish on electrical discharge machining’ Int. J. Mach. Tools Mf 41 (2001): 1455–1477.

10.

Indurkhya

Rajurkar

K. P.

, ‘Artificial neural network approach in modelling of EDM process’ In Proceedings of the Artificial Neural Networks in Engineering Conference, St Louis, Mussouri, USA, 15–18 November 1992, pp. 845–850 (ASME International, New York).

11.

Rajurkar

K. P.

Z. Y.

, ‘Micro EDM can produce micro parts’ Mfg Engng 125 (2000): 68–70.

12.

Yeo

S. H.

Kurnia

Tan

P. C.

, ‘Electro-thermal modelling of anode and cathode in micro-EDM’ J. Phys. D: Appl. Phys. 40 (2007): 2513–2521.

13.

Carslaw

H. S.

Jaeger

J. C.

, Conduction of heat in solids 2nd edition, 1986 (Clarendon, Oxford).

14.

Thomas

P. H.

, ‘Some conduction problems in the heating of small areas on large solids’ Q. J. Mechanics Appl. Math. 10 (1957): 482–493.

15.

Beck

J. V.

, ‘Large time solutions for temperatures in a semi-infinite body with a disk heat source’ Int. J. Heat Mass Transfer 24 (1981): 155–164.

16.

Brandes

E. A.

Smithells

C. J.

, Smithells metals reference book 6th edition, 1983 (Butterworths, London).