ppt on project work

44
ANNAMACHARYA INSTITUTE OF TECHNOLOGY &SCIENCES (Approved by A.I.C.T.E, New Delhi, Affiliated to JNT University, Anantapur) Tirupati, Chittoor Dist. (A.P)

Upload: chaitanya-poguri

Post on 22-Jan-2018

130 views

Category:

Documents


1 download

TRANSCRIPT

Page 1: ppt on project work

ANNAMACHARYA INSTITUTE

OF TECHNOLOGY &SCIENCES

(Approved by A.I.C.T.E, New Delhi, Affiliated to JNT University, Anantapur)

Tirupati, Chittoor Dist. (A.P)

Page 2: ppt on project work

EXPERIMENTAL INVESTIGATION ON

EFFECTS OF CUTTING PARAMETERS ON

MRR IN WIRE-EDM PROCESS

(INCONEL- 825)

Page 3: ppt on project work

Submitted by

P.CHAITANYA 12AK1A0309

P.LEELA SAGAR 12AK1A0326

K.KARTHEEK 12AK1A0322

K.BALAJI 12AK1A0305

S.RAHULSRINIVAS 12AK1A0343

Page 4: ppt on project work

Under the esteemed guidance of

Mr. M.MARUTHI RAO,

M .Tech, ( Ph. D)

Assistant professor,

Department of Mechanical Engineering

Page 5: ppt on project work

ABSTRACT

Wire Electrical Discharge Machining (WEDM) is one of the important

non- traditional machining processes. The Wire Electrical Discharge

Machining plays an important role in manufacturing sectors especially

industries like aerospace, automobile and general engineering etc. Intricate

profiles used in bio medical applications can also be done in WEDM .

INCONEL-825 is a nickel-based high-temperature strength super alloy

found applications in aerospace, missile, nuclear power, chemical and petro

chemical, heat treatment, marine and space shuttle components. The

characteristics such as higher strain hardening tendency, high dynamic

shear strength and poor thermal diffusivity are the major causes of

difficulty in machining of this alloy. These, in turn , produce higher cutting

forces, highly strain hardened and toughened chips and cause surface

damages extending to subsurface levels. All these effects, in general,

hamper the machinability of this alloy .owing to all these problems, it is

very difficult to machine INCONEL-825 by conventional machining

processes and moreover, by conventionally used tool materials.

Page 6: ppt on project work

• Hence the present work focused on optimization of process parameters in Wire Electrical Discharge Machining of Inconel-825 super alloy.In the present work, Taguchi's orthogonal array L27 .Each experiment was conducted under different conditions of input parameters is Pulse on Time, Pulse off Time, Flushing pressure Of Dielectric fluid, spark gap voltage, servo feed, Cutting speed.

• By using Minitab software by considering machining parameters: servo feed, servo voltage, cutting speed.

• The experiments were carried out on Inconel-825 Using ultra cut 843 CNC WEDM machine according to Taguchi experimental design . The experimental responses such as material removal rate(MRR) are recorded for experimental run. This experimental data is analysed using optimization methods : Taguchi method for process parameters optimization. The confirmation results of obtained optimum parameter combinations are evaluated and the best combination is selected. With this best combination , the goal of maximization of material removal rate (MRR) is achieved.

Page 7: ppt on project work

• W I R E E L E C T R I C A L D I S C H A R G E M A C H I N I N G ( W E D M ) I S O N E O F T H E M O S T I M P O RTA N T N O N - T R A D I T I O N A L M A C H I N I N G P R O C E S S E S .

• H E N C E , N O N - T R A D I T I O N A L M A C H I N I N G M E T H O D S I N C L U D I N G E L E C T R O C H E M I C A L M A C H I N I N G , U LT R A S O N I C M A C H I N I N G , E L E C T R I C A L D I S C H A R G I N G M A C H I N I N G ( E D M ) E T C . A R E A P P L I E D T O M A C H I N E S U C H D I F F I C U LT T O M A C H I N E M AT E R I A L S .

• W I R E E L E C T R I C A L D I S C H A R G E M A C H I N I N G ( W E D M ) P R O C E S S W I T H A T H I N W I R E A S A N E L E C T R O D E T R A N S F O R M S E L E C T R I C A L E N E R G Y T O T H E R M A L E N E R G Y F O R C U T T I N G M AT E R I A L S . W I T H T H I S P R O C E S S , A L L O Y S T E E L , C O N D U C T I V E C E R A M I C S A N D A E R O S PA C E M AT E R I A L S C A N B E M A C H I N E D I R R E S P E C T I V E O F T H E I R H A R D N E S S A N D T O U G H N E S S .

• F U RT H E R M O R E , W E D M I S A C A PA B L E O F P R O D U C I N G A F I N E , P R E C I S E , C O R R O S I O N A N D W E A R R E S I S TA N T S U R FA C E .

•. H O W E V E R , W E D M U T I L I Z E S A C O N T I N U O U S LY T R AV E L L I N G W I R E E L E C T R O D E M A D E O F T H I N C O P P E R , B R A S S O R T U N G S T E N O F D I A M E T E R 0 . 0 5 - 0 . 3 0 M M , W H I C H I S C A PA B L E O F A C H I E V I N G V E RY S M A L L C O R N E R R A D I I .

• T H E W I R E I S K E P T I N T E N S I O N U S I N G A M E C H A N I C A L T E N S I O N I N G D E V I C E R E D U C I N G T H E T E N D E N C Y O F P R O D U C I N G I N A C C U R AT E PA RT S . D U R I N G T H E W E D M P R O C E S S , T H E M AT E R I A L I S E R O D E D A H E A D O F T H E W I R E A N D T H E R E I S N O D I R E C T C O N TA C T B E T W E E N T H E W O R K P I E C E A N D T H E W I R E , E L I M I N AT I N G T H E M E C H A N I C A L S T R E S S E S D U R I N G M A C H I N I N G .

Introduction

Page 8: ppt on project work

Schematic diagram of the basic principle

of WEDM process

Page 9: ppt on project work

BASIC PRINCIPLE OF WEDM PROCESS

The main table moves along X and Y axes and it is driven

by the D. C servo motors.

The travelling wire is continuously fed from wire feed

spool and collected on take up spool which moves

through the work piece and is supported under tension

between a pair of wire guides located at the opposite sides

of the work piece.

The lower wire guide is stationary and moves according

to the upper wire guide.

Page 10: ppt on project work

BASIC PRINCIPLE OF WEDM PROCESS

A series of electrical pulses generated by the pulse

generator unit is applied between the work piece and the

travelling wire electrode, to cause the electro erosion of

the work piece material.

While the machining operation is continuous, the

machining zone is continuously flushed with water

passing through the nozzle on both sides of work piece.

Page 11: ppt on project work

Pictorial View of WEDM Machine Tool

Page 12: ppt on project work

History of WEDM

In 1969, the SWISS FIRM 'AGIE' produced the world's first WEDM, the process was fairly simple, not complicated and wire choices were limited to copper and brass only.

Early WEDM produced were extremely slow but as more and more research was done WEDM, cutting speed and overall capabilities of WEDM have been modified. In the early 70's a typical machine cut 2 square inches per hour (i. e. 21mm/min, in the early 80's, 6 square inches per hour (i. e.64mm2/min), however WEDM which are under operation today can cut 20 times faster than these earlier machines.

In recent years, the technology of WEDM has been improved significantly to meet the requirements in various manufacturing need, especially in the precision mold and die industry

. WEDM has greatly improved in terms of accuracy, quality, productivity and precision, thus immensely helped the tooling and manufacturing industry. WEDN=M operated in industry today are equipped with Computer Numerical Control (CNC) which helps in improving efficiency and accuracy[103]

Page 13: ppt on project work

WEDM Cutting gap

Page 14: ppt on project work

Importance of WEDM in industry

Wire Electrical Discharge Machining (WEDM) technology has grown tremendously since it was first applied more than 30 years ago. IN 1974, D.H. Dulebohnapplied the optical-line follower system to automatically control the shape of the components to be machined by the WEDM process.

By 1975,its popularity rapidly increased, as the process and its capabilities were better understood by the industry. It was only towards the end of the 1970s, when Computer Numerical Control (CNC) system was initiated into WEDM. which brought about a major evolution of the machining process (Ho et. al., 2004).

Page 15: ppt on project work

Features of WEDM

Multi pass facility (Up to 60-70mm height in punch and up to 100-120mm height in cavity)

Can cut a minimum radius of 0.08mm.

Total connected power of machine is 1.5KVA.

Low running cost.

Paper filter not required. Reusable fine mesh filtering system provided.

Can cut up to 500mm height.

Soft water and soap gel is mixed and used as a coolant, which gives a good surface finish, anti- corrosive protection to the components as well as machine.

Easy maintenance.

Can obtain a surface finish of 1.25µRa in multi pass machine (under appropriate parameter setting and standard test conditions).

New programs can be entered while cutting previous program.

Auto centre find, auto edge find, auto shift off at wire breakage and auto stop at the end of job.

Page 16: ppt on project work

Major components of WEDM

Work Table

Types Of Wires

1. Copper

2. Brass wires

3. Coated Wires

4. Fine wires (Molybdenum and Tungsten)

Electric Discharge power unit

Dielectric fluid

Filtration

Page 17: ppt on project work

INPUT PARAMETERS

Pulse ON Time

Pulse OFF Time

Flushing Pressure of Dielectric fluid

Servo Feed

Spark Gap

Cutting speed

Page 18: ppt on project work

INPUT PROCESS PARAMETERS

Pulse ON time

During This time the voltage is applied across the

electrode

Pulse OFF time

During this time the voltage is absent during the part of

the cycle.

Page 19: ppt on project work

INPUT PROCESS PARAMETERS

Spark gap set voltage

This sets the gap voltage between the wire and the work

piece. Lowering this setting makes this gap smaller.

Wire Feed

Wire feed is the rate at which the wire-electrode travels

along the wire guide path and is fed continuously for

sparking.

Page 20: ppt on project work

INPUT PROCESS PARAMETERS

Wire Tension

Wire tension is the amount of tension on the wire as it is

driven through its cutting motions.

It determines how much the wire is to be stretched

between upper and lower guides.

Servo Feed Set Voltage

Pulse peak voltage setting is for selection of open gap

votage.

Page 21: ppt on project work

INPUT PROCESS PARAMETERS

Flushing Water Pressure

This is because the small particles created by the EDM

process must be removed from the work area, otherwise

double burning of these particles will occur and the

insulation properties of the dielectric are eliminated

resulting in unstable cutting.

Servo Feed

It decides the servo speed, it can vary in proportion with

the gap voltage or can be held constant while machining.

Page 22: ppt on project work

OUTPUT PARAMETERS

MATERIAL REMOVAL RATE (MRR)

SURFACE ROUGHNESS

DIMENSIONAL DEVIATION

GAP CURRENT

Page 23: ppt on project work

OUTPUT PROCESS PARAMETERS

Material Removal Rate

Surface Roughness

Dimensional Deviation

Material Removal Rate

For WEDM, MRR is a desirable characteristic and it

should be as high as possible to give least machine cycle

time leading to increased productivity.

Page 24: ppt on project work

OUTPUT PROCESS PARAMETERS

Surface Roughness

Irregularities in the surface may form nucleation sites for

cracks or corrosion. Roughness is the measure of the

texture of a surface

Dimensional Deviation

It has been found that spark gap is an important response

decides the accuracy of the machined component in

WEDM.

Page 25: ppt on project work

Chemical composition of Inconel-825

Page 26: ppt on project work

Properties of Inconel-825

Page 27: ppt on project work

Advantages of WEDM Process

As continuously travelling wire is used as the negative electrode fabrication is no required as in EDM.

There is no direct contact between the work piece and the wire, eliminating mechanical stressed during machining.

WEDM process can be applied to all electrically conducting materials and alloys irrespective of their melting points, hardness, toughness or brittleness.

Users can run their work pieces over night or over the weekend unattended

Page 28: ppt on project work

Disadvantages of WEDM Process

High capital cost is required for WEDM process.

There is a problem regarding the formation of recast layer.

WEDM process exhibits very slow cutting rate.

It is not applicable to very large work piece.

Page 29: ppt on project work

Preparation of specimens

Page 30: ppt on project work

OPTIMIZATION METHODS Taguchi's Method

The objective of the robust design is to find the controllable process parameter settings for which noise or variation has a minimal effect on the products functional characteristics.

It is to be noted that the aim is noted that the aim is not to find the parameter settings for the un controllable noise variables, but the controllable design variables. To attain this objective, the control parameters, also known as inner array variables, are mathematically varied as stipulated by the inner orthogonal array.

For each experiment of the inner array, a series of new experiments are conducted by varying the level settings of the uncontrollable noise variables. The level combinations of noise variables are done using the outer orthogonal array.

The influence of noise on the performance characteristics can be found using the S/N ratio. Where S is the standard deviation of the performance parameters for each inner array experiment and N is the total number of experiment in the outer orthogonal array.

This ratio indicates the functional variation due to noise. Using this result, it is possible to predict which control parameter settings will make the process insensitive to noise. Taguchi method focuses on robust design

Page 31: ppt on project work

APPLICATIONS OF ORTHOGONAL ARRAY

Taguchi's OA analysis is used to produce the best parameters for the optimum design process, With the least number of experiments

OA is usually applied in the design of engineering products, test and quality development ,and process development.

Page 32: ppt on project work

ADVANTAGES AND DISADVANTAGES OF ORTHOGONAL ARRAY

Conclusions valid over the entire region spanned by the control factors and their settings.

Large saving in the experiment effort.

Analysis is easy.

OA techniques are not applicable , such as a process involving influencing factors that vary in time and cannot be quantified exactly

Page 33: ppt on project work

PROCESS PARAMETERS AND LEVELS FOR WEDM

Page 34: ppt on project work

Experimental data and results for the response parameters material removal rate

Page 35: ppt on project work

Surface roughness Tester

Page 36: ppt on project work

Applications of WEDM Process

Medical

Dental

Optical

Jewellery industries

Automobiles

Aerospace

Page 37: ppt on project work

RESULTS AND DISCUSSIONSANLAYSIS OF TAGUCHI

signal to noise ratio:

Calculation of the S/N ratio depends on the experimental objective .

Taguchiʼs emphasis on minimizing deviation from target lead him to develop measures of the process output that incorporate both the location of the output as well as the variation. These measures are called signal to noise ratios.

The signal to noise ratio provides a measure of the impact of noise factors on performance. The larger the S/N, the more robust the product is against noise

Page 38: ppt on project work

Response table for signal to noise ratios

Page 39: ppt on project work

Response Table for Means

Page 40: ppt on project work

Normal probability plotResponse is MRR

Page 41: ppt on project work

CONCLUSIONS

The results obtained in this study lead to conclusions for machining of INCONEL-825 After conducting the experiments and analyzing the resulting data.

1. From the results obtained by experiment, the influence on the response parameter Metal Removal Rate (MRR) by cutting parameters like servo voltage, servo feed and cutting speed of cut

a: The speed of cut has the variable effect on the Metal removal rate , servo voltage and servo feed an approximate decreasing trend.

2. The design of experiments (DOE), Taguchi method is applied for optimization of cutting parameters and analysis of variance (ANOVA) is done and found that

a: The optima combination of process parameters for minimum Metal removal rate is obtained cutting speed 40 m/min, servo feed 2100 mm/min and servo voltage 20 v voltage.

Page 42: ppt on project work

3. ANOVA shows that the cutting speed has great influence for the response Metal Removal rate (MRR) and its percentage contribution to the metal removal rate is determined to be

4. Using the experimental data, a multi linear regression model is developed and the values obtained for the response MRR is compared with measured values. A graph was plotted between Regression predicted values and experimentally measured values and shows that the models are adequate without any violation of independence or constant assumption

FUTURE SCOPE OF THE WORK

The effect of tool vibration, Work piece toughness, cutting fluid, tool material ,and work material can be considered as they have great influence on Metal removal rate and cutting forces. so , including all those along with cutting speed, servo feed, servo voltage and surface roughness may be calculated

Page 43: ppt on project work

ANY QUERIES?

Page 44: ppt on project work

THANK YOU