DESIGN AND FABRICATION OF WORKING

MODEL OF ABRASIVE JET MACHINE

(University Roll No. 100237682133)

In partial fulfillment for the aw

MASTER OF TECHNOLOGY

MECHANICAL ENGINEERING

PTU REGIONAL CENTRE

D.A.V INSTITUTE OF EN

DESIGN AND FABRICATION OF WORKING

MODEL OF ABRASIVE JET MACHINE

A PROJECT REPORT

Submitted by

JITESH KUMAR

(University Roll No. 100237682133)

partial fulfillment for the award of the degree

of

MASTER OF TECHNOLOGY

IN

MECHANICAL ENGINEERING

At

PTU REGIONAL CENTRE

UTE OF ENGINEERING & TECHNOLOGY

JALANDHAR

DECEMBER 2012

1

DESIGN AND FABRICATION OF WORKING

MODEL OF ABRASIVE JET MACHINE

GINEERING & TECHNOLOGY

2

DECLARATION

I hereby declare that the project entitled “DESIGN AND FABRICATION OF

WORKING MODEL OF ABRASIVE JET MACHINE” submitted for the M

Tech. Degree is my original work and the project has not formed the basis for the

award of any degree, associate ship, fellowship or any other similar title.

Signature of the student

Place:

Date:

3

CERTIFICATE

This is to certify that the project entitled “DESIGN AND FABRICATION OF

WORKING MODEL OF ABRASIVE JET MACHINE” is the bonafide work

carried out by JITESH KUMAR, student of M Tech (Part-time), Punjab

Technical University, Jalandhar, during the year 2012, in partial fulfillment of the

requirements for the award of the Degree of Master of Mechanical Engineering

and that the project has not formed the basis for the award previously of any

degree, diploma associate ship, fellowship or any other similar title.

Signature of the Guide

Place:

Date:

4

AKNOWLEDGEMENT

I deem it a privilege to have been a student of Mechanical Engineering stream in

DAV Institute of Technology, Jalandhar. I take this opportunity to express my

gratitude to all those who motivated, encouraged and helped me in the project

work. I’m grateful to my supervisor, Mr. Gaurav Dhuria, for his kind support,

guidance and encouragement throughout the project work, also for introducing to

me this topic, which has been very interesting and has given us great insight to the

future work on this area. I would like to take the chance to express my appreciation

to HOD, Mechanical Department Dr. Amit Kohli to provide this opportunity.

Special thanks to other members of the department for being so supportive and

helpful in every possible way. I would like to express my appreciation to my

friends Mr. Lovepreet singh and Mr. Angrej Singh. Their continuous support gave

me the strength for pursuing my dream.

DAVIET Jalandhar Jitesh kumar

November 2012 Univ. Roll No. 100237682133

Department of Mechanical Engineering

DAVIET Jalandhar

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ABSTRACT

Abrasive Jet Machining (AJM) is the process of material removal from a work

piece by the application of a high speed stream of abrasive particles carried in a gas

or air medium from a nozzle. The material removal process is mainly by erosion.

The AJM will chiefly be used to cut shapes in hard and brittle materials like glass,

ceramics etc. the machine will be automated to have 3 axes travel. The different

components of AJM are Compressor, Vibrator, dehumidifier, Pressure Regulator,

and Dust filter, Nozzle, Pressure gauge etc. The different components are selected

after appropriate design calculations.

In this project, a model of the Abrasive Jet Machine is designed using available

hardware and software etc. taking into consideration of commercially available

components. Care has been taken to use less fabricated components rather than

directly procuring them, because, the lack of accuracy in fabricated components

would lead to a diminished performance of the machine.

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List of Figures

Fig. 1 Schematic layout of abrasive jet machine

Fig 2 Effect of process parameters on erosion rate

Fig 3 Crack propagation during abrasive cutting of glass

Fig. 4 Filter regulator unit

Fig. 5 Abrasive container

Fig. 6 Cam

Fig. 7 Vibration Assembly

Fig. 8 Cut section of Nozzle

Fig 9 Position of nozzle

List of Tables

Table 1 Characteristics of different variables

Table 2 Cost calculation

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Table of contents

CHAPTER No. TITLE PAGE No.

Title Page 1

Declaration of the student 2

Certificate of the Guide 3

Acknowledgement 4

Abstract 5

List of Figures and tables 6

1. CHAPTER ONE

1.1 Introduction 9

1.2 Equipments 9

1.3 Different variables in Abrasive jet machine. 12

1.4 Variable characteristics 13

1.5 Advantages 14

1.6 Limitations 14

1.7 Applications 15

2. CHAPTER TWO

2.1 Literature Review 16

8

3. CHAPTER THREE

Components and their design

3.1 Compressor 19

3.2 FR Unit 19

3.3 Vibrating Unit 21

(i) Abrasive container

(ii) Cam

(iii) Induction Motor

3.4 Nozzle 25

4. CHAPTER FOUR

4.1 Total Assembly 26

5. CHAPTER FIVE

5.1 Cost estimation 27

• CONCLUSION 28

• REFRENCES 29

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1. CHAPTER ONE

1.1 Introduction

Abrasive Jet Machining (AJM) is the removal of material from a workpiece by the application of

a high speed stream of abrasive particles carried in gas medium from a nozzle. The AJM process

differs from conventional sand blasting in that the abrasive is much finer and the process

parameters and cutting action are carefully controlled.

The process is used chiefly to cut intricate shapes in hard and brittle materials which are sensitive

to heat and have a tendency to chip easily. The process is also used for deburring and cleaning

operations. AJM is inherently free from chatter and vibration problems. The cutting action is

cool because the carrier gas serves as a coolant.

1.2 Equipments

A schematic layout of AJM is shown in Fig‐1. The filtered gas, supplied under pressure to the

mixing chamber containing the abrasive powder and vibrating at 50 c/s, entrains the abrasive

particle and is the passed into a connecting hose. This abrasive and gas mixture emerges from a

small nozzle at high velocity. The abrasive powder feed rate is controlled by the amplitude of

vibration of the mixing chamber. A pressure regulator controls the gas flow and pressure.

The nozzle is mounted on a fixture. Either the workpiece or the nozzle is moved by cams

pantograph or other suitable mechanisms to control the size and shape of the cut. Hand operation

is sometimes adequate to remove surface contaminations or in cutting where accuracy is not very

critical. Dust removal equipment is necessary to protect the environment. Commercial bench

mounted units including all controls, motion producing devices, and dust control equipment are

available.

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Fig. 1 Schematic layout of abrasive jet machine

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The major components are:

1. Air compressor.

2. Air filter.

3. Dehumidifier.

4. Pressure Gauge.

5. Pressure Regulator.

6. Vibrator or Mixer.

7. Nozzle.

8. Arrangement to hold the work piece.

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1.3 Different variables in Abrasive Jet Machine:

The variables that influence the rate of metal removal and accuracy of machining in this process

is:

1. Carrier gas

2. Types of abrasive

3. Size of abrasive grain

4. Velocity of abrasive jet

5. Flow rate of abrasive

6. Work material

7. Geometry, composition and material of nozzle

8. Nozzle work distance (stand off distance)

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1.4 Characteristics of different Variables:

Medium Air , CO2 ,N2

Abrasive SiC, Al2O3 (of size 20µ to 50µ )

Flow rate of abrasive 3 to 20 gram/min

Velocity 150 to 300 m/min

Pressure 2 to 8 kg/cm2

Nozzle size 0.40 to 0.80 mm

Material of nozzle Tungsten carbide, Sapphire

Nozzle life 12 to 300 hr

Stand off distance 0.25 to 15 mm (8mm generally)

Work material Non Metals like glass, ceramics,

and granites.

Metals and alloys of hard materials

like germanium, silicon etc

Application Drilling, cutting, cleaning

Table 1 Characteristics of different variables

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1.4 Advantages:

1. Low capital cost

2. Ability to cut intricate holes shape in materials of any hardness.

3. Ability to cut heat sensitive material without damage.

4. As no heat is generated in the process, no change in microstructure

1.5 Limitations:

1. Material removal rate is low and hence its application is limited.

2. Embedding of the abrasive in the work piece surface may occur while machining softer

material.

3. The abrasive material may accumulate at nozzle and fail the process if moisture is present in

the air.

4. It cannot be used to drill blind holes.

5. Occasional plugging of mixing tube: Usually caused by dirt or large particles in abrasive.

6. Wear, misalignment, and damage to the nozzle.

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1.6 Application:

The major application of Abrasive jet machining process is in the machining of essentially

brittle materials and heat sensitive materials like glass, quartz, sapphire, semiconductor

materials, mica and ceramics. It is also used in cutting slot, thin sections, countering, drilling, for

producing integrate shapes in hard and brittle materials. It is often used for cleaning and

polishing of plastics nylon and Teflon components. Delicate cleaning, such as removal of

smudges from antique documents, is also easily done with Abrasive jet machining.

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CHAPTER TWO

2.1 Literature survey:

The literature study of Abrasive Jet Machine reveals that the Machining process was started a

few decades ago. Till date there has been a through and detailed experiment and theoretical study on

the process. Most of the studies argue over the hydrodynamic characteristics of abrasive jets, hence

ascertaining the influence of all operational variables on the process effectiveness including abrasive

type, size and concentration, impact speed and angle of impingement. Other papers found new

problems concerning carrier gas typologies, nozzle shape, size and wear, jet velocity and pressure,

stand‐off‐distance (SOD), or nozzle‐tip‐distance (NTD). These papers express the overall process

performance in terms of material removal rate, geometrical tolerances and surface finishing of work

pieces, as well as in terms of nozzle wear rate. Finally, there are several significant and important

papers which focus on either leading process mechanisms in machining of both ductile and brittle

materials, or on the development of systematic experimental‐statistical approaches and artificial

neural networks to predict the relationship between the settings of operational variables and the

machining rate and accuracy in surface finishing.

(Ref‐9) The erosion of brittle materials by solid micro-particles is a complex process in

which material is removed from the target surface by brittle fractures. The rate of material

removal is one of the most important quantities for a machining process. Predictive mathematical

models for the erosion rates in micro-hole drilling and micro-channel cutting on glasses with an

abrasive air jet are developed. A dimensional analysis technique is used to formulate the models

as functions of the particle impact parameters, target material properties and the major process

parameters that are known to affect the erosion process of brittle materials. The effect of various

parameters like abrasive mass flow rate, air pressure and stand off distance on erosion rate is

shown by following graphical presentation.

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Fig 2 Effect of process parameters on erosion rate

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(Ref‐10) The AJM has been applied to rough working such as deburring and rough finishing. With

the increase of the needs for machining of ceramics, semiconductors, electronic devices and

LCD’s, micro-AJM has become a useful technique for micro machining. Experimental results

showed good performance in micro-grooving of glass; however, the size of machined groove

increased about 2–4 µm. With the fine-tuning the compensation for film wear, micro-AJM could

be effectively applied to the micro-machining of semiconductors, electronic devices and LCD.

The crack propagation during impact of abrasive particles on machining material is given below:

Fig 3 Crack propagation during abrasive cutting of glass

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CHAPTER THREE

Components and their design

3.1 Compressor

Compressor is a device that converts power (usually from an electric motor, a diesel engine

or a gasoline engine) into kinetic energy by compressing and pressurizing air or gas which can be

released according to use. In this project, a reciprocating air compressor of 2kW is used to

produce compressed air up to the pressure of 150 psi and having storage tank which has storage

capacity of 50 liters.

3.2 FR Unit (Dehumidifier):

The FRL Unit (Air Filter Regulator Lubricator unit) which is otherwise called the moisture

separator or dehumidifier is required for separating the moisture from air. Atmospheric air

always contains some water vapors in it. As the air with high velocity is blown from the nozzle

there is an abrupt rise in pressure which converts water vapors into moisture. The moisture

makes the abrasive particles to agglomerate and this clogs the outlet of the Nozzle. To avoid this

clogging moisture separator should be used before abrasive particles are mixed with compressed

air. Different FRL Units are available commercially.

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Fig. 4 Filter regulator unit

INLET

OUTLET

Circulation of air

Separation of moisture

21

3.3 The Vibrating Unit:

Vibrating Unit is used for mixing the air with the abrasive particles (Al2O3). The Abrasive

particles are stored in a container through which air is flown. The particles are agitated by means

of a cam and motor arrangement. The rotation of cam results in vibration in the abrasive

container. The flow rate of abrasive materials can be controlled by manipulating the rotational

speed of the motor. The abrasive container will have one inlet and one outlet for air passage and

will be vertically suspended from a hinged joint. So the Vibrating Unit consists of following

parts –

i. Abrasive container

ii. Cam

iii. Induction Motor

(i) Abrasive container

Fig. 5 Abrasive container

Outlet

Inlet

22

Abrasive container is fabricated by a hollow cylindrical thick metallic pipe of 60mm diameter

and 140mm height. Two circular pipes of internal diameter 18mm is dipped from the top and

welded, which would act as input for compressed air and output for mixture of compressed air

and abrasive particles. The length of input pipe dipped is kept long to uniform circulation of

compressed air into the container.

(ii) Cam

Cam is fixed with shaft of the induction motor. The profile of the cam is taken to be a

circular one. The distance between two centers as shown in fig‐26 is 5mm. When the motor

rotates; it makes the container to vibrate. Width of cam is 35mm.

Fig. 6 Cam

(iii) Induction Motor

Induction motor used in this project is Single phase AC Induction motor of 0.5 watt. This

motor is used to provide rotational motion to the Cam attached with it. The installed induction

motor has speed of 600 rpm.

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24

Fig. 7 Vibration Assembly

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3.4 Nozzle

A standard high carbon high chromium cylindrical rod was cut into required length by

power hack‐saw. The external diameter was then brought to 20mm by turning it in lathe and then

the tip was made by tapering one end by the same lathe. A blind hole of approximate depth

25mm was made on the planner face of the rod by means of a 12mm drill bit in a drilling

machine. The end of the blind hole forms a shape of 118 degree taper because of the tool tip

angle. Internal threading was made by 12mm tap. Then the tip of the nozzle is diameter drilled to

approximate diameter of 1mm

Fig. 8 Cut section of Nozzle Fig 9 Position of nozzle

Threaded

1 mm hole

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CHAPTER FOUR

4.1 Total assembly:

Finally all parts are assembled with hose pipes and clamps. First of all compressor is joined with

FR unit which is acting as filter, dehumidifier and regulator. Then further FR is attached with the

abrasive container with pipes. Then from the output of abrasive container a pipe is attached to

the nozzle which will help to transport compressed air and abrasive mixture to the nozzle. Along

with it Induction motor is also attached to the cam and this assembly is provided to abrasive

container as given in the picture below:

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CHAPTER FIVE

5.1 Cost calculation:

S No. Name of Item Quantity Cost per unit Total cost of item

1. Reciprocating Air

compressor

1 8000 8000

2. FR unit 1 1200 1200

3. Abrasive container 1 400 400

4. Induction Motor 1 900 900

5. Abrasives 3 kg 50 150

6. Accessories - 2000 2000

7. Other expences - 1500 1500

TOTAL 14150

Table 2 Cost calculation

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CONCLUSION

In this project a complete design of the Abrasive Jet Machine is given. The total assembly is

designed taking in account of currently available components in the market. The designing and

assembling of very large number of components was a tremendous task and was completed on

time. However because of some parts couldn’t be purchased the whole assembly was limited to

some basic manufacturing operation.

The project can go beyond its current position and capabilities by employing automation into it.

This can be done by using stepper motors or DC servo motors interfaced with standard PCI

controllers or standalone controllers. 2‐D profiles can be converted into standard G‐codes and

M‐codes and that can be sent to the machine to perform automated machining.

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BIBLIOGRAPHY AND REFERENCES

Books

1. “Modern machining processes” by P C Pandey & H S Shan, The McGraw-Hill

companies.

2. “Production Technology” by R K Jain, Khanna Publications.

3. “Production Technology”, HMT Publications.

Websites

4. www.science direct .com.

5. www.apex.com

6. www.indiastudychannel.com

7. www.youtube.com

8. www.indiamart.com

Journals

9. “Modeling of erosion rate in micro abrasive air jet machining of glasses” by J M Fan, C

Y Wang, J Wang. Faculty of Electromechanical Engineering, Guangdong University of

Technology, Guangzhou 510006, China

10. Journal of material processing technology, Volume 146, 28 February 2004,

Page 234-240