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International Journal of Mechanical Engineering and Technology (IJMET) Volume 8, Issue 9, September 2017, pp. 132–139, Article ID: IJMET_08_09_013

Available online at http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=9

ISSN Print: 0976-6340 and ISSN Online: 0976-6359

© IAEME Publication Scopus Indexed

DESIGN AND DEVELOPMENT OF A FIXTURE

FOR FRICTION STIR WELDING

G. C. Jadhav

PhD Scholar, Department of Mechanical Engineering, Government College of Engineering

Sant Gadge Baba Amravati University, Amravati, Maharashtra State, India

Dr. R. S. Dalu

Professor and Head, Mechanical Engineering, Government College of Engineering

Sant Gadge Baba Amravati University, Amravati, Maharashtra state, India

ABSTRACT

Friction Stir Welding being a solid-state process is free from defects generally

occurs in fusion welding process. FSW of aluminium alloy has been done on universal

milling machine. The high cost and non-availability of friction stir welding machine

motivated this research to design and make a new fixture. Many forces appear during

the friction stir welding process. They are torque, transverse, axial and lateral forces.

Due to presence of these forces the main challenge is to withstand all these forces and

this is one aim to fabricate the fixture. For FSW process there is design, development

and tested the new economical fixture for universal milling machine.

Keyword head: Friction stir welding, fixture, clamps, drilling, milling.

Cite this Article: G. C. Jadhav and Dr. R. S. Dalu, Design and Development of a

Fixture for Friction Stir Welding, International Journal of Mechanical Engineering and

Technology 8(9), 2017, pp. 132–139.

http://www.iaeme.com/IJMET/issues.asp?JType=IJMET&VType=8&IType=9

1. INTRODUCTION

Friction Stir Welding (FSW) was invented at The Welding Institute (TWI) of UK in 1991 as a

solid-state joining technique, and it was initially applied to aluminium alloys [1]. Many

various engineering industries will give importance for aluminum and aluminum based alloys.

Friction stir welding was initially applied to aluminium alloys [3, 4, 5]. A non-consumable

rotating tool with a specially designed pin and shoulder is inserted into the abutting edges of

sheets or plates to be joined and traversed along the line of joint. The parts have to be suitably

clamped rigidly on a backing bar to prevent the abutting joint faces from being forced apart.

The length of the pin is slightly less than the required weld depth (7). The plunging is stopped

when the tool shoulder touches the surface of the job. The tool shoulder should be in intimate

contact with the work surface. The function of tool is heating of work-piece, and movement of

material to produce the joint. The heating is accomplished by friction between the tool and the

G. C. Jadhav and Dr. R. S. Dalu


work-piece and plastic deformation of work-piece (8). The localized heating softens the

material around the pin and combination of tool rotation and translation leads to movement of

material from the front of the pin to the back of the pin. Because of various geometrical

features of the tool, the material movement around the pin can be quite complex [9]. Here a

substantial forging force is applied by the tool to consolidate the plasticized metal behind the

tool. The welding of the material is facilitated by severe plastic deformation in the solid state

involving dynamic recrystalisation of the base material. As the tool is moved along the seam

the desired joint is created. The schematic view of the operation is shown in Figure1 [10].

Figure 1 Friction Stir Welding

Friction stir welding is considered to be the most significant development in metal joining

in decades and in addition, is a “green” technology due to its energy efficiency, environmental

friendliness, and versatility [3, 4, 12]. The benefits include the ability to join materials which

are difficult to fusion weld, such as aluminum alloys. The process is suitable for automation

and adaptable for robot use. The welding process does not need filler wires and weld pool

shielding gas. No porosity, splatter, grinding, brushing or pickling required in mass

production Oxide removal immediately before welding is unnecessary. The process is clean

and does not produce any major safety hazards, such as welding fume or radiation [6].

1.1 Difficulties in FSW

A good design of fixture can lead to dissipating heat away from the workpiece, and hence

improving the weld quality and performance [13]. He developed a fixture that accommodates

both backing plate and metal plate to be welded [14]. There is development of a clamping

system and an instrumented setup for a vertical milling machine for friction stir welding

(FSW) operations and measuring the process forces. Taking into account the gap formation

(i.e., lateral movement) and transverse movement of the workpiece, a new type of adjustable

fixture was designed to hold the workpiece being welded [15]. The fixture required to carry

out the FSW process efficiently in a conventional milling machine is not well discussed in

published literatures. Friction stir welding has been used for purpose-designed equipment or

modified existing machine tool technology. The future is bright because it will open many

more cost- effective opportunities for FSW in many industries such as railway, marine,

transportation, refrigeration and electrical [7].

Design and Development of a Fixture for Friction Stir Welding


Difficulties faced in FSW process from the above research paper are: -

1. Fixture arrangement will be required.

2. It creates a visible hole in welding plates.

3. High initial or set up cost.

4. It is less flexible compared to arc welding process.

5. It cannot make filler joint.

2. PROPOSED RESEARCH PLAN

The aim of this paper was to develop a set up for FSW and fabricate defect free weld. Any

machines to achieve specific tasks have been considered very important in the industry. The

high cost of specialized machines makes them less accessibility and usability. Here the

modifications in machines are necessary meet specific tasks with low cost and simple way.

Due to high cost and non-availability of FSW machine motivated to design and make a new

fixture. Also many forces appear during the friction stir welding process. They are torque,

transverse, axial and lateral forces. Due to presence of these forces during the friction stir

welding process, the main challenge was to withstand all these forces and this was one of the

aims to developing the fixture.

2.1 About machine and work piece

Universal milling machine has been used for experimentation. Vertical attachment has used to

hold the FSW tool. Two work piece of rectangular shape have been used to joint by FSW

process. One end made a drill of 6 mm on the surface of the workpiece so that shoulder of the

tool rest on the workpiece easily. It is easy to support the axial force on workpiece. Figure 2

and 3 shows the milling machine and the workpiece use for FSW purpose.

About Machine: Specification:

Figure 2 Milling Machine

Name of company: Batliboi Ltd, Surat.

Name of machine: Universal milling machine BFU-5

Spindle

Table Size

Transverses: Longitudinal

Cross

Spindle Speed

Spindle Feed

Spindle Power

ISO40

1430 x 320

810 mm

405 mm

45 – 2000 rpm

14 – 750 mm/min

5.5 kw

About Workpiece:

AA 6061-T6 aluminum alloy of thickness 6.3mm, chemical

composition and mechanical properties are given in table 1 and 2

respectively.

Table 1 Chemical composition in %wt.

Mg Si Fe Cu Cr Mn Zn Ti Al

0.9 0.62 0.33 0.28 0.17 0.06 0.02 0.02 Balance



Figure 3 Workpiece

Table 2 Mechanical properties.

Yield

strength

inMPa

Ultimate

strength in

MPa

Elangation

%

Hardness in

HV

110 207 16 75

3. DESIGN AND DEVELOPMENT OF FIXTURE

The main purpose of a fixture for friction stir welding is to hold the work pieces in position

during welding. However, there has limited published information that details the fixture

design requirements. In each of joint designs and fixture arrangements, it is necessary to give

enough area for welding tool shoulder path, provide enough force to prevent motion of the

workpiece, provide adequate heat sink to dissipate the heat of welding.

A workpiece, just like any free solid body, has twelve degrees of freedom such as six

rectilinear displacements and six angular displacements along the mutually orthogonal co-

ordinate axes. The general principle of 3-2-1 location is most commonly used. During a set-

up, it is necessary to restrict certain degrees of freedom so as to locate and orient the active

surfaces with respect to the FSW tool. Since supporting or restricting surfaces may vary from

the true geometrical shape, especially on rough-machined surfaces or cast blanks, it is

desirable that the workpiece be located with respect to the point supports. Here the first three

points the large area of base plate is taken and for two points the fixed side plate does this

work. Here instead of three pins plane flat base is used. By using this five directions of

movement are restricted. To restrict the three movement of the part around Z axis and the

direction Y axis, here instead of two pin fixed flat supporting plate is used. The remaining

four degree of freedom has been restricted by a C- clamp.

A fixture consists of a set of locator and clamps. Locators are used to determine the place

and orientation of a workpiece, whereas clamps exert clamping forces so that the work piece

is press firmly against locator. Clamping has been appropriately planned at the stage of

machining fixture design. The design is simple, cost effective and will be fastened on any

milling machine bed. The fixture is made up of various parts. To fabricate the system from

one piece is too difficult taking in account the high cost and complexity. During the initial

stages, many pieces were fabricated separately then one of them was joined together to form

as a single component. CATIA P3 V5 R17 software package is used to prepare the part

drawings and elements to the engineering drawing to design the fixture. This reduces the time.

The various parts are described briefly in Figure 4.

A. Work piece: AA6061-T6 of thickness 6.34 mm.

Size: 100 x 82x 6 mm

Operation: Cutting, filing, drilling and finishing.

Machine used: Hydraulic power hacksaw and drilling.



B. Base plate: Because of the increased tool forces, fixtures

are built stronger and heavier. The material used for this is

mild steel having dimensions 216x168x20 mm and weight of

base plate 5.63 kg. Base plate has 13 drills with threading of

10 mm.

C. Fixed plate: Left side of base plate having dimension

216 x 25 x 10 mm is directly joined by arc welding to the

base plate as shown in assembly of fixture.

D. Side supporting plate: This plate is movable and having

dimensions 204 x 62 x 10 mm. This plate has 100 mm

groove having depth 5 mm and breath is 6 mm. Also have

three 10 mm drill holes. T-bolts are used to locate the

workpiece position. Also position of the locator should space

as far apart from the actual welding position. Fool proofing

is that it ensures that workpiece fit into the tool only in its

correct position.

E. C-Clamps: Two clamp plates made of mild steel flat with

dimensions 164 x 32 x20 mm are used to prevent the axial

movement and vibration of the work pieces. Each plate is

provided with three holes of 10 mm. Here clamp is designed

by the shape and size of the workpiece, the fixture being

used, and the work is to be done. Two hole of 6 mm and

depth 20 mm used for connecting hinges. So easily

unloading of workpiece done.

F. Backing plate: This plate is made up of stainless steel

having dimensions 160 x 100 x 3 mm. The use of this plate

prevents the damage of fixture during welding also reduce

the heat transfer from welding to base plate.

Figure 4 In CATIA 3D view of the various components of the system

3.1 Developing the fixture

Considering above versatile features, the design of fixture was prepared using the CATIA.

Assembly as shown in Figure 5 has been prepared by measuring the dimensions of the bed of

universal milling machine on which the FSW has to be performed. Mild steel has been used

for manufacturing the parts due to its high strength and toughness which is required to

withstand unbalanced force and pressure during FSW operation.



Movable supporting plate C-clamps Hinges Base plate Fixed Side plate

Figure 5 Draft of fixture design

4. FABRICATION AND TESTING OF THE FIXTURE

After finalizing the drawing details and product design features, all main parts were fabricated

at small dimensional tolerance. They were fabricated individually before assembled together

by using bolts and fasteners. The final product is shown in the Fig.5. Different parts of

fixtures are fabricated in our workshop. The parts list of fixture as shown below Table 1.

Table 1 Parts used in fixture

Part List

A. Workpiece Aluminium 2

B. Base plate M.S. 1

C. Movable supporting plate M.S. 1

D Fixed side plate M.S. 1

E. C-Clamp M.S. 2

F. Backing plate S.S. 1

G. Nut and bolt C-30 9

H. Hinges S.S. 2

The fabricated fixture of universal milling machine was tested for its stability and

reliability, by operating it at various parameters during the FSW process. Figure 6 shows the

experiment setup where the fixture was fastened on the milling machine table. Non-

consumable tool made of high chromium high carbon steel with varying speed, feed, axial

pressure, tilt angle, shoulder diameter; 4.2 mm pin length and 6 mm pin diameter was selected

for this operation.

The fixture was successfully mounted on the milling machine table. Few samples were

successfully joined by friction stir welding process. During the operation no vibration was

observed and also there was no distortion in the samples.



Final fixture with sample

Testing of fixture

Testing Samples of AA6061T-6

Figure 6 Final product of FSW fixture with testing samples

4. CONCLUSION

Proposed fixture has been designed, developed and tested successfully on universal milling

machine (BFU-5).It possesses the strength to sustain downward load acted by the spindle

force against its structure The advantage of utilizing the existing milling machine by adopting

the application of fixture for FSW process can be justified economically, where it is more

affordable compared to purchasing an actual FSW machine.

REFERENCES

[1] Thomas WM, Nicholas ED, Needham JC, Murch MG, Temple-Smith P, Dawes CJ,

Friction stir butt welding, International Patent Application No. PCT/GB92/02203; 1991

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1996, 75, pp. 41–45

[3] Thomas W. M. and Nicholas E. D., Friction stir welding for the transportation industries,

Materials & Design, 18,1997, pp.269-273.

[4] Thomas W. M., Friction stir welding – recent developments, Mater Sci. Forum 2003;

426–432:229–36.



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International (2003), 17(3), pp.341-345.

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