optimization of wedm process parameters using taguchi method

1

Raju Kumar (Roll no 1002061)

Dharam Deo Prasad (Roll no 1002062)

OPTIMIZATION OF WIRE ELECTRICAL DISCHARGE MACHINING PROCESS PARAMETERS USING TAGUCHI METHOD

Overview• Wire Electric Discharge Machining• Process Parameters • Taguchi Design of Experiments• Grey Based Taguchi Method of

Optimization

2

Sometimes it is referred to as spark machining, spark eroding, burning, die

sinking or wire erosion

Its a manufacturing process whereby a desired shape is obtained using

electrical discharges (sparks).

Material is removed from the workpiece by a series of rapidly recurring

current discharges between two electrodes, separated by a dielectric liquid and

subject to an electric voltage.

One of the electrodes – ‘tool-electrode’ or ‘tool’ or ‘electrode’.

Other electrode - workpiece-electrode or ‘workpiece’.

As distance between the two electrodes is reduced, the current intensity

becomes greater than the strength of the dielectric (at least in some points)

causing it to break.

ELECTRIC DISCHARGE MACHINING

Introduction

3

• EDM - System

ELECTRIC DISCHARGE MACHINING

4

Introduction

WIRE ELECTRIC DISCHARGE MACHINING

Also known as wire-cut EDM and wire cutting.

A thin single-strand metal wire (usually brass) is fed through the workpiece

submerged in a tank of dielectric fluid (typically deionized water).

Used to cut plates as thick as 300 mm and to make punches, tools, and dies

from hard metals that are difficult to machine with other methods.

Uses water as its dielectric fluid; its resistivity and other electrical properties

are controlled with filters and de-ionizer units.

The water flushes the cut debris away from the cutting zone.

Flushing is an important factor in determining the maximum feed rate for a

given material thickness.

Commonly used when low residual stresses are desired, because it does not

require high cutting forces for material removal.

5

WEDM - System



WEDM Components

-four major components

6

• Computerized Numerical Control (CNC) - The Brains.• Power Supply -The Muscle• Mechanical Section - The Body• Dielectric System -The Nourishment

7

ADVANTAGES


• Better stability and higher productivity .• Higher machining rate with desired accuracy and minimum

surface damage.• Uses in the production of forming tools.• To produce plastics moldings, die castings, forging dies etc.• Can be applied to all electrically conducting metals and alloys

irrespective of their melting points, hardness, toughness, or brittleness.

8

•Special form of EDM - uses a continuously moving conductive wire

electrode.

Material removal occurs as a result of spark erosion as the wire electrode is

fed, from a fresh wire spool, through the workpiece.

Horizontal movement of the worktable (CNC) determines the path of the cut.

Application - Machining of super hard materials like polycrystalline diamond

(PCD) and cubic boron nitride (CBN) blanks, and other composites.

Carbon fiber composites are widely used in aerospace, nuclear, automobile,

and chemical industries, but their conventional machining is difficult


Applications – Wire EDM

9

• Main Machining Parameters

MACHINING PROCESS PARAMETRS

Pulse-on time(μs)

Pulse-off time(μs)

Wire feed(mm/min)

Gap voltage(volt)

10

Orthogonal array

The Taguchi Approach to DOE

From every trial series we can obtain an average result level and a measure of the variation, si, i=1,2, … ,9. These values can then be used as a basis for choosing the combination of factor levels that provides the most robust design.

ControlFactors

EXP.NO

A B C D

1 1 1 1 1

2 1 2 1 2

3 1 3 3 3

4 2 1 2 3

5 2 2 3 1

6 2 3 1 2

7 3 1 3 2

8 3 2 1 3

9 3 3 2 1

11

The Taguchi Approach to DOE

symbol Control factor

Unit Level 1 Level 2 Level 3

A Pulse-on time

μs 4 6 8

B Pulse-off time

μs 4 6 8

C Wire feed

mm/min 2 4 6

D Gap voltage

volts 40 50 60

Process parameters & their levels

12

Two types of optimizing techniques

Optimizing Techniques using Taguchi method

1. Grey based Taguchi method 2. Fuzzy based Taguchi method

We have used grey based Taguchi method for optimizing machining parameters in wire EDM using LM6B4C composite material produced by stir casting .

Two types of LM6B4C Composite material was manufactured as workpiece for cutting by WEDM.•LM6 +5%B4C •LM6 +10%B4C

13

• widely used in different fields of engineering to optimize the process parameters.

• To solve the multiple performance characteristics problems , the Taguchi method is coupled with grey relational analysis.

• An OA provides a set of well-balanced experiments, and Taguchi’s signal-to-noise. (S/N) ratios, which are logarithmic functions of the desired output, serve as objective functions for optimization.

Grey based Taguchi method

Introduction

14

Procedure of the grey-based Taguchi method.


15

To find S/N ratios values


For MRR

And, For surface roughness and kerf width(k)

Where n = number of replications and yij = observed response value Where i=1, 2... ....n; j = 1, 2...k.

16

Further analysis & calculations


• find normalized S/N ratio values .• find grey relational coefficient .• find grey relational grade.• Draw graphs for Grey relational grades for maximum

MRR, Minimum Ra and minimum kerf width .• find optimum levels of the factors from the graphs & the

tables of experiments separately.• Compare both the optimal values obtained from the tables

& graphs.

17

RESULTS AND DISCUSSION


• Confirmation test for the optimal parameter setting was conducted.

• LM6 +10%B4C has the optimal value within the orthogonal array .

• LM6 +5%B4C the optimal value from the L9 orthogonal array is different from the optimal value obtained from the Grey theory design .

• Hence a conformation experiment is conducted to find the improvements in the process.

18



Conformation experiment for LM6 +5%B4C

Optimal process parameters

Orthogonal Array Grey theory Design

Level

A2B2C3D1

A2B1C3D1

MRR (g/min)

0.0612

0.0841

Time(sec)

2.13

1.55

Ra (μm) 3.26 3.79

Kerf(mm)

0.336 0410

19



The optimal process parameters based on Grey Relational Analysis

For Aluminium boron carbide (5%)

for Aluminium boron carbide (10%)

40 V Gap Voltage 40 V Gap Voltage

4 μs pulse on-time 4 μs pulse on-time

6 μs pulse off-time 4 μs pulse off-time

6 mm/minute Wire Feed rate

2 mm/minute Wire Feed rate

20

CONCLUSION


• The Material Removal Rate shows an increased value of 0.0612g/min to 0.0841g/min.

• The time shows a reduced value of 2.13 sec to 1.55 sec .

• Positive indicators of efficiency in the machining process.

21

THE END


THANK YOU

optimization of wedm process parameters using taguchi method

Business