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DOI:10.23883/IJRTER.2018.4285.5EUS1 13
Fabrication of Optimal Abrasive water jet Machining
using Finite element approach
Lavish Patel1, Mukesh Dubey2 1Mechanical Engineering Department, Bhilai Institute Technology, Durg 2Mechanical Engineering Department, Bhilai Institute Technology, Durg
Abstract—In this article a computational investigation has been carried out to examine the performance characteristics of abrasive water jet machining (AWJM). A two-dimensional model of
nozzle for AWJM has been developed using ANSYS 14.5 where the simulation has been performed
in ANSYS Fluent. The influence of operating pressure on nozzle outlet velocity has been examined.
The simulation has been under taken by SIMPLE Algorithm at high pressure. Moreover, effect of
various parameter of nozzle such as convergence angle, nozzle length, jet diameter ratio on turbulent
intensity, pressure distribution, and skin frictions have been seen
Keywords—AWJM, CFD, Velocity
I. INTRODUCTION
(In the field non-convectional machining, Abrasive water jet machining is the technique of
removing material from the surface owed to the erosive exploitation of fine-grained abrasive
particles which is allowed to impact at high velocity. To achieve this high velocity, the abrasive
particles are permitted to pass within a nozzle along with compressed carrier gas, which is typically
air. [1]
This machining process has the advantage over conventional machining processes i.e. it over
the accurate control on the material removal rate. The advancement in better and newer designs, the
convenience of tine-grained hard materials, and the development of improved quality,high strength,
nevertheless costlier materials have called for precise and accurate machining processes. Significant
research has been done so far in this area are reviewed and ideas regarding unexplored areas are
discussed in this paper. The potential of the technology is outlined and assessed.
II. LITERATURE REVIEW
P. S. Jain and A. A. Shaikh [2] studied the various processes for cutting the polymer matrix
composites like cotton fiber polyester composites. In this study they compared the processes like
CO2 Laser, water jet cutting and diamond saw cutting with their process parameters. Based on
experimentation carried out they concluded that laser cutting is better over water jet and diamond
saw cutting because of fiber pull out in diamond saw and fiber curling and pulling out in multiple
directions which is observed in water jet cutting. Regarding water jet cutting they commented that
fibers may be affected by water moisture.
According to Dirk [3] Cutting edge preparation is utilized to increase the stability of cutting
tools and to improve the adhesion strength of a subsequent coating. In his work wet abrasive jet
machining with a robot guided system allows to prepare local tool areas and to realize a specific
design of the cutting edge, as well as advantageous surface qualities. His work concentrates on the
requirements and challenges in preparing and designing the cutting edge micro shape using wet abrasive jet machining. Important factors of the process as well as resultant shapes and topography
effects of the machined cutting edges are discussed.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 14
Pawar et al. [4] Silicon nozzle with high wear resistance in this process. The erosion rate is
depend upon variable pressure and standoff distance. In this experimental investigation sea sand is
using as abrasive material first time for erosion process in Abrasive Jet machining process. The
material removal rate at different condition were calculated by changing pressure and standoff
distance. The study of work surface found to be 0.0289 gm/sec and at the pressure 5 kg/cm2. The
analysis of 95% prediction bound of the silicon carbide has generated cubic polynomial model and R
square value is 0.9897 which is very closed 1. The value obtained of MRR experimentally and after
the calculation is within the limit and percentage of error is very less. The relative hardness of
abrasive against targeted material which is not taken into consideration of model. The depth of
cutting hole type are 4 mm to 6 mm. on glass work piece. In contrast to conventional erosion from
some studies elaborated by using abrasive water jet machine and no detailed investigation were
carried out about sea sand as an abrasive material.
Srikanth and Rao [5] Abrasive jet machining also known as micro-abrasive blasting or pencil
blasting is a non-traditional machining process in which the metal removal takes place due to high
velocity abrasive particles. The abrasive particles are propelled by high velocity carrier gas
(commonly air). This process is specially used for edge shapes and intricate shapes. The metal
cutting or drilling is performed due to high impact of abrasive particles on the work surface. This
machining technology proves good results when tool life is taken into consideration, given the fact
that the abrasive material can be reused several times before abrasive particles lose their cutting
effect. It is already proved that this technique is effectively adopted for polishing and deburring
processes. The present study highlights the influence of different parameters of Abrasive jet
machining like Pressure, SOD, Abrasive Flow Rate, on the Metal removal and Kerf width on
Ceramic Tiles, the type of abrasive particle used for this experiments is Al2O3. The experiments are
conducted according to TAGUCHI method of L9 orthogonal array and RSM, latter compared with
the Results of ANOVA using STATGRAPHICS.
Roxana Nedelcu [6] analyzed conventional and non-conventional machining processes of
composite cutting and stated the requirements of each process along with their advantages and
disadvantages. She considered conventional processes like turning, drilling, milling and grinding and
nonconventional processes like abrasive water jet machining, laser machining technique, electric
discharge machining and ultra-machining. She did not recommend particular processes for composite
cutting but concluded that every composite material possesses unique machining characteristics and
machining processes should be selected according to material characteristics.
Shah [7] conducted experimental investigations to study the effect of abrasive water jet
machining process parameters on material removal rate of granite material. Analysis of variance
(ANOVA) is carried out to optimize the AWJM process parameters for effective machining. He
considered the process parameters like abrasive water pressure, transvers speed and standoff distance
for his studies. Based on experimental investigations he formulated a mathematical model to predict
the material removal rate. Based on the results obtained he concluded that transvers speed is most
significant factor in deciding the MRR. MRR increases with increase in hydraulic pressure and SOD
up to a certain limit.
Alberdi et al. [8] aims at studying the behaviour of a machinability model in composite
materials. The machinability index for various composite materials with different thicknesses was
found experimentally, which showed very different results for different materials. A study of the
effect of the abrasive waterjet process parameters on the quality of cut (taper and surface roughness)
was carried out.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 15
However, AWJ cutting of composite laminates possesses several challenges. There are a few
studies that analyse the effect of input parameters on the quality of the cutting edge, e.g. Kalla et al.
[9], Shanmugan and Massod [10] and Wang [11], or investigations that optimise process parameters
for trimming CFRP materials with good quality, e.g. Etxeberria et al. [12]. Nevertheless, industrial
end users still need to develop process knowledge, since machine manufacturers do not provide good
databases for composite cutting. It is necessary to develop a methodology to adapt the process
parameters for each type of FRP & CFRP material which will allow AWJ trimming operations to be
easily carried out on composite materials.
III. MATHEMATICAL MODELLING
In system abrasive water jet machining is been analyzed with different aspect ratio. The wall shear
stress is analyzed during cutting process and the effect of nozzle convergence has been examined, in
additional to varying the orientation also the heat transfer and shear stress is taken in consideration
with the wall surface of the nozzle.
The equations governing this problem are those of Navier-Stokes along with the energy equation.
The Navier-Stokes equations are applied to incompressible flows and Newtonian fluids, including
the continuity equation and the equations of conservation of momentum on the x and y
According to equations
2 1 11 2
1 2
2 2
1 1
2 2
2 1 2
1( )
u u uu u
t x x
u ug T T
x x x
1
* *
2
* *
1 2
0u u
x x
x1 momentum equation
1
* * * * *
* *1 1 1 1 1
1 2* * * * *
1 2 1 2
*Pr
*
u u u u upu u
t x x x x x
x2 momentum equation
1
2
** * * *
* *2 2 2 2
1 2* * * * *
1 2 1 2
2
*Pr
*
Pr *
uu u u upu u
t x x x x x
Gr T
Energy equation * * * 2 * 2 *
* *
1 2* * *2 *2
1 2 1 2*
T T T T Tu u
t x x x x
Since in order to check the accuracy of developed computational model of AWJM which is
coupled with Navier stokes equation and additional boundary conditions are provided through which
heat transfer and mass flow, stress, etc other parameters are calculated and contour figures are
generated and illustrated in the in this paper.
IV. MATHEMATICAL MODELLING The governing equation of abrasive water jet machining is solved by using ANSYS Fluent solver.
In ANSYS 14.5 computational model has been developed in geometrical section with given
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 16
geometrical parameters from the base paper i.e. [13-14]. After that the geometrical model is extended
to mesh section in which complete geometry of AWJM is discretized into various numbers of nodes
and elements whim is in order of 105 . Furthermore, the geometrical mesh model is further named
such inlet, outlet, axis, wall section, etc. so that proper boundary conditions can applied in order to
evaluate performance characteristics of abrasive water jet machining.
Without convergent nozzle
Convergent nozzle
Fig. 1 Computational model detail of AWSJ nozzle
Fig. 2 Boundary condition
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 17
V. RESULT AND DISCUSSION
Figure 3 Validation of present work with the Numerical Simulation and Experimental
work of Guihua et al. [13, 14]
In order to validate the present work a computational model of abrasive water jet machine has been
developed and compared with the available literature of Numerical Simulation and Experimental
work of Guihua et al. [13, 14] and found that the obtained results are within acceptable limit and
showing same trend as shown in figure 3.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 18
Figure 4 contour plot of velocity magnitude
Fig 4 shows the counter plot of velocity distribution cross the three-different nozzle. It can seen
that the velocity distribution in all the nozzle is quite different.
Figure 5-6 shows the turbulence intensity along the length of the nozzle corresponding to various
inlet operating pressure. It has been observed that with increasing operating pressure, turbulence
intensity significantly increases. In figure 5-6 the turbulence intensity reaches its peak value at the
narrow region just before the start of focus tube length and in the focus tube the turbulence intensity
has approximately been constant throughout the focus tube length. It can be seen in figure 6-7
From the above, it can be revealed that on changing section significantly increase change in
turbulence intensity takes place in the critical region.
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 19
Figure 5 Variation of turbulent intensity at 400bar
Figure 6 contour plot of turbulent Intensity
Fig. 7 Velocity distribution along the nozzle length
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 20
Fig 7 shows the Velocity distribution along the nozzle length. It has been seen that increase in
operating pressure the cutting velocity increases and get constant along the focal region of the
nozzle. It has also been observed that major increase in velocity is seen at the convergence section.
Fig.8 Effect of Nozzle convergence angle on turbulent intensity
Fig. 8 shows the effect of Nozzle convergence angle on turbulent intensity. It has been seen that
turbulent intensity first increases significantly and then start decreasing as nozzle convergence angle
increases.
Fig. 9 Effect of Jet diameter ratio on turbulent intensity
Fig. 9 shows the effect of Jet diameter ratio on turbulent intensity. It has been seen that turbulent
intensity decreases linearly as jet diameter ratio increases
VI. CONCLUSION
From the above investigation various conclusion has been drawn which are as follows:
This machining technique is best for machining composite material due to having low tool wear, nearly low thermal damage.
The cutting velocity increases as operating pressure increases.
The nozzle plays a major role in amplifying cutting velocity.
At higher convergence angle, the friction is more at the junction between the convergent and
International Journal of Recent Trends in Engineering & Research (IJRTER) Volume 04, Issue 05; May - 2018 [ISSN: 2455-1457]
@IJRTER-2018, All Rights Reserved 21
focal region.
The increase in abrasive content in the volume fraction leads to more wearing of nozzle, which leads to burr formation.
It has been seen that turbulent intensity decreases linearly as jet diameter ratio increases
It has been seen that turbulent intensity first increases significantly and then start decreasing as
nozzle convergence angle increases
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