ABRASIVE JET MACHINING

AND

STUDY OF PROCESS PARAMETERS

Abrasive Jet Machine

Introduction

Abrasive jet machining (AJM) is a non-traditional machining

process that can machine material without generating heat and

shock.

Abrasive jet machining (AJM) is commonly used for Cutting,

Cleaning, Drilling and Etching operation

Mechanism of AJM

•Fine particles are accelerated in

gas stream .

•The particles are directed towards

the focus of machining.

• As the particle impacts the surface,

it causes a small fracture, and the

gas stream carries both the

abrasive particles and the

fractured (wear) particles away.

Conventional

Abrasive Jet Machine

Compressor

Constructional Details

Equipments involved in the construction of the

“ Abrasive Jet Machine” are as follows

1. COMPRESSOR

2. VIBRATOR

3. MIXING CHAMBER

5. MACHINE TABLE

4. NOZZLE

6. PRESSURE GAUGE & REGULATOR

Process Parameters

1.Carrier Gas :Carbon dioxide, nitrogen & air. Air is most widely used

3.Velocity of abrasive :The jet velocity is a function of nozzle pressure & design.

The range of jet velocity is 150-300 m/min

4. Work Material :It is recommended for processing of brittle material

2.Abrasive :Aluminum oxide, Silicon carbide, Sodium bicarbonate etc.

5. Nozzle Tip Distance (NTD) :It is the distance between the nozzle tip & work material.

The variables that influence the rate of metal removal are as follows :

Effect of Process Parameters on

Machininga) Effect of Pressure of carrier gas on Material Removal Rate (MRR)

S.No. Gas Pressure

(Kgf/cm2)

Material Removal Rate (MRR)

(mg/min)

1 5 18

2 6 21

3 7 23

4 8 26

Source : Previous Experiments conducted by M. Roopa Rani and S. Seshan

0

5

10

15

20

25

30

1 2 3 4

Pressure (Kgf/cm2)

Mate

rial R

em

ov

al

Rate

(M

RR

),

mg

/min

Gas Pressure Kgf/cm2

Material Removal Rate

mg/min

Table a)1 : Effect of Pressure on MRR

Fig a)1 : Effect of Pressure on MRR

(b) Effect of Nozzle Tip Distance (NTD) on Diameter of Cut.

S. No. Nozzle Tip Distance

(NTD)

(mm)

Diameter of Cut

(mm)

1 0.79 0.46

2 5.00 0.64

3 10.01 1.5

4 14.99 2.01

Source : Previous Experiments conducted by M. Roopa Rani and S. Seshan

Table b1:Effect of Nozzle Tip Distance on Diameter of Cut.

Fig b1:Shows the effect of Nozzle Tip Distance on Diameter of Cut.

Block Diagram of

Fabricated Abrasive Jet Machine

Workpiece

Table

Nozzle Tip Distance

(NTD)

Nozzle

Mixing Chamber

Hopper

Regulating

ValveCompressor

Air

Abrasive Jet Machine

Photograph of

Fabricated Abrasive Jet Machine

Experimental Procedure:

Glass was used as a test specimen, was cut into square and

rectangular shape for machining on AJM.

Specimens were cleaned using air jet and weighed on a sensitive

scale, accurate to 0.001 gram .

Each test sample was placed on the work chamber and machined

by abrasive jet machine by varying various process parameters

The machine work piece was then removed, cleaned and

weighed again to determine the amount of material removed

from the work piece.

The size of hole at the top surface and bottom surface was

measured and the results were tabulated.

Experimental Details:

Experiment No:1- NTD Vs Diameter of Hole

Observation – 1.1

1 2 3 4NTD=6 NTD=12 NTD=15 NTD=18

Fig.1.1.1 Machined Work piece at Pressure = 5.5 kgf/cm2

Thickness of material = 4 mm

5.33

Observation Table

6.6511.65184

11.21153

5.058.72122

4.517.0561

Bottom Surface

Dia

(mm)

Top Surface

Dia

(mm)

Nozzle Tip Distance

NTD (mm)S.No.

Pressure = 5.5 Kgf/cm2

Table1.1 Effect of Nozzle Tip Distance on Dia of Hole.

Fig 1.1.2. Shows the graph of Diameter of Hole vs. Nozzle Tip Distance

6 8 10 12 14 16 18

4

5

6

7

8

9

10

11

12

NT

D (

mm

)

Diameter of hole (mm)

Top Surface Dia.

Bottom Surface Dia.

Dia

Of

Hole

(mm)

NTD (mm)

Graph

Experiment No:1- NTD Vs Diameter of Hole

Observation – 1.2

Fig 1.2.1 Machined Work piece at Pressure =6.5 kgf/cm2

Thickness of material = 4 mm

Observation Table

Pressure = 6.5 Kgf/cm2

S.No.Nozzle Tip Distance

NTD (mm)

Top Surface Dia

mm

Bottom Surface Dia

mm

1 6 7.55 4.55

2 12 9.75 5.65

3 15 11.15 5.91

4 18 11.75 6.05

Table1.2 Effect of Nozzle Tip Distance on Dia of Hole.

6 8 10 12 14 16 18

4

5

6

7

8

9

10

11

12

NT

D (

mm

)

Diameter of hole (mm)

Top Surface Dia.

Bottom Surface Dia.

NTD (mm)

Dia

Of

Hole

(mm)

Fig 1.2.2 Graph of Diameter of Hole vs. Nozzle Tip Distance

Graph

Fig 1.3.1 Machined Work piece at Pressure = 8 kgf/cm2

Thickness of material = 4 mm

Experiment No:1- NTD Vs Diameter of Hole

Observation – 1.3

Observation Table

Pressure = 8 Kgf/cm2

S.No.Nozzle Tip Distance

NTD (mm)

Top Surface Dia

mm

Bottom Surface Dia

mm

1 6 7.72 5.05

2 12 9.95 5.75

3 15 11.45 5.96

4 18 11.81 6.75

Table1.3 Effect of Nozzle Tip Distance on Dia of Hole

6 8 10 12 14 16 18

5

6

7

8

9

10

11

12

NT

D (

mm

)

Diameter of Hole (mm)

Top Surface Dia.

Bottom Surface Dia.

Dia

Of

Hole

(mm)

NTD (mm)

Graph

Fig1.3.2 Graph of Diameter of Hole vs. Nozzle Tip Distance

Experiment No:2- Pressure Vs Material Removal Rate (MRR)

Observation - 2.1

Fig 2.1.1 Machined work piece for determination of MRR at Pr.=5.5 kgf/cm2

Pressure 5.5 kgf/cm2 Initial weight = 140.190 gm

Final Weight = 140.150 gm Time = 20 sec

Thickness = 8mm MRR = 120 mg/min

Fig 2.1.2 Machined work piece for determination of MRR at Pr.=6.5 kgf/cm2

Pressure 6.5 kgf/cm2 Initial weight = 141.200 gm

Final Weight = 141.130 gm Time = 20 sec

Thickness = 8mm MRR = 210 mg/min

Fig.2.1.3 Machined work piece for determination of MRR at Pr.=7.5 kgf/cm2

Pressure 7.5 kgf/cm2 Initial weight = 137.530 gm

Final Weight = 137.370 gm Time = 20 sec

Thickness = 8mm MRR = 400 mg/min

Observation Table

S.No.

Thickness = 8 mm, NTD = 12 mm

Pressure

kgf/cm2

Initial Weight

(gm)

Final Weight

(gm)

Time

(sec)

MRR

(mg/min)

1 5.5 140.190 140.150 20 120

2 6.5 141.200 161.130 20 210

3 7.5 137.530 137.370 20 400

Table 2.1 Effect of Pressure on MRR

5.5 6.0 6.5 7.0 7.5

100

150

200

250

300

350

400

MR

R (

mg/m

in)

Pressure (Kgf/cm2)

Fig.2.1.4 Graph of Pressure vs. MRR

Graph

Experiment No:2- Pressure Vs Material Removal Rate (MRR)

Observation - 2.2

Fig. 2.2.1 Machined work piece for determination of MRR at Pr.=5.5 kgf/cm2

Pressure 5.5 kgf/cm2 Initial weight = 206.600gm

Weight = 206.570 gm Time = 20 sec

Thickness = 12 mm MRR = 90 mg/min

Fig.2.2.2 Machined work piece for determination of MRR at Pr.=6.5 kgf/cm2

Pressure 6.5 kgf/cm2 Initial weight = 207.130gm

Final Weight = 207.059 gm Time = 20 sec

Thickness = 12mm MRR = 213 mg/min

Fig 2.2.3 Machined work piece for determination of MRR at Pr.=7.5 kgf/cm2

Pressure 7.5 kgf/cm2 Initial weight = 201.750 gm

Final Weight = 201.590 gm Time = 20 sec

Thickness = 12mm MRR = 480mg/min

Observation Table

S.No.

Thickness = 12 mm, NTD = 12 mm

Pressure

kgf/cm2

Initial Weight

(gm)

Final Weight

(gm)

Time

(sec)

MRR

(mg/min)

1 5.5 206.600 206.570 20 90

2 6.5 207.130 207.059 20 213

3 7.5 201.750 201.590 20 480

Table.2.2 Effect of Pressure on MRR

Graph

5.5 6.0 6.5 7.0 7.5

50

100

150

200

250

300

350

400

450

500

550

MR

R m

g/m

in

Pressure Kgf/cm2

Fig.2.2.4 Graph of Pressure vs. MRR

Abrasive Jet Machine was fabricated with following specification:

1. Diameter of nozzle = 3 mm

2. Type of abrasive particle – aluminum oxide (AlO2)

3. Pressure range – 5 to 8 kgf/cm2

4. Carrier gas used – Dry air

From the experiment conducted it was observed that:

1. As Nozzle Tip Distance increases, the Top surface diameter and Bottom surface

diameter increases

2. As the Pressure increases Material Removal Rate (MRR) also increases.

Conclusion:

Scope of Future Work:

In this fabricated abrasive jet unit experiment can be conducted :

1. By using different nozzle tip diameter.

2. By using different type of abrasive particles.

3. By using different sizes of abrasive particles.

4. By using different work material.

5. Also the abrasive jet machine can be improved by retrofitting,

computer numerical control (CNC)

References

M. Roopa Rani and S. Seshan “Abrasive Jet Machining-Process Variables and Current Application”Metals Materials and Process,1995 Vol.7 No.4,pp 279-290.

P K Ray and Dr A K Paul, “Some Studies on Abrasive Jet Machining” Journal of the Institution of Engineers (India) vol 68 part PE 2 November 1987

Alok K.Verma, Cheng Y. Lin Associate Professor ,Engineering Technology Dept. Old Dominion University Norfolk, Virginia “Parametric Study of the Efficacy of Cutting Process in Abrasive Jet Machining (AJM)”

P. C. Pandey & H.S. Shan ,” Modern Machining “ Tata McGraw-Hill Publishing Company , Edition :1980

Production Technology HMT Tata McGraw-Hill Publishing Company , Edition :1980

Maleev & Hartman “Machine Design “edited by O. P. Grover “ CBS Publishing & Distributor

Amitabh Ghosh & Ashok Kumar Malik “Manufacturing Process “East –West Press Private Limited ,New Delhi, Edition 1995

THANKS