Tr 00052

IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017

Available at: www.dbpublications.org

International e-Journal For Technology And Research-2017

Influence of Machine feed rate in WEDM with constant current (8A) using Brass wire on Titanium Ti-6Al-4V. Dr.T.Vijaya Babu1,a* , Dr .J.S Soni 2,b 1

Professor ,Department of Mechanical Engineering, Vardhaman College of Engineering , Shamshabad , Hyderabad, India

2,

Professor & Principal, Bharat Institute of Engineering and Technology , Ibrahimpatnam , Hyderabad, India a*

Abstract:

tirividhivijaybabu@gmail.com ,

Wire electrical discharge machining (WEDM) technology has been widely used in the field of medical, mould making, aerospace and automobile industries. It is a non-traditional machining process which used the continuously circulating wire as electrode and cuts the work piece along a programmed path. Improper electrical parameters settings can affect the processing efficiency and surface roughness due to arcing phenomenon that lead by discharge point of focus. Objective of the paper is to uncover the influence of two different machine rates which are 2 mm/min, 4 mm/min with constant current (8A) with WEDM of Titanium Ti-6Al-4V.The results on kerf width, material removal rate and surface roughness are graphically tabulated. The best combination of machining parameter viz. machine feed rate (4 mm/min), wire speed (8 m/min), wire tension (1.4kg) and voltage (60V) were identified. The selection of parameters depends on the requirements based on a better surface roughness or a maximum material removal rate. Hence an appropriate combination of variables can be selected accordingly.

Furthermore, this combination can contributes to increase production rates perceptibly by reducing machining time. The paper highlights the importance of process parameters and different machining conditions on kerf width, MRR, surface roughness (Ra) and surface topography.

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b

drjssoni@yahoo.com

Keywords: Wire Electrical

Discharge Machine

(WEDM),Surface Topography, Material Removal Rate(MRR) , Surface Roughness (SR).

1. INTRODUCTION Wire electrical discharge machining (WEDM) is broadly used in machining of materials when precision is of major factor. WEDM is an ideal means for manufacturing such tooling because its ability to cut any conductive material regardless of hardness. The productivity of fabricating micro tools can be increased with the use of WEDM technology where more intricate tool geometries can be created with high quality. Material is eroded by series of discrete sparks between the work piece and a tool electrode (small wire) immersed in a liquid dielectric medium (deionized water). These electrical discharges melt and vaporize diminutive amounts of the work material, which are then ejected and flushed away by the dielectric. Since, the work piece and the electrode do not have mechanical contact, conductive material regardless of their hardness

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International e-Journal For Technology And Research-2017 and toughness can be machined by WEDM . It

Brass wire is widely used in WEDM processes

consume a continuously travelling wire electrode

due to its good machining properties and can be die-

made of thin brass, copper or coated wire of

casted or extruded for specialized application. The

diameter 0.05–0.3mm

which is capable to

ideal wire electrode material for this process has three

achieve very small corner radii and competency to

important criteria i.e high electrical conductivity,

machine precise, complex and irregular shape

sufficient mechanical strength and optimum sparks

with high degree of accuracy and fine surface

and flushes characteristics.

finish. Titanium Ti-6Al-4V has become very

Dielectric

popular materials and widely used as implants for

Work pieces that are totally submerged in a tank

dental, restorations and orthodontic wires, as well

filled

as orthopedic due to their low density, high

stabilization and efficient flushing especially when the

corrosion resistance and excellent mechanical

work piece has varying thickness in WEDM process .

properties. However these alloys were very

WEDM used deionised water instead of hydrocarbon

difficult to fabricate as they are not ductile and

oil as the dielectric fluid due to its low viscosity and

have low fracture toughness at room temperature .

rapid cooling rate .

The paper focused on the importance of kerf

with

dielectric

fluid

grants

temperature

Parameter Setting

width, MRR, surface roughness (Ra) and surface

The experiment were performed at three different

topography and their strong dependence on the

machine feed rate with constant current, wire speed,

input parameters carried out on Titanium Ti-6Al-

wire tension and voltage as shown in Table 1.

4V. Parameter

Materials and Methods Work material

Machine feed

Titanium Ti-6Al-4V has enormous importance in the aerospace industries. It reduces aircraft weight since the excellent strength-to-weight ratio and causes a reduction

in

fuel

consumption

and

emissions.

Titanium is replacing aluminum in many applications .Titanium alloys are among the hardest materials to cut because of poor thermal conductivity, strength at high

Experime

Experimen

Experimen

nt 1

t2

t3

2

4

6

8

8

8

8

8

8

1.4

1.4

1.4

60

60

60

rate(mm/min) Current (A) Wire speed (m/min) Wire tension (Kg) Voltage (V)

temperatures and chemical reactivity with tool Table 1 Parameter setting

materials.

Wire electrode IDL - International Digital Library

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International e-Journal For Technology And Research-2017 Sample Preparation and Experimental Procedure All specimens were cleaned in an alcohol bath and then dried specimen Dryer in blower mode. After that, the specimens were kept in Buehler Specimen Cabinet Storage to prevent the formation of oxide on the surface. Titanium Ti-6Al-4V work pieces are cut into the desired size using Wirecut EDM Mitsubishi Machine in the presence of dielectric fluid

with

addition of anti rust agent liquid to reduce the surface rust. The kerf is measured the sum of the wire diameter and twice wire–work piece gap. The kerf value was expressed in three different spot and each spot will give ten readings, the average of these Fig 1: Pictorial view of WEDM machine tool

reading will be taken as kerf width. The material removal rate (MRR) will be calculated using equation

Result and Discussions

(1) this equation.

Kerf width MRR = FX D w X H

(1)

The lowest value of machine feed rate give smallest kerf width. Meanwhile, it can be seen clearly that

F is the machine feed rate [mm/min], Dw is wire diameter [mm] and H is piecework thickness [mm] and MRR is material removal rate [mm3 /min].

medium setting of machine feed rate gives the average value of kerf width and high setting of machine feed rate applied offered the widest value of kerf width.

KERFWIDTH

F is the machine feed rate [mm/min], Dw is wire diameter [mm] and H is piecework thickness [mm]

1.95 kerf width(mm)

and MRR is material removal rate [mm3 /min].

1.9

1.93 1.9 1.88

1.85

1.85

1.8 1

2

3

4

Machine feed rate (mm/min)

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International e-Journal For Technology And Research-2017 Fig 2: Result on kerf width of different machine feed

SR Surface roughnesµs ( µm)

rate Material Removal Rate (MRR) It was found that with the increasing of machine feed rate, the MRR will increases simultaneously . From the examination of the contour plot, it is noticed that MRR

increases

with

increase

in

feed

rate.

Theoretically, material erosion is influenced by the

1.94 1.92

1.93

1.9 1.9

1.88

1.88

1.86 1.84

1.85

SR

1.82 1.8 1

spark energy. As feed rate increase; MRR also increases till it reaches optimum. The MRR decreased

2

3

4

Machine feed rate (mm/min)

with the decreasing of machine feed rate.

Fig 4: Result on Surface roughness of different

material removal rate (mm3/min)

MRR 10 8 6 4 2 0 MRF

machine feed rate 8

Surface Topography

6 4

There are many factors which make machined surface

2 MRF 1

2

3

4

2

4

6

8

Machine feed rate(mm/min)

topography have the characteristics of complex and irregular, and impact using performance of parts due to its complicated process. The surface topography of each

experiment

under microscope

with 100×

magnification. It shows that low machine feed rate gives bigger crater compared to high feed rate and

Fig 3: Result on mrr at different machine feed rate

vice versa.

Surface Roughness (R a) Surface roughness (Ra) is an element in measuring surface quality. It is one of the important factor in machining because it can predict the performance.

Fig.4 enlightens that smoother surface can be obtained with low setting of machine feed rate.

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IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017

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International e-Journal For Technology And Research-2017 2mm/min

Machining (WEDM). Int J Mach Tools Manufacturing 44:1247–1259 [2] D. Rakwal and E. Bamberg, 2009, Slicing, Cleaning and Kerf Analysis of Germanium Wafers Machined by Wire Electrical Discharge Machining.

Mater. Process. Technol. 209(8), p 3740–3751 [3] Sadiq MA, Rahman M, Lim HS, 2008, Study of WEDM parameter phenomena for micro fabrication.

Int J Manuf Technol Manag 13(2–4):226–240 [4] Miller SF, Kao C-C, Shih AJ, Qu J., 2005,

4mm/min Fig 5: Topography view of different machine feed rate

CONCLUSION

Investigation of wire electrical discharge machining of thin cross-sections and compliant mechanisms. Int J Mach Tools Manuf 45:1717–1725 [5] Qu AJ Shih, RO S., 2002, Development of the cylindrical

wire

electrical

discharge

machining

In this paper, an effort was made to determine the

process: part І: concept, design and material removal

important machining parameters for the performance

rate. ASME J Manuf Sci Eng 124(3):702–707

of WEDM viz.kerf width, MRR and SR. The main

[6] Qu AJ Shih, RO S., 2002, Development of the

goal is the maximum MRR with the minimum kerf

cylindrical

and surface roughness in setting the machining

process: part ІІ: surface integrity and roundness. J

parameters. Factors machine feed rate have been found

Manuf Sci Eng 124(4):708–714 [7] Bradley, E.F.,

to play an important role in this experimental work.

1988, Super alloys: A technical guide, ASM

The outcome of this study will help in improving the

International.

quality of Titanium Ti-6Al-4V products as well as

[8] Ezugwu, E.O., Da Silva, R.B., Bonney, J.,

minimizing the machining cost to realize the

Machado, A.R., 2005, Evaluation of the performance

economical potential to the fullest.

of CBN tools when turning Ti–6Al–4V alloy with

wire

electrical

discharge

machining

high pressure coolant supplies, International Journal of Machine Tools and Manufacture, Vol. 45, pp. 1009-

REFERENCES

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2004, State Of The Art In Wire Electrical Discharge

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IDL - International Digital Library Of Technology & Research Volume 1, Issue 5, May 2017

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International e-Journal For Technology And Research-2017 [10] G. LĂźtjering, J.C. Williams, 2007, Titanium.

Springer [11] P. Kovacs, J. A. Davidson, in: S. A. Brown, J. E. Lemons (Eds.)., 1996, Medical Applications of Titanium and its Alloys: The Materials and Biological Issues, ASTM, STP 1272 pp. 163-178.

[12] B. Pan, D.J. Kim, B.M. Kim, T.A. Dean, 2001, Incremental deformation and the forgeability of titanium aluminide, Int. J. Mach. Tools Manuf. 41 749–759.

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