DEVELOPMENT OF WIRE ELECTRICAL DISCHARGE TURNING SETUP AND ITS APPLICATION FOR FABRICATION OF PREFORMED FOR MICRO TOOL

NAME:-SUVENDU BANERJE ADM NO:-14MT000107

MANUFACTURING(M.TECH)

GUIDED BY:-DR.AMIT RAI DIXIT

OUTLINE:- INTRODUCTION LITERATURE REVIEW  OBJECTIVES  EXPERIMENTATION RESULT AND DISCUSIONS COCLUSIONS SCOPE FOR FUTURE WORK

INTRODUCTION- In WEDM process, the material is eroded ahead of the wire due to the

thermoelectric sparks generated between the work piece and the electrode. In this process the work piece experiences no mechanical stresses due to no direct contact between the work piece and the wire makes the process widely employed to cut the electrically conductive hard-to-cut material with irrespective of its hardness and strength .

Fig:-Concept of Wire Electrical Discharge Machining

Wire electrical discharge turning (turning with WEDM) is one of the emerging area, developed to generate cylindrical form on hard and difficult to cut super alloys such as Titanium and Nickel. In WEDT process the electrical discharge takes place between the traveling wire and the rotating work piece (a rotary axis is added to WEDM) to be machined. In this process the desired cylindrical forms can be obtained by controlling the electrically charged wire in X and Y directions to remove the unwanted work material.

FIG:- Concept of Wire Electrical Discharge Turning

LITERATURE REVIEWAuthor and Year of publication

Material Process parameters

Output parameters

Methodology Remarks

Dr Masuzaw 2000

Microelectrode tool

- - - Cylindrical pins - 5 µm in diameter machined

Qu et. al. 2001 a

Carbide and Brass (2D and cylindrical)

Wire feed rate, Part rotation speed

Spindle error analysis, MRR in 2D and CWEDT

Donaldson reversal principle for spindle error analysis

MRRWEDT>MRRWEDM

BrassMRR > Tungsten CarbideMRR

Qu et. al. 2001 b

Pulse On time, wire feed rate and part rotational speed

MRR for rough and good surface finish, Surface roughness

SEM for measuring surface roughness.

Higher RPM & slower Vf generated smaller pitch and lower RaAchieved Surface Roughness: 0.68 µm

Mohammadi et. al. 2007

Cemented steel

Power, Time Off, Voltage, Servo volt, Wire tension, wire speer, RPM

Surface roughness, Roundness

L18 (21×37) Taguchi standard orthogonal array

power has a significant effect on the surface roughnessThe effects of wire speed, power, and servo on roundness are more significant than time-off, voltage, wire tension, and rotational speed.

Author and Year of publication

Material Process parameters

Output parameters

Methodology Result

M J haddad et. al. 2009

AISI D3 Tool steel

Power, Voltage, Pulse off time, RPM

Surface roughness, Surface roundness, Recast layer.

Taguchi method, SEM for measuring surface integrity

Under High MRR – Recast layer 40-50 µm, HAZ 20-25 µmUnder low MRR – Recast layer 15-20 µm, HAZ 8-13 µmPower and Voltage

Naresh baki et. al. 2014

TI-6AL-4V Alloy

RPM, ToN, ToFF, Peak current, Wire feed, Servo volt

Surface roughness and MRR

DOE: Taguchi methodOptimization: Gray Relational analysis

Optimal combination: RPM 30, ToN 10 µs, ToFF 50 µs, Peak current 150A, Wire feed 3mm/min, Servo 90VSignificant Parameters: RPM, ToN and Servo.

Balamurali et. al. 2015

Stainless Steel 316

Gap volt, ToN, ToFF, Wire speed, RPM

MRR, Surface roughness

Taguchi method L27

Gap V decrease MRR increase Ra decrease, ToN increase MRR increase Ra increase, ToFF increase MRR increase Ra decrease, RPM increase MRR & Ra increase

OBJECTIVES:- To develop WIRE ELECTRICAL DISCHARGE TURNING

(WEDT) setup on conventional WEDM system.

Investigation of input parameters of WEDT on output response.

Application of WEDT for fabrication of preformed for micro

tool.

Development of preformed for MICRO ECM, MICRO EDM

EXPERIMENTATION:-

The experiments are conducted on a high precision 4- axis CNC

WEDM . The wire EDM machine was equipped with a rotary axis in order to

produce cylindrical forms. TUNGSTEN work piece of 1mm diameter with

6mm length was used to perform the turning experiments on WEDM

Conventional design:-

wire used – Zinc coated brass wire of 0.25 mm

Dielectric – Deionized water

Process parameters – Spindle rotation speed, Voltage, Depth of cut

Output parameter – Diameter Deviation, Surface Roughness, Surface Waviness

Design of experiment - Taguchi L9 (34)Orthogonal Array Design

MICRO EDM and MICRO ECM were done on the preformed tool

Fig:- Schematic Of WEDT Setup Fig:- Actual WEDT Setup

Fig:- WEDT Operation Fig:-Specimen After Cut

MACHINED SURFACE

Fig:-Workpiece After MICRO ECMFig:-MICRO ECM Operation

Fig:-MICRO EDM Operation Fig:-Workpiece After MICRO EDM

RESULTS AND DISCUSSION

L9 (34) Taguchi standard orthogonal array, factors and factor levels were selected for

determining optimal process setting conditions, significant factors, and their

interactions.

After performing the experiments successfully the work-pieces final diameter,

roughness value (Ra) and waviness (Wa) values were measured in optical microscope

After getting all the dimensions the diameter deviation (∆d) is being calculated by

using the following equation

∆d= (Theoretical diameter) – (Actual Diameter) =Dtheo - Dact

Theoretical diameter = (Blank Size) – (2* Depth of Cut)

Actual Diameter = The diameters taken along the machined surface

Diameter deviation = mean of ∆d

Sl

No.

Spindle

Rotational

Speed

(rpm)

Gap

Voltage

(V)

Depth

Of Cut

(mm)

Diameter

Deviation

(∆d)(μm)

Surface

Roughness

(Ra)(μm)

Surface

Waviness

(Wa)

(μm)

SNRA1 SNRA2 SNRA3

1 30 30 0.300 74.13 0.46 1.49 -37.3999 6.744843 -3.46373

2 30 50 0.325 39.77 0.98 1.97 -31.9911 0.175478 -5.88932

3 30 70 0.350 145.94 0.47 1.73 -43.2835 6.558043 -4.76092

4 400 30 0.325 158.68 1.35 2.27 -44.0104 -2.60668 -7.12052

5 400 50 0.350 56.7 0.72 2.47 -35.0717 2.85335 -7.85394

6 400 70 0.300 187.06 0.34 1.49 -45.4396 9.370422 -3.46373

7 770 30 0.350 37.955 0.75 2.8 -31.5854 2.498775 -8.94316

8 770 50 0.300 23.353 0.36 1.78 -27.3669 8.87395 -5.0084

9 770 70 0.325 212.845 0.3 1.29 -46.5613 10.45757 -2.21179

Table-Experimental Result

SNRA= Signal To Noise Ratio

ANALYSIS OF THE OUTPUT RESPONSES:-Diameter Deviation(∆d):- Surface Roughness (Ra):-

Surface Waviness (Wa):-

The result of the three tests which were performed in WEDT is given below:

Sl

No.

Spindle

Rotational

Speed

(rpm)

Gap

Voltage

(V)

Depth

Of

Cut

(mm)

Diameter

Deviation

(∆d) (μm)

Surface

Roughness

(Ra) (μm)

Surface

Waviness

(Wa) (μm)

∆d1 ∆d2 ∆d3 Ra1 Ra2 Ra3 Wa1 Wa2 Wa3

1 400 50 0.3 68.11 120.32 79.495 1.06 1.145 1.385 3.75 3.235 4.54

MICROSCOPIC IMAGES OF WEDT MACHINED SURFACES :-

Fig: Texture Surface Fig :3D Surface withTexture

MICRO EDM OPERATION

VOLTAGE

(V)

PULSE

WIDTH/

TON(μs)

SPEED

(rpm)

Final Diameter

Surface roughness (Ra)(μm)

Surface Waviness(Wa)(μm)

40 40 5000 294μm 1.3 μm 3.1μm.

MICROSCOPIC IMAGES

Fig: Texture Surface Fig: 3D Surface With Texture

VOLTAGE

(V)

FREQUENC

Y

(Hz)

PULSE

WIDTH

(TON)

DUTY Final Diameter(μm)

Surface Roughness(Ra)(μm)

Surface Waviness(Wa) (μm)

10 10000 10 10 140 0.36 1.6

MICRO ECM OPERATION

MICROSCOPIC IMAGES

Fig:Texture Surface Fig: 3D Surface with Texture

FESEM IMAGES OF WEDT MACHINED SUREFACE

FESEM IMAGES OF MICRO EDM MACHINED SURFACE

LENGTH WISE PORTION

TOP PORTION

FESEM IMAGES MICRO ECM MACHINED SURFACE

Fig : Length Wise Fig: Top Portion

DEPOSITED ELEMENTS AND THEIR COMPOSITIONElement Weight% Atomic%

W M 82.88 27.79

C K 4.90 25.13

O K 12.22 47.08

Element Weight% Atomic%W M 59.87 10.86C K 17.96 49.87O K 17.19 35.83Na K 1.15 1.67Cl K 1.14 1.07K K 0.45 0.38Th M 2.25 0.32

WEDT MACHINED SURFACE

BLANK SURFACE

Element Weight% Atomic%W M 27.18 2.96C K 30.54 50.97O K 31.74 39.76Na K 1.50 1.31Al K 2.65 1.97S K 0.21 0.13Cl K 1.27 0.72K K 1.29 0.66Ca K 0.47 0.24Ti K 2.76 1.15Fe K 0.39 0.14

Element Weight% Atomic%W M 68.14 15.14C K 16.51 56.14O K 9.92 25.32Na K 0.60 1.07Cl K 0.40 0.46K K 1.26 1.32Th M 3.17 0.56

MICRO EDM Machined Surface

MICRO ECM Machined Surface

COCLUSIONS

It was observed after MICRO EDM operation that the diameter of one of the preformed tool reduced only 30μm in 1hr 5 minutes.

It was observed after MICRO ECM operation that the diameter of one of the preformed tool reduced 150μm in 5 minutes

It was observed craters, spherical nodules, globules of debris ,coral reef and micro cracks in both machined surface of WEDT and MICRO EDM

Cracks are being generated due to thermal and tensile stress. The nature of the cracks is due to the deionized water

In the MICRO ECM machined surface all shallow craters, globules of debris, and pockmarks formed by entrapped gases escaping from the re-deposited material reduced to a great amount

SCOPE FOR FUTURE WORK

Diameter of the tool can also be reduced less than 100μm by using those combining techniques

The issues such as residual stress after machining with WEDT may be investigated.

The issue of eccentricity after machining with WEDT may be investigated on the existed WEDM setup

The research work could be further extended over a variety of exotic advanced materials.

The possible use of cryogenic treated wire electrode for machining of nonconductive and composite materials (Ceramic, fiberglass etc.) could also be investigated