Design and Experimental study of Friction stir welding of AA6061-T6 Alloy for optimization of welding parameters by using Lathe Machine

International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395 -0056
Volume: 04 Issue: 3 | March-2017 www.irjet.net p-ISSN: 2395-0072
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Design and Experimental study of Friction stir welding of AA6061-T6
Alloy for optimization of welding parameters by using Lathe Machine
Piyush Patel1, Sachin Patel2, Hiren Shah3
1,2,3Assistant Professor, Mechanical Engineering Department, C G Patel Institute of Technology, Uka Tarsadia
University, Bardoli, Surat, India
---------------------------------------------------------------------***---------------------------------------------------------------------
Abstract - Friction stir welding is a new solid state
welding process for joining metallic alloys and it is useful
in serve industriesforjoiningaluminium,magnesiumand
copper alloys. The various parameter such as rotational
speed, transverse speed and tool tiltangleplay important
roles in FSW process and quality weld. The aim of this
study is to know the relation between the effects of
different transvers speed and tool profile on the weld
quality of AA6061-T6 aluminium. The geometry ofthepin
tool along with the process parameters plays an
important role in dictating the path that the material
takes. The tool geometry was carefully chosen and
fabricated to have a nearly flat welded interface pin
profile. In this work, an attempthasbeen madetoanalyze
the effect of various tool profiles on mechanical
properties of aluminium alloy. Various tool profiles have
been used to fabricate joints by using varying thickness
work piece of Aluminium alloy. Numerical techniques
particularly, the finite element method for thesimulation
of FSW for thermal, mechanical and thermo-mechanical
modelling has been investigated. The currentstudies also
aim to understandmechanicalpropertiesduringthe FSW.
Key Words: Friction Stir Welding, Transient Thermal
Analysis, Al6061, Process parameter, Tool Profile
1.INTRODUCTION
Friction Stir Welding process is relatively a new joining
process that is presently attracting considerable interest.
Since the joint can be obtained below the melting
temperature, this method is suitable for joining a number of
materials those are extremely difficult to be welded by
conventional fusion techniques. The process is solid state in
nature and relies on the localized forging of the weld zone to
produce the joint.
A constantly rotated non consumable cylindrical tool with a
profiled probe is transversely fed at a constant rate into
a butt joint between two clamped pieces of butted material.
The probe is slightly shorter than the weld depth required,
with the tool shoulder riding a top the work surface.
Frictional heat is generated between the wear
resistant welding components and the work pieces. This
heat, along with that generated by the mechanical mixing
process and the adiabatic heat within thematerial,causethe
stirred materials to soften without melting.
FSW is actually performed in different steps as shown in
figure 1. The probe primary function is to mix the material
under the tool shoulder, which can be enhanced by threads.
First, the probe is plunged into the joint formed by the two
sheets to be welded, until the shoulder gets incontact.Asthe
tool rotates at a high velocity, the sheets are heated up by
plastic deformation and friction. As the pin is moved
forward, a special profile on its leading face forces
plasticized material to the rear where clamping forceassists
in a forged consolidation of the weld. This processofthetool
traversing along the weld line ina plasticizedtubularshaftof
metal results in severe solid state deformation involving
dynamic recrystallization of the base material. Figure 1
shows process of tool traversing along the weld line. [1], [2]
(a)
(b)

(c)
Fig -1: Schematic representation of FSW process
1.1 Key of Benefits
In contrast to thetraditionalfrictionwelding,whichisusually
performed on small axisymmetric parts that can be rotated
and pushed against each other to form a joint, FSW can be
applied to various types of joints like butt joints, lap joints, T
butt joints and fillet joints.
Table -1: The key benefits of FSW Process
Metallurgical
benefits
Environmental
Benefits
Energy benefits
Solid phase process No shielding gas
required
Reduction in weight
Good dimensional
stability and
repeatability
Eliminate grindingwaste Decrease fuel
consumption
No loss of Alloying
elements
Eliminate solvents
required for degreasing
Excellent
metallurgical
properties in the joint
area
Consumable materials
saving such as rugs ,
wire or any other gases
1.2 Comparison of friction stir welding to other
welding processes
Comparison of FSW to other welding processes is typically
done within the context of justifying the use of the process
over other, more conventional techniques. Successful
application of FSW depends upon a clear misunderstanding
of the characteristics of the process, so favorable technical
and economic justification can be developed.
The unique, favorable characteristics of FSW compared to
traditional arc welding methods provide several sources for
technical justification for use of the process. [3], [4]
The main points for technical justification of FSW compared
to arc welding processes are;
 Improved weld ability
 Reduced distortion
 Reduced residual stress
 Improved cosmetic performance
 Elimination of under matched filler metal
 Improved static strength and ductility
 Mechanized process
 High robustness and few process variables
2. DESIGN APPROACH
Generally, Friction stir welding is performed on the Milling
or Radial cum drilling machine. But our main objective is to
perform operation onto Lathe Machine. So for that an
attachment is required to hold a welding plate on a lathe
machine. [9], [10]
2.1 Basic Requirement of machine:
The performance test on Lathe machine for the FSW
Technique is analyzed for the different parameters.
2.1.1 Light duty lathe machine specification:
Fig- 2: Lathe Machine
Table-2: Light duty lathe machine specification
Sr no Features Values
1 Swing over bed 90 mm
2 Swing over carriage 45 mm
3 Distance between center 430 mm
4 Overall length 820 mm
5 Overall width 220 mm
6 Overall height 200 mm
7 Shipping weight 140 kg
8 Hole through spindle 10 mm
9 Spindle speed range 575-900 rpm

2.1.2 Lathe attachment
Now for holding a welding plate on lathe machine an
additional attachment is required for mounting purpose.
Figure 3 show CAD Geometrical view of lathe attachmentfor
holding of welding plate.
Fig-3: CAD Geometrical view of Lathe Attachment
(All dimensions are in mm)
2.2 Basic requirement of tool geometry
A novel pin is design for friction stir welding tools that can
penetrate more apply into work pieces to form a thicker
weld joint without overloading the tool. The pin is providing
with cylindrical and taper face on surface of tool. The
diameter of the tool shoulder to the diameter of the tool pin
(Ds/Dp) are chosen based on the literature survey. The
shoulder of tool is designed to produce heatonthesurfaceof
the work pieces. The tool shoulder accounts for majority of
the deformation and frictional heat generation between the
work pieces. Due to large surface area, friction increases,
which in turn increases the amount of heat generated. [6],
[7], [8]
Fig-4. Tool Geometry
TABLE 3. Tool design parameter [15]
Weld tool Geometry AL TI Steel (HMTM)
DS/DP 2.4 1.2-3.8 2.3-2.4
DP/LP 1.5 1.4-1.9 1.7-2.0
Pin surface Treads Smooth Smooth
Taper 0 30-60 30-60
2.2.1 Types of tool
 Taper tool:
Fig- 5: CAD geometry of Taper Tool
 Cylindrical tool:
Fig- 6: CAD geometry of Cylindrical tool
2.2.2 Base plate
The welding regime in the FSW procedure is defined by
speed of rotation and the translational speed of tool, all of
which depend on the thermo-physical properties of the
material and the thickness of plates. [12]

Fig- 7: CAD Geometrical Dimension (All dimensions
are in mm)
3. SIMULATION BASED APPROACH
Three-dimensional thermo mechanical model and the
thermo mechanical effect of the welded material is
developed for the FSW of an Al-alloy, in order to build
qualitative framework tounderstandthethermomechanical
process in FSW. In this analysis work belowfigureshowsthe
total deformation and temperature graph for a cylindrical
tool geometry. The prediction and the measurement show
that the maximumtemperaturegradientsinlongitudinal and
lateral directions are located just beyond the shoulder edge.
To simulate this kind of welding process, a fully coupled
thermo-mechanical solution has been adopted to simulate
the FSW process. [11], [13]
Fig- 8: Total deformation and Temperature
profile
Figure 8 show the Total deformation and temperature
profiles in the work piece during the welding operation for
N2=900 rpm; T2 = 3.16 mm/min and for a cylindrical tool
profile for the size of 4 mm thickness plate. [14], [16]
4. EXPERIMENTAL WORK
Experimental setup was recognized using a light duty lathe
machine. No extra setup is required for friction stir welding
except tool and fixture, so as to place piece in proper
position during welding. The different process parameters
are discussed below which are effecting for the Analysis on
FSW. [15]
4.1 Process parameter
The various process parametersplayimportant rolesinFSW
process and quality weld.
Table 4: Main FSW process variables
Tool design variables Machine variables Other variables
Shoulder and pin
material
Welding speed Anvil material
Shoulder diameter Spindle speed Anvil size
Pin diameter
Plunge force or
depth
Work piece size
Pin length
Tool tilt angle
Work piece
properties
Thread pitch
Feature geometry
There are so many parameters are effecting for the analysis
on friction stir welding as shown in Table 4. As many
parameters are important in the friction stir welding but in
this experiment main two parameters are selected for
analysis by using lathe machine;
(1) Tool speed
(2) Transvers speed
The proper choice of tool rotation and transverse speed will
produce a good quality weld. The material use for base plate
is Al alloy 6061 and the material use for the tool geometry is
EN8.
4.2 Process step for friction stir welding on lathe
machine
The experimental study includes the butt joining of
aluminum plates. The welding method is carried outonlight
duty lathe machine as shown in Figure 2. Tool is hold in tool
arbor as shown in Figure 9. Welding jigs and fixtures are
designed to carry two plates as shown in figure 9. [5]

Fig-9: Process steps for FSW Experiment
In the present work, different FSW buttweldswereobtained
by varying the process parameters within the range and the
optimal values are drawn based on thetrendofthevalues.In
this experiment it is observed that the process parameters
like tool design, tool rotational speed, welding speed and
materials are the main parameters to produce the effective
butt joint by friction stir welding. [17]
4.3 Observation table
Table 5: Experiment data
Sr
No
Material
Aa-6061
RPM
(n)
Transvers
Speed
(mm/min
)
Pa
ss Material size
(mm)
T
o
o
l
1 Plate no:2 N2=900
T2=3.16
mm/min
P1 S2=100*45*4 C
2 Plate no:9 N9=900
T9=3.37
mm/min
P2 S9=100*45*6 C
3 Plate no:8 N8=575
T8=7.35
mm/min
P1 S8=100*45*4 C
4 Plate no:3 N3=575
T3=8.16
mm/min
P2 S3=92*45*6 C
5 Plate no:6 N6=900
T6=4.41
mm/min
P1 S6=100*45*4 t
6 Plate no:4 N4=900
T4=6.15
mm/min
P2 S4=100*45*6 t
7 Plate no:7 N7=575
T7=4.50
mm/min
P1 S7=100*45*4 t
8 Plate no:5 N5=575
T5=4.49
mm/min
P2 S5=100*45*6 t
Where;
Plate no 2: (P1N2T2S2C); Cylindrical Tool =C;TapperTool =
t; RPM = N; Transvers speed = T; Material size = S; Single
pass = P1; Double pass = P2
4.4 Tensile Tests: -
Tensile strength, along with elastic modulus and corrosion
resistance, is an important parameter of engineering
materials used in structures and mechanical devices.
 Tensile test specimen geometry
Fig-10: Tensile test specimen (All dimensions are
in mm)
 Sub size specimen:
G: Gauge length: 25 + 0.08mm
W: Width: 6.25 + 0.05mm
T: Thickness: Thick of material plate
R: Radius of fillet: 6 mm
L: overall length: 100mm
A: Length of reduced section: 32mm
B; Length of grip section: 32mm
C: Width of grip section: 10mm
4.5 Tested plate and results
Fig- 11: Tested plate (All dimensions are in mm)

The process parameters selectedweremainlytool rotational
speed, welding speed and tool geometry etc. Tests are
performed as per the ASTM Standards at TCR Advance
Engineering at Vadodara. A machined specimen is placed in
the testing machine and load is applied to measure the
resistance of a Material. The result for tensile strength for
sample specimen is shown in Table 6.
Table 6: Tensile strength of sample specimen
Sr no
Plate no
Force
(KN)
Area
(mm2)
Ultimate tensile
strength (N/mm2)
1 P2 15440 158.35 98
2 P9 7640 163.11 47
3 P10 5679 87.95 65
4 P11 4420 98.57 45
Figure 12 shows the load vs displacement graph for varying
thickness of plate on Tensile strength.
Fig-12: Tensile test graph (6 mm & 4 mm)
5. CONCULUSION
Important process parameters that control thequalityofthe
weld are rotation speed (575 - 900 rpm) and traverse speed
(3.16 - 8.16 mm/min) were performed to obtain defect free
welded joints.
The following various conclusions summarize the present
paper;
 From this investigation, it has been found that tool
profile cylindrical tool, transvers speed 3.37 mm/min
and rotational speed is 900 rpm produced good tensile
strength.
 Mechanical properties of the joints increase with
increase in tool rotational speedandreachesmaximum
at 500 to 575 rpm but again deceases with further
increase in tool rotational speed.
 The heat input from the tool shoulder was assumed to
be the frictional heat. The coefficient of friction was
continuously adjusted to keep the calculated
temperature fromexceedingthematerial meltingpoint.
 Increase in pin length decreases penetration depth on
the back side of welded plate. It is also observed that
more than 6 mm thickness of work piece is possible to
weld by friction stir welding butt. The condition is to
design a different tool for different thickness. While
designing tool, the tool tip length should be less than
the thickness of the base material i.e less than 0.25 to
0.8 times of the base the material thickness.
REFERENCES
[1] Chunlin Dong (2009), “Microstructure and mechanical
properties of friction stir welded joints in 2219-T6
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3467.
[2] Aritoshi, M., and Okita, K. 2002, “Friction welding of
dissimilar metals” Journal of Japan Welding Society 71-
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Murayma, G.; Saita, K.; Oikawa, H, “Dissimilar metal
joining technologies for steel sheet and aluminum alloy
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[4] Nandan, R.; DebRoy, T.; Bhadeshia, H.K.D.H, “Recent
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[13] Chen C.M., Kovacevic R. 2003, “Finite Element Modeling of
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BIOGRAPHIES
Mr Piyush T Patel, (M.Tech. with
specialization in CAD-CAM), having
a 3.5 years of experience in
academics. Presently he is working
as Assistant Professor in CGPIT,
UTU, Bardoli.
Mr Sachin D Patel, (M.Tech. with
specialization in Industrial Process
Equipment Design),havinga 4years
of experience in academics.
Presently he is working as Assistant
Professor in CGPIT, UTU, Bardoli.
Mr Hiren A Shah, (M.E. with
specialization in Thermal), having a
4.5 years of experience in
academics. Presently he is working
as Assistant Professor in CGPIT,
UTU, Bardoli.

Design and Experimental study of Friction stir welding of AA6061-T6 Alloy for optimization of welding parameters by using Lathe Machine

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Design and Experimental study of Friction stir welding of AA6061-T6 Alloy for optimization of welding parameters by using Lathe Machine