Experimental study on green electrical discharge machining in tap water of Ti–6Al–4V and parameters optimization

Abstract

Ti-6Al-4V is widely used in the aerospace, automobile, and biomedical fields, but is a difficult-to-machine material. Electrical discharge machining (EDM) is regarded as one of the most effective approaches to machining Ti-6Al-4V alloy, since it is a non-contact electro-thermal machining method, and it is independent from the mechanical properties of the processed material. This paper aims to combine grey relational analysis and Taguchi methods to solve the problem of EDM parameters optimization. From the viewpoint of health and environment, tap water as working fluid has good working environment, since it does not release harmful gas. The process parameters include discharge current, gap voltage, lifting height, negative polarity and pulse duty factor. The electrode wear ratio (EWR), material removal rate (MRR) and surface roughness (SR) as objective parameters are chosen to evaluate the whole machining effects. Experiments were carried out based on Taguchi L 9 orthogonal array and grey relational analysis, and then verified the results through a confirmation experiment. Compared the machining parameters A 1 B 1 C 3 D 2 with A 1 B 2 C 2 D 2 , MRR increased from 1.28 mm 3 /min to 2.38 mm 3 /min, EWR decreased from 0.14 to 0.10 mm 3 /min and SR decreased from Ra 2.37 μm to Ra 1.93 μm. The process parameters sequenced in order of relative importance are: the ratio of pulse width to pulse interval, discharge current, lifting height and gap voltage. The results showed that using tap water machining Ti-6Al-4V material can obtain high MRR, decrease the machining cost and have no harmful to the operators and the environment.

Surface modification of TiNi-based shape memory alloys by dry electrical discharge machining

“…3(b) and (d), cracks can be seen on the surfaces of both EDMed SMAs, and cracking appears to have occurred more frequently on the EDMed surfaces subjected to longer pulse duration. Comparing these findings with results of EDM in distilled water (Hasç alık and Ç aydaş , 2007) and kerosene (Tang and Du, 2014), there is no significant difference in surface characteristics of alloys EDMed in gas and liquid electrolytes. The cross-sectional SEM micrographs of the EDMed Ti 50 Ni 50 SMAs ( Fig.…”

Modeling and experimental study on breakdown voltage (BV) in low speed wire electrical discharge machining (LS-WEDM) of Ti-6Al-4V

“…Titanium alloys are the notoriously "difficult-to-machine" materials, which possess many attractive properties like outstanding mechanical and thermal properties, excellent corrosion resistance, and high strength-to-weight ratio [5,6]. Thus, titanium alloys have become one of the most widely used materials for successful application in aerospace, automotive, and biomedical industries [7]. The advantages of LS-WEDM make it to be the best alternative to machine titanium alloys.…”

Study the effect of black layer on electrode wear ratio in powder mixed electric discharge machining of titanium alloys

“…To optimise a single performance characteristic, Taguchi methodology is applied by the various researchers; however, some researchers (Kao et al, 2010;Kumar et al, 2012;Tang and Du, 2014), applied Taguchi orthogonal array and grey relational analysis to investigate the multi performance measures.…”