Insights into process innovation through ultrasonically agitated ...

Materials and Manufacturing Processes

ISSN: 1042-6914 (Print) 1532-2475 (Online) Journal homepage: http://www.tandfonline.com/loi/lmmp20

Insights into process innovation through ultrasonically agitated concentric flow dielectric streams for dry wire electric discharge machining Bharat C. Khatri, Pravin P. Rathod, Janak B. Valaki & C. D. Sankhavara To cite this article: Bharat C. Khatri, Pravin P. Rathod, Janak B. Valaki & C. D. Sankhavara (2017): Insights into process innovation through ultrasonically agitated concentric flow dielectric streams for dry wire electric discharge machining, Materials and Manufacturing Processes, DOI: 10.1080/10426914.2017.1415442 To link to this article: https://doi.org/10.1080/10426914.2017.1415442

Published online: 22 Dec 2017.

Submit your article to this journal

Article views: 13

View related articles

View Crossmark data

Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=lmmp20 Download by: [14.139.110.146]

Date: 31 December 2017, At: 21:33

MATERIALS AND MANUFACTURING PROCESSES https://doi.org/10.1080/10426914.2017.1415442

none defined

Insights into process innovation through ultrasonically agitated concentric flow dielectric streams for dry wire electric discharge machining Bharat C. Khatria, Pravin P. Rathodb, Janak B. Valakic, and C. D. Sankhavarad Mechanical Engineering Department, L. D. College of Engineering, Ahmedabad, Gujarat, India; bMechanical Engineering Department, Government Engineering College, Bhuj, Kutch, Gujarat, India; cMechanical Engineering Department, Government Engineering College, Bhavnagar, Gujarat, India; dMechanical Engineering Department, School of Engineering, RK University, Rajkot, Gujarat, India

Downloaded by [14.139.110.146] at 21:33 31 December 2017

a

ABSTRACT

ARTICLE HISTORY

Application of gaseous dielectric in place of liquid dielectric for wire electric discharge machining (WEDM), popularly known as dry wire electric discharge machining (DWEDM), offers technological solutions to some environmental and metallurgical issues pertaining to process. However, conventional side jet stream of dielectric in dry WEDM renders ineffective debris removal from sparking gap to cause unwanted arcing. Moreover, side thrust on the wire surface tends to induce wire vibrations and results into uneven geometrical profiles. To harness full potential of DWEDM technology, it is imperative to improve cutting characteristics of process by minimizing the adverse impacts of side jet stream of dielectric. In this research work, the authors have conceptualized and demonstrated the idea of using concentric flow pattern of gaseous dielectric as a novel technological solution to limitations of DWEDM process by introducing ultrasonic-agitated concentric dry wire electric discharge machining (UCDWEDM). Experiments have been performed on Ti–6Al–4V material. Ultrasonically agitated pressurized air streams were supplied through indigenously developed concentric and side flow nozzles mounted on experimental set up. The experimental results showed that concentric flow mode of dielectric supply has outperformed the conventional side flow mode with 42% higher CV, 22% lower SR, and 8% lesser KW. Process mechanism of UCDWEDM is based on high velocity of air in concentric flow and ultrasonicagitation in spark gap and suggested that UCDWEDM has potential to replace conventional dielectric supply system in DWEDM.

Received 4 February 2017 Accepted 14 November 2017

Introduction Wire electric discharge machining (WEDM) is a highly popular variant of spark erosion process. The process utilizes series of high frequency discrete electrical discharges applied between workpiece and thin wire, which facilitates dielectric breakdown in the sparking gap, hence results in 8000–12,000 K temperature in that zone. The high temperature generated favor localized melting then vaporization of both material. Since its introduction in 1960s, WEDM process satisfied demand in precision machining industries for making variety of components economically and at faster production rate.[1–3] Deionized water is generally used as dielectric fluid for WEDM process. However, hazardous emissions and toxic fumes, such as CO, N2O, O3, and aerosols are produced due to decomposition of water, which are injurious to operator health. Moreover, recycle, reuse, nonbiodegradability of debris mixed contaminated deionized water is a serious concern pertaining to environmental impact.[4] Dielectric liquids contribute to 23.1% in total environmental impact of WEDM process.[5] In addition, there is a chance of bacteria growth in dielectric water tank, which tend to cause bacterial hazard.

KEYWORDS

Concentric; dielectric; dry; flow; side; Ultrasonic; WEDM

Dry wire electric discharge machining (DWEDM) is a green and environment friendly technology variant of WEDM, wherein, liquid dielectric is replaces by gaseous medium with a view to minimize the severity of the generation of hazardous gas and waste from the dielectric liquid. DWEDM was first practiced in 2000 by Furudate and Kunieda[6] and the fundamental characteristics of process for finish cutting were investigated using pressurized air instead of deionized water or hydrocarbon oil. DWEDM produced significantly better accuracy, narrower gap length, and straight finished surface, due to lesser vibration, and deflection of the wire because of negligible process reaction forces compared to forces in conventional WEDM.[7] However, DWEDM produce poor material removal rate (mm3/min) (MRR) compare to conventional WEDM because of frequent short circuits due to poor exclusion of debris from spark gap.[8] Ineffective debris evacuation from the gap and wire vibration due to impact of high velocity side jet, wire breakage occurred, and resulted in low material removal rate and poor shape accuracy.[9] For the prevention of debris stagnation and smooth exclusion of debris, high discharge rate from the nozzles was used but it may cause breakage of wire.[10,11] In addition, unsteady flow field by side flow jet of

CONTACT Bharat C. Khatri [email protected] Mechanical Engineering Department, L. D. College of Engineering, Ahmedabad, Gujarat 380016, India. Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/lmmp. © 2017 Taylor & Francis

2

B. C. KHATRI ET AL


air and debris movements in DWEDM is difficult to observe.[12] Several researchers experimented ultrasonic vibration assistance in DEDM process for improvement in performance and observed significant improvement in MRR.[13] Improvement in performance of DWEDM process is still demanded for commercial viability and operator friendliness. The present research is focused for performance improvement in DWEDM by applying ultrasonic vibrations and concentric flow of pressurized air around wire. Experimental research performed to describe the comparative performance of proposed ultrasonic-agitated concentric dry wire electric discharge machining (UCDWEDM) over existing DWEDM with ultrasonic (side flow ultrasonic-agitated side dry wire electric discharge machining (USDWEDM)) to analyze cutting velocity (CV) in mm/min, Surface roughness (SR) in µm, and Kerf width (KW) in mm.

Materials and Methods Titanium alloy (Ti–6Al–4V grade 5) sheet of 1.2 mm thickness (chemical composition as per Table 1) was used as workpiece material for this research. It is used for precision parts manufacturing for specialized applications due to its high strength temperature resistant properties, outstanding corrosion resistance, and biocompatibility.[14,15] Molybdenum wire of 0.18 mm diameter was used as wire electrode for the experiments due to its high tensile strength. The experiments were performed on CNC WEDM machine (Make: Jiang Nan Saitec, Model no: DK-7720). The experimental setup was developed to provide ultrasonic agitations to the dielectric streams with side and concentric flow approaches. The schematic of the setup is shown in Fig. 1a and actual photograph of setup is shown with details in Fig. 1b. As a part of the setup development, a concentric flow nozzle was developed and manufactured by rapid prototyping machine (Make: STRATASYS, Model: Dimension SST 1200es) to supply compressed air in the spark gap. The nozzle has a 2 mm hole opening with 1 mm nozzle tip distance. An ultrasonic generator of 20 kHz frequency and titanium alloy-based ultrasonic horn were used for the experiments (Make: Roop Telesonic, Model: SG-24-500 P). Feasible and adjustable five control parameters with five levels have been carefully chosen to assess the performance of the suggested UCDWEDM process as mentioned in Table 2. Fixed experimental parameters are shown in Table 3. Experiments were performed using USDWEDM and UCDWEDM approaches. Total 25 sets of experiments have been performed for each approach with 25 cutting length. One variable at time experimentation methodology, where only one variable is to be varied keeping other variables at constant, was used for five control parameters viz. current (I), pulse-on time (Ton), pulse-off time (Toff), amplitude of vibration (A), and pressure (p). Machining time was recorded from machine display unit for calculating cutting velocity

Figure 1. UCDWEDM setup (a) schematic diagram and (b) pictorial view. Note: UCDWEDM, ultrasonic-agitated concentric dry wire electric discharge machining.

Table 2. Experimental control parameters and its levels. Parameter Current (A) Pulse-on time (µs) Pulse-off time (µs) Amplitude (%) Pressure (kg/cm2)

Levels 3, 4, 5, 6, 7 24, 32, 40, 48,56 7, 9, 11, 13, 15 60, 70, 80, 90, 100 1, 1.5, 2, 2.5, 3

Table 3. Constants parameters and its values. Parameter Values Wire material 0.18 mm diameter molybdenum Work piece material 1.2 mm thick Ti–6Al–4V sheet Wire winding speed 10.5 m/s Machining length 25 mm for each cut Nozzle material Acrylonitrile butadiene styrene Nozzle hole 2 mm diameter hole Nozzle tip distance 1 mm

(CV) for the length of 25 mm. Measurement of surface roughness (SR) and Kerf width were performed after experiments.

Results and Discussion Table 1. Work material composition. Element C Al Composition (%)

0.013

5.524

V

Fe

Ti

3.539

0.141

90.783

Comparative investigation contributes understanding and analyzing performance improvement for UCDWEDM over USDWEDM. It has been observed from the literature that

MATERIALS AND MANUFACTURING PROCESSES

3

SR is termed as average roughness of the surface generated and lower value of SR is desirable for increased surface characteristics. KW is kerf width in mm. It is associated with the geometrical accuracy of profiles generated. Lower KW indicates better geometrical and dimensional accuracy.


Influence of pressure on CV, SR, and KW

Figure 2. Conceptual pictures of (a) USDWEDM and (b) UCDWEDM. Note: UCDWEDM, ultrasonic-agitated concentric dry wire electric discharge machining; USDWEDM, ultrasonic-agitated side dry wire electric discharge machining.

DWEDM experimented with side flow flushing similar to as shown in Fig. 2a. The proposed concept and mechanism of the process in concentric flow flushing is shown in Fig. 2b. Concentric or axial flow of gaseous dielectric media surrounds the wire from all over, which tend to improve the sparking cycles by promoting uniform wire wear. Compared with side flow in DWEDM, the concentric flow pattern of air jet is helpful to enhance flushing by direct jet impact on debris, better debris evacuation, avoid wire electrode vibration, and improve process stability. The following section represents influence of individual control variables over response variables. CV is length of cut per machining time, and it impacts on production economics.

Figure 3. Influence of pressure on (a) CV, (b) SR, and (c) KW.

Fig. 3a shows effect of air pressure on cutting velocity (CV). The response trend of CV in the UCDWEDM process is found similar to that reported for USDWEDM.[16] At initial levels, increased air pressure tends to improve debris flushing efficiency by effectively evacuating molten debris from the spark gap and prevents inactive pulses such as short circuit, hence CV increases correspondingly. However, with further increase of air pressure which results in more air in spark gap, so it may leads to expansion of plasma channel and lower discharge energy density, which in turn would have reduced cutting velocity.[17] Concentric flow resulted in higher CV than side flow system. Concentric flow pattern compared to side flow would have generated uniform flow streams with localized vortexes due to ultrasonic vibrations. That would have minimized the chances of resolidification of the molten debris on the work as well as wire surface and might have resulted into increased debris evacuation tendency and hence higher CV.[18–20] Fig. 3b indicates the response trend of SR for variation of air pressure. Results show that with increase of air pressure, SR decreased. This behavior is attributed to reason that with the increase in gas pressure, the number of damaging discharges, i.e., arcing, tend to decrease because of effective debris evacuation from the spark gap. In addition, effective debris evacuation in case of concentric flow would have resulted into minimum chances of debris reattachment on the work surface, and therefore, it produced lower SR.[17] The higher SR in side flow pattern might be due to the higher number of short circuiting resulted from more fluctuating spark gap by inclined air jet. Fig. 3c illustrates behavior of Kerf width (KW) for variation of air pressure. The trend reveals that with an increase in air pressure, KW increased gradually. The reason for such behavior could be answered as higher-pressure air results in higher

4

B. C. KHATRI ET AL


Figure 4. Influence of amplitude on (a) CV, (b) SR, and (c) KW.

amount of air in spark gap which leads to expansion of plasma. Expanded plasma channel resulted in widened KW.[17]

Influence of amplitude on CV, SR, and KW Fig. 4a illustrates behavior of CV for variation of amplitude. It is seen that with increase in amplitude of ultrasonic vibrations, CV increased for both processes UCDWEDM and USDWEDM similar to ultrasonic-agitated WEDM process.[21] The longitudinal ultrasonic waves of higher amplitude work similar to pump which sucks and expels debris from spark gap. The inertia effect and pumping characteristics of ultrasonic waves improves flushing of debris, and decreases short circuit occurs and result into improved CV. Moreover, the higher vibrational amplitude contributes to better ionization of spark gap by breaking molecules into ions due to the high impact energy of vibration.[21] Average CV resulted for UCDWEDM is 48% higher than USDWEDM, which is due to better process stability achieved by uniform flow in spark gap in case of concentric flow around the wire.[22] Behavior of SR for both side and concentric flow approaches under the influence of change in amplitude is represented in Fig. 4b. For increase in the amplitude of vibrations, the SR

Figure 5. Influence of current on (a) CV, (b) SR, and (c) KW.

decreased initially, and increased thereon. The behavior is answered as with increase in amplitude, ultrasonic waves help in evacuation of molten particles from spark gap. Hence, minimum adherence or resolidification of molten particles on the surface results into decreased SR. For amplitude more than 38 µm, SR increased due to unstable sparking and short circuit by high amplitude vibrating wire.[17] UCDWEDM produced 23% lower SR compared to USDWEDM. Fig. 4c indicates the response of KW for variation of amplitude. With increase in amplitude of vibrations, KW increased for both the approaches. It is due to the fact that increased pumping of debris from sparking gap may reduce the gap between wire and workpiece which in turn might have produced sparks, leading to higher KW.[17] Average KW obtained using UCDWEDM is 11% lower compared to USDWEDM, which is because of reduced wire vibration due to concentric flow around the wire compared to inclined jet over wire in USDWEDM process.

Influence of current on CV, SR, and KW Reponses of CV for both approaches by variation of current is presented in Fig. 5a. It is seen that CV increased with



increase in current. It is due to the fact that high amount of thermal energy transferred to sparking gap increased material removal. The results confirm that CV is influenced dominantly by current compare to other parameters.[23] Average relative performance obtained for UCDWEDM was 34% higher than USDWEDM. The resulted higher CV may be due to concentric flow of air and ultrasonic vibration, which could effectively cleanse debris generated in the spark gap at higher current. Fig. 5b illustrates the behavior of SR for variation of current. For any increase in current, SR increased for both processes as, such as WEDM process. Because of the higher current in discharge gap, it leads to higher energy transfer from wire to workpiece which increase the crater depth and volume. Deeper crater due to higher current leads to the coarser surface.[16] Also, UCDWEDM resulted in approximately 23% lower SR compared to USDWEDM. The lower SR value is because of concentric flow of air which might have prevented attachment of molten material on work surfaces. Fig. 5c indicates the response of KW by variation of current. It is seen that for rise in current, KW increases. Higher current dissipates more thermal energy, hence widening of gap results in higher KW. Average KW for UCDWEDM is 8% lower than USDWEDM. Side jet tend to vibrate wire more compare to concentric flow air jet. Hence, resulted higher KW compared with UCDWEDM.[18] Influence of Ton on CV, SR, and KW Fig. 6a demonstrates CV trend for selected range of Ton. For initial range of Ton, CV increased steeply. With increase in Ton, longer sparks are generated and removes more material which resulted in increased CV. However, after Ton of 40 µs, less time is available to evacuate the debris from the sparking gap. So, presences of debris in the sparking gap tend to produce frequent short circuits and result into wastage of pulse energy. Reduced pulse energy decreases the CV.[23] It is noted that UCDWEDM resulted in 42% higher CV compared to USDWEDM. This is attributed to the reason that at same Ton, concentric flow in UCDWEDM removes debris more efficiently from spark gap.[23]

Figure 6. Influence of pulse-on time on (a) CV, (b) SR, and (c) KW.

5

Fig. 6b describes effect of Ton over the SR. As the Ton increases, more time for discharge is available and also high amount of energy produces deeper craters and higher SR.[24] It is noted that USDWEDM resulted in 22% lower SR. Lower SR produced with USDWEDM might be due to the reason that inclined air jet for SDWEDM produce abrupt spark pattern in spark gap and produce craters at various points, hence creates rougher surface.[25] Fig. 6c indicates the response of KW by variation of Ton. It is seen that with increase in Ton, KW decreases. For higher Ton, more discharge energy is available. Opposite impact force acts on the wire during every individual spark discharge occurrence and that leads to decrease of KW. Also, higher electrostatic force due to transferring more electrons through wire may lead the wire to be wound. Hence, KW decreases by increasing Ton.[16] Comparative results indicated that UCDWEDM generates 9% lower KW than USDWEDM. It is due to the uniform concentric flow of air around wire which might have produced negligible wire vibration, hence resulted in lower KW. Influence of Toff on CV, SR, and KW Reponses for CV of both processes for variation of Toff is presented in Fig. 7a. From trend analysis, it is clear that Toff adversely affects to CV. Higher Toff increases idle time, hence no arcing and material removal takes place and results in cleaning of spark gap by dielectric flushing.[23] UCDWEDM resulted 45% higher CV to USDWEDM. Comparative response analysis of the processes indicated that for any value of Toff, higher CV is reported for UCDWEDM, which may be attributed to concentric air flow removes debris effectively. Fig. 7b reveals trend that for higher Toff, SR decreased. Arcing at low Toff leads to higher SR. As Toff increases, increase in idle time for debris evacuation due to better flushing, results in reduction in SR.[24] Results indicated that UCDWEDM produced 20% lower SR than USDWEDM. These might have resulted due to higher detachment of debris from the work surface due to efficient flushing. Fig. 7c indicates the response of KW by variation of Toff and KW continually increases, with an increase in Toff.[17,21] It is due to the fact that more Toff permits better spark gap

6

B. C. KHATRI ET AL


Figure 7. Influence of pulse-off time on (a) CV (b) SR, and (c) KW.

Table 4. Summary of average performance comparison of UCDWEDM w.r.t. USDWEDM. Process Parameters CV SR KW UCDWEDM over USDWEDM

Pressure Amplitude Current Pulse-on time Pulse-off time

142 148.36 134.75 142.37 145.14

80.92 77.67 76.86 77.75 79.98

94.21 96.64 92 91.51 87.47

UCDWEDM, ultrasonic-agitated concentric dry wire electric discharge machining; USDWEDM, ultrasonic-agitated side dry Wire electric discharge machining.

flushing and prevents adherence molten material on the surface, so leads to increase of KW.[22] Results obtained for UCDWEDM is 12% lower than USDWEDM. This is attributed to the reason that at same Toff, higher KW in USDWEDM is due to wide and scattered air jet which tend to affect material removal from the work material sides. Table 4 highlights percentage change in response variable of UCDWEDM over USDWEDM. For example, the results are to be read as under the influence of pressure, CV obtained for UCDWEDM is 142% of USDWEDM process. Concentric flow resulted 42% higher CV. Similarly, other results are to be read accordingly.

Conclusion From this research, it is summarized that concentric flow dry WEDM process with ultrasonic agitation resulted in improved production rate by higher cutting velocity, produced improved surface finish due to lower surface roughness and increased dimensional and geometrical accuracies by lower Kerf width, compared to ultrasonically agitated side flow dry WEDM process. Some of the main outcomes during research are mentioned below. 1. The concentric flow pattern of dry air resulted in 42, 48, 34, 42, and 45% higher CV than side flow pattern under the influence of process variables viz. pressure, amplitude, current, Ton, and Toff, respectively. It indicates that higher production rate can be achieved using concentric flow pattern for the supply of dielectric for dry WEDM. 2. The concentric flow pattern of dry air resulted in 19, 22, 23, 22, and 20% lower SR than side flow pattern under the influence of process variables viz. pressure, amplitude,

current, Ton, and Toff, respectively. Lower SR is an indication of lesser roughness hence generates better surface finish, which promises better tribological performance of the surfaces generated by this process for dies and punches. 3. The concentric flow pattern of dry air resulted in 6, 4, 8, 9, and 13% lower KW than side flow pattern under the influence of process variables viz. pressure, amplitude, current, Ton, and Toff, respectively. Lower KW ensures better dimensional and geometrical accuracies of the profiles generated thereby affirm the better quality products with concentric flow dry WEDM. The novel idea of utilizing concentric flow pattern for dielectric supply for the dry WEDM process with ultrasonic portrays is practically feasible and technically viable alternative to the conventional side flow pattern in the dry WEDM process.

Funding The research project is financially supported by Gujarat Council for Science and Technology (GUJCOST) under MRP scheme (GUJCOST/ MRP/15-16/1048) with kind permission of Commissioner (Technical Education), Gujarat, India, for utilizing facilities for this research project.

Nomenclature WEDM DWEDM USDWEDM UCDWEDM MRR CV KW SR Ton Toff

wire electric discharge machining dry wire electric discharge machining ultrasonic-agitated side dry wire electric discharge machining ultrasonic-agitated concentric dry wire electric discharge machining material removal rate (mm3/min) cutting velocity (mm/min) Kerf width (mm) surface roughness (µm) pulse-on time (µs) pulse-off time (µs)

References [1] Li, L.; Li, Z. Y.; Wei, X. T.; Cheng, X. Machining Characteristics of Inconel 718 by Sinking-EDM and Wire-EDM. Mater. Manuf. Proc. 2015, 30(8), 968–973.



[2] Mandal, A.; Dixit, A. R.; Das, A. K.; Mandal, N. Modeling and Optimization of Machining Nimonic C-263 Super Alloy using Multi cut Strategy in WEDM. Mater. Manuf. Proc. 2016, 31(7), 860–868. [3] Azam, M.; Jahanzaib, M.; Abbasi, J. A.; Wasim, A. Modeling of Cutting Speed (CS) for HSLA Steel in Wire Electrical Discharge Machining (WEDM) Using Moly Wire. J. Chin. Inst. Eng. 2016, 39(7), 802–808. [4] Valaki, J. B.; Rathod, P.P. Investigating Feasibility through Performance Analysis of Green Dielectrics for Sustainable Electric Discharge Machining. Mater. Manuf. Proc. 2016, 31(4), 541–549. [5] Valaki, J. B.; Rathod, P. P.; Khatri, B. C. Environmental Impact, Personnel Health and Operational Safety Aspects of Electric Discharge Machining: A Review. Proc. Inst. Mech. Eng., Part B. 2015, 229(9), 1481–1491. [6] Furudate, C.; Kunieda, M. Study on Dry–WEDM. Proc. of 2nd Int. Conf. of MMSS’ 2000, 325–332. [7] Kunieda, M.; Furudate, C. High Precision Finish Cutting by Dry WEDM. CIRP Anals– Manuf. Technol. 2001, 50(1), 121–124. [8] Wang, T.; Zhang, X.; Zhao, X. Study on Finishing Cut with Dry WEDM. Mater. Sci. Forum 2006, 533, 273–276. [9] Takeuchi, H.; Kunieda, M. Relation Between Debris Concentration and Discharge Gap Width in EDM Process. Int. J. Electr. Mach. 2007, 12, 17–22. [10] Masuzawa, T.; Cui, X.; Taniguchi, N. Improved Jet Flushing for EDM. Annals CIRP 1992, 41(1), 239–242. [11] Fujimoto, T.; Okada, A.; Okamoto, Y.; Uno, Y. Optimization of Nozzle Flushing Method for Smooth Debris Exclusion in Wire EDM. Key Eng. Mater. 2012, 516, 73–78. [12] Okada, A.; Konishi, T.; Okamoto, Y.; Kurihara, H. Wire Breakage and Deflection Caused by Nozzle Jet Flushing in Wire EDM. CIRP Annals – Manuf. Technol. 2015, 64(1), 233–236. [13] Khatri, B. C.; Rathod, P. P.; Valaki, J.B. Ultrasonic Vibration – Assisted Electric Discharge Machining: A Research Review. Proc. Inst. Mech. Eng., Part B 2016, 230(2), 319–330. [14] Tang, L.; Du, Y.T. Multi-Objective Optimization of Green Electrical Discharge Machining Ti–6Al–4V in Tap Water Via Grey-Taguchi Method. Mater. Manuf. Proc. 2014, 29(5), 507–513.

7

[15] Kuriachen, B.; Mathew, J. Experimental Investigations into the Effects of Micro electric Discharge Milling Process Parameters on Processing Ti–6Al–4V. Mater. Manuf. Proc. 2015, 30(8), 983–990. [16] Shayan, A. V.; Afza, R. A.; Teimouri, R. Parametric Study Along with Selection of Optimal Solutions in Dry Wire Cut Machining of Cemented Tungsten Carbide (WC–Co). J. Manuf. Proc. 2013, 15(4), 644–658. [17] Teimouri, R.; Baseri, H. Experimental Study of Rotary Magnetic Field-Assisted Dry EDM With Ultrasonic Vibration of Workpiece. Int. J. Adv. Manuf. Technol. 2012, 67(5–8), 1371–1384. [18] Hoang, K. T.; Yang, S. H. Kerf Analysis and Control in Dry Micro– Wire Electrical Discharge Machining. Int. J. Adv. Manuf. Technol. 2015, 78(9–12), 1803–1812. [19] Shabgard, M. R.; Alenabi, H. Ultrasonic Assisted Electrical Discharge Machining of Ti–6Al–4V Alloy. Mater. Manuf. Proc. 2015, 30(8), 991–1000. [20] Zhang, Q. H.; Zhang, J. H.; Ren, S. F.; et al. Study on Technology of Ultrasonic Vibration Aided Electrical Discharge Machining in Gas. J. Mater. Proc. Technol. 2004, 149, 640–644. [21] Han, G.; Soo, S. L.; Aspinwall, D. K.; Bhaduri, D. Research on the Ultrasonic Assisted WEDM of Ti–6Al–4V. Adv. Mater. Res. 2013, 797, 315–319. [22] Ningsong, Q.; Xiaolong, F.; Wei, L.; Yongbin, Z.; Di, Z. Wire Electrochemical Machining with Axial Electrolyte Flushing for Titanium Alloy. Chin. J. Aeronautics. 2013, 26(1), 224–229. [23] Khatri, B. C.; Rathod, P. P. Experimental Analysis of Concentric flow Dry Wire Electric Discharge Machining (CDWEDM). Proceedings of RK University’s First International Conference on Research & Entrepreneurship Rajkot, India, 2016 Jan 5–6, 1288–1300. [24] Khan, M. A.; Rahman, M. M.; Kadirgama, K. An Experimental Investigation on Surface Finish in Die–Sinking EDM of Ti–5Al– 2.5Sn. Int. J. Adv. Manuf. Technol. 2015, 77(9–12), 1727–1740. [25] Chalisgaonkar, R.; Kumar, J. Process Capability Analysis and Optimization in WEDM of Commercially Pure Titanium. Procedia Eng. 2014, 97, 758–766.