Electric Discharge

Machining of Titanium AlloySAHIL DEV

10406EN016

MECHANICAL, IIT-BHU

Contents

Introduction

Electrical Discharge Machining

Why to use EDM

Metal Removal Mechanism

Experimental Procedure

Experimental Result

Conclusions

References

INTRODUCTION

Titanium alloys are widely used in many industrial and commercial

applications. Examples: aerospace, chemical, automotive, medical

and sporting goods

Ti-6Al-4V is the most common Titanium alloy

Difficult to machine with the use of traditional machining process.

High manufacturing cost

Poor surface finish

Electrical discharge machining is very efficient to machine such

alloy

What is EDM

Electrical Discharge Machining,

also known as Spark Machining,

Spark Erosion.

Used on hard metals.

Works with electrically

conductive materials.

Source: Ref. 1

PERFORMANCE MEASUREMENT

Material Removal Rate

Tool Wear Rate

Surface Quality

PROCESS PARAMETERS

Spark On-time

Spark Off-time

Discharge current

Electrode material

EXPERIMENTAL PROCEDURE:

Ti-6Al-4V ALLOY

Alpha + Beta alloy

Heat treatable

High strength

Low weight

High corrosion resistance

Used in aerospace industry

EXPERIMENTAL PROCEDURE

WORKPIECE MATERIAL PROPERTIES

Source: Ref. 1

ELECTRODE MATERIAL PROPERTIES

MACHINING CONDITION

Source: Ref. 1

EXPERIMENTAL RESULT: SURFACE

ROUGHNESS

Surface roughness increases with

increase in pulse current or pulse

duration.

Surface roughness improved at

extended pulse duration, i.e. 200µs

Aluminium electrode produces best

surface finish while graphite shows the

poorest.

Source: Ref. 1

WHITE LAYER THICKNESS

Exists due to the solidification

of the molten metal which is

not flashed away by the dielectric

White appearance observing

through the optical

microscope

Affects the hardness of

material

Source: Ref. 1

WHITE LAYER THICKNESS

Increases with the increase

in pulse current or duration

Thicker for graphite compare to the copper and

aluminium

Source: Ref. 1

MATERIAL REMOVAL RATE

Increases with the increase in

pulse current and pulse

duration.

But for extended pulse

duration i.e. 200µs MRR

decreases.

MRR is highest for the graphite

Source: Ref. 1

TOOL WEAR RATE

Increases with the increase in

pulse current and pulse

duration.

For aluminium tool wear rate is

the highest and MRR is the

lowest.

Source: Ref. 1

CONCLUSIONS

The material removal rate, surface roughness and electrode wear

are increasing with process parameters for each electrode material

except the prolonged pulse duration of 200µs.

The average white layer thickness is increasing with EDM parameters

REFERENCES

Ahmet Hascalık and Ulas Caydas, “Electrical discharge machining of titanium alloy (Ti–6Al–4V)” Applied Surface Science 253 (2007)

Mohammadreza Shabgard and Mirsadegh Seyedzavvar “Influence of Input Parameters on the Characteristics of the EDM Process” Strojniški vestnik - Journal of Mechanical Engineering 57(2011)

Serope Kalpakjian and Steven R Schmid, Manufacturing Engineering and Technology, Prentice Hall; 6th edition (27 Mar. 2009) Chapter 26: Advance Machining Process, Page no. 774.

www.sciencedirect.com/science/article/pii/S0169433207006988

http://en.wikipedia.org/wiki/Electrical_discharge_machining

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