Evolutionary programming method for modeling the EDM parameters for roughness

(BQ) The method of electrical discharge machining (EDM), one of the processing methods based on non-traditional manufacturing procedures, is gaining increased popularity, since it doesnot require cutting tools and allows machining involving hard, brittle, thin and complex geometry
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Evolutionary programming method for modeling the EDM parameters for roughnessj o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 2 0 0 ( 2 0 0 8 ) 347–355Assab79PM, whichdemonstrates thechemical properties ofthe DIN 1.2379 coldj o u r n a l h o m e p a g e : w w tool l s e v i e r . c o m / l o c a t e / j m a t p r o t e cwork w . e steelEvolutionary programming method for modelingthe EDM parameters for roughness¨Ozlem Salman, M. Cengiz Kayacan ∗University of Suleyman Demirel, CAD/CAM Research and Application Center, 32300 Isparta, Turkeya r t i c l ei n f oa b s t r a c tArticle history:The method of electrical discharge machining (EDM), one of the processing methods basedReceived 14 April 2006on non-traditional manufacturing procedures, is gaining increased popularity, since it doesReceived in revised formnot require cutting tools and allows machining involving hard, brittle, thin and complex7 September 2007geometry.Accepted 10 September 2007By using different EDM parameters (current, pulse on-time, pulse off-time, arc voltage), theRa (␮m) roughness value as a result of application of a number of copper electrode-hardenedpowder metals (cold work tool steel) to a work piece has been investigated, in this study. AtKeywords:the same time, roughness values obtained from the experiments that have been modeled byElectrical discharge machiningusing the genetic expression programming (GEP) method and a mathematical relationshipGenetic expression programminghas been suggested between the GEP model and surface roughness and parameters affectingSurface roughnessit. Moreover, EDM has been used by applying copper, copper–tungsten (W–Cu) and graphiteelectrodes to the same material with experimental parameters designed in accordance withthe Taguchi method. Results obtained from this study have been compared among eachother and similar studies in the literature.© 2007 Published by Elsevier B.V.1.IntroductionThe first EDM application was carried out by Mr. and Mrs.Lazarenko in the Technical Institute of Moscow during theSecond World War. The fundamentals of EDM can be tracedas far back as 1770, when English chemist Joseph Priestly discovered the erosive effect of electrical discharges or sparks.However, it was only in 1943 at the Moscow University thatMr. and Mrs. Lazarenko exploited the destructive propertiesof electrical discharges for constructive applications (Puertasand Luis, 2004). The EDM method, one of the methods used inthe machining industry, is becoming a preferred manufacturing method as it does not require the use of cutting tools formaterials that conduct electricity and ensures low productioncosts.∗Corresponding author.E-mail address: ckayacan@mmf.sdu.edu.tr (M.C. Kayacan).0924-0136/$ – see front matter © 2007 Published by Elsevier B.V.doi:10.1016/j.jmatprotec.2007.09.022A non-traditional manufacturing method, the electro erosion process does not depend on the hardness of material andoffers a way to process materials of very complex geometrywith very fine and high precision by using cheap electrodematerials, which makes it a preferred method.The most important advantage of this process is its independence of the machined material’s mechanical propertiesand independent from the cutting force. Thus, materials ofhigh hardness, brittleness and strength that are difficult-tocut can be machined easily at desired shape (Tsai et al., 2003).EDM is a machining method based on the principle of controlled application of high-frequency electric discharge ontoa work piece that conducts electricity thus detaching smallparticles from the work piece by melting and evaporatingthem. The machining performance in EDM processes consists348j o u r n a l o f m a t e r i a l s p r o c e s s i n g t e c h n o l o g y 2 0 0 ( 2 0 0 8 ) 347–355of the material removal rate (MRR), electrode wear (EW), surface roughness (SR) and surface quality. The effort made inliterature conducted so far has been to increase the material removal rate, with the studies aimed to erode as muchmaterial as possible. Technologies still face some difficultiesin the increase of the MRR value. Studies to improve this proportion are going on (Puertas and Luis, 2004; Fuling et al., 2004;Amorim and Weingaertner, 2004; Valentincic and Junkar, 2004;˘Lin et al., 2000; Erden and Kaftanoglu, 1981).MRR depends on the properties of the dielectric fluid usedin the EDM as much as it depends on the properties of thework piece material and the electrode. Minimum wear of theelectrode that removes the materials from the work pieceby conducting the current is required in EDM applications.A number of researches have been made by adding variousadditives to the dielectric fluid in order to decrease the electrode wear rate, obtaining better results compared to purefluids (Valentincic and Junkar, 2004; Luis et ...