Friction Welding: Working Principle, Advantages, Disadvantages, and Industrial Applications

Friction welding is a solid state welding technique with high automation and good quality. Learn about the working principle, advantages, disadvantages, and industrial applications of friction welding. The article covers types of friction welding, including inertial friction welding, continuous induction method, linear friction welding, and friction surfacing.

Running head: FRICTION WELDING 1
FRICTION WELDING
Name of Student
Institution Affiliation

FRICTION WELDING 2
Abstract
Friction welding is a solid state welding technique with high automation and good quality.it
has been broadly applied in various industries especially in aerospace and automobile
industries. Because of high level of automation and less process parameters, the inertial
friction is common in many fields. There are many merits which are associated with the use
of friction welding in production such as, it is fast method of welding as compared to other
welding techniques. Even though there are many benefits which are associated with it, there
are also some drawbacks such as, is mainly used in round bars which have the same cross
section.
Table of Contents

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1.0 Introduction..........................................................................................................................3
2.0 Background..........................................................................................................................3
3.0 Principle...............................................................................................................................3
4.0 Advantages and disadvantages of friction welding..............................................................4
4.1 Advantages of friction welding...................................................................................4
4.2 Disadvantages of friction welding...............................................................................5
5.0 Industrial applications of friction welding...........................................................................5
5.1 Marine and shipbuilding industries.............................................................................6
5.2 Aerospace industry......................................................................................................6
5.3 Railway industry..........................................................................................................6
5.4 Other industries include...............................................................................................7
6.0 Types of friction welding.....................................................................................................7
6.1 Inertial friction welding...............................................................................................7
6.2 Continuous induction method......................................................................................8
6.3 Linear friction welding................................................................................................8
6.32 Process parameters...........................................................................................11
6.31 Numerical simulation of inertia friction welding process of gh4169 alloy.....11
6.4 Friction surfacing.......................................................................................................16
7.0 Conclusion..........................................................................................................................16
References................................................................................................................................18
1.0 Introduction

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Friction welding is defined as Solid state or a simply forge whereby the welding process
occurs between two mating surfaces of metals through the application of friction between
them. The welding technique has been adopted by well-known international companies in in
America and Europe such as American Manufacturing Foundry and Rockwell international to
manufacture their machines.
Friction welding is considered to be very essential in the production industry, by adopting
this welding method the high overhead costs which the companies will undergo to have this
technique in place will be balanced with the high production rates and lower labour
requirements.
The friction welding technique has many dimensional and hardware which are easily
adjustable making it to be very significant in the production of very small parts and
components. There are many industrial applications where friction welding can be applied
such as the machine and spare part production.
2.0 Background.
The process of friction welding was first discovered in the late 1920s, however during that
time there was very little data which was recorded about its use. A detailed discussion about
friction welding was recorded in the USSR in the early 1960s, but that time it was described
as ‘very doubtful, as a production technique due to the challenges in generating reciprocating
linear motion. The fist well-structured industrial research into friction welding took place in
the 1980s at TWI, UK, while the first ever research academic to be to be recorded took place
at Ohio State University, and the University Of Bristol, UK.
3.0 working Principle
The friction welding technique works on the basic principle of friction. In the process of
welding, friction is used to create heat at the interfaces surfaces (Anderson, 2016). The heat is

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used to join the two work pieces through the application of the external pressure at the work
pieces surfaces. In friction welding, the friction is applied until the plastic forming
temperature is reached which is usually900-1300oc for steel. After the heating process,
pressure which is uniformly increasing is applied to both of the metal work pieces until they
make a permanent joint.
4.0 Advantages and disadvantages of friction welding
4.1 Advantages of friction welding
There are many merits which are associated with the use of friction we in production. Some
of the merits include:
 It easier and convenient to join metals which are not similar and some of which are
considered to be unweldabl or incompatible.
 Friction welding is very fast method of welding as compared to other welding
techniques (Granjon, 2014).
 Due to their versatility the friction welders are able to join a wide range of materials,
shapes and sizes without any challenge.
 In this friction welding joint preparation is not of great importance since, saw cut,
machine and even the sheared surfaces are weldabl.
 The resulting joints are of forged quality, with up to 100% butt joint weld through the
contact area.
 Human error are eliminated by machine controlled process, and the quality of the
weld is independent of the operator skill.
 It is environmental friendly as there is no objectionable fumes, gases or smoke that
are generated which needs to be exhausted.

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 In friction welding there are no consumable that are required, no filler material, flux
or shielding gases.
 The power requirements for friction welding as low as 20% of that which is required
for conventional welding processes.
 Since there is no melting which occurs there is no solidification defects such as gas
porosity, slag or segregation inclusions.
4.2 Disadvantages of friction welding
Even though there are many benefits which are associated with friction welding it has also
some drawbacks such as:
 This technique of welding is mainly used in round bars which have the same cross
section. Due to that the bars which are not of the same cross section cannot be welded. In
some industries welding of metals which are not round in shape is very common the
application pf friction welding for such cases is limited (Sahin, 2016).
 There are exist holes left when the tools are withdrawn. Most of the metal bars which are
to be joined together are held by strong tools which drills holes through them.
 Friction welding requires extensive clamping
 Needs special backing support
 The cost of setting up a friction welding facility are very high. The equipment and
machines which are used for friction welding are very expensive to acquire. This makes a
lot of people to move to the convention welding which is much easier and cheaper.
 The design of the joints is very limited.
 It involves critical preparations of work pieces (Welding InstituteElsevier Science &
Technology, 2010).

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5.0 Industrial applications of friction welding
Many production industries all over the world are experiencing the high costs of energy due
to the amount of energy which is consumed during the production process’s adoption of
friction welding can greatly assist in solving this challenges (Yilbas, 2016). The friction
welding has been applied in various industrial applications as discussed below:
5.1 Marine and shipbuilding industries
The marine and shipbuilding are among the earliest industries to adopt friction welding for
commercial applications (Anderson, 2016). Friction welding is suitable for the following
applications:
 Panels for side, decks, floors and bulkhead.
 Superstructures and Hulls
 Aluminium extrusions
 Booms and Mast for example for sailing boat
5.2 Aerospace industry
Currently the aerospace industry is welding production parts and prototype by application of
friction welding. There exist opportunities to weld, ribs, spars and stringers for civilian and
military aircrafts (Vill', 2015). The friction welding process can be considered for the
following:
 Fuselage, empennages, wings
 In the case of space vehicle the friction welding can be considered for cryogenic fuel
tank
 Scientific and military rockets
 Aviation fuel tanks

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5.3 Railway industry
The commercial production of high speed trains which are made from aluminium extrusions
that can be joined through friction welding has been published and the applications include:
 Trams, underground undercarriages and the rolling stock of railways
 Good wagons and railway tankers
 Container bodies (American Welding Society. Committee on Friction Welding, 2012)
5.4 Other industries include
 Electric motor housing
 Kitchens and cooking equipment
 Gas cylinders and gas tanks
 Axle tube, gears, drive line, valves and other components are friction welded.
 Connecting rods, Gear levers, drill bits are friction welded
 It regularly used to replace casting or forging assembly
 Truck rollers, and hydraulic piston rods are friction welded
 In welding shafts and tubes
 In electrical industries it is used for welding aluminium and copper equipment
 In pumps friction welding is used to weld pump shafts (Singh, 2016).
6.0 Types of friction welding
There exists many variations in the process which work on the same principle, due to that
there are various types of friction welding as listed below:
1. Continuous induce friction welding
2. Linear friction welding
3. Spin welding/Inertial friction welding
4. Friction surfacing

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6.1 Inertial friction welding
Inertial Friction Welding refers to a variation of the friction welding in which the required
energy to make the weld is provided mainly by the stored rotational kinetic energy of the
welding machine (Blau, 2012). In the Inertial Friction welding, one of the two workpieces is
connected to a flywheel while the other is prevented from rotating. The flywheel is then
accelerated to a given rotational speed which is predetermined, storing the required energy.
The motor driver is disengages and then the work pieces are joined together by the friction
welding force. This makes the faying surfaces to rub to each other under pressure. The kinetic
energy which is stored in the rotating wheel is released as heat through friction at the
interface of the weld as the wheel speed decreases. A forge force might be applied before the
flywheel completely stops (Wang, 2013). After rotation has stopped the forge force is
maintained for a predetermined period.
6.2 Continuous induction method.
In this welding process, the rotor I connected together with band brake. When the plastic
temperatures are achieved, the band brake which was connected comes into action with the
main role being is to stop the rotor but at the same time the pressure which is applied
continue to increase until the two work pieces joints well and thus the weld is achieved
(Yilbas, 2016).
6.3 Linear friction welding
Linear Friction welding is a solid-sate joining process which works through oscillating one
workpiece relative to another while under a large compressive force as shown in fig 1 below.
The friction which exist between the oscillating surfaces generates heat that causes the
material of the interface to plasticise (Blaga, 2015). The material which is plasticised is then
expelled from the interface causing the workpiece to burn-off (shorten) in the compressive

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force direction. In the process of burn-off the interface contaminants such as foreign oxides
and particles that can affect the properties and possibly the service life of a weld are expelled.
Once the workpieces are free from contaminants the metal to metal contact occurs which
leads to formation of an integral bond (Vill', 2015). Linear friction welding unlike other
methods of friction welding it takes place in four phases as listed below:
I. Phase 1: Initial stage
II. Phase 2: transition stage
III. Phase 3: Transition stage
IV. Phase 4: Forging and Deceleration phase
Phase 1 ( Initial stage):in this stage contact exist between asperities on the two surfaces
which are to be joined, then heat is generated because of friction shown in the figure below
.
Fig 1 : contact exist between asperities on the two surfaces

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The asperities deforms after softening , thus increasing the true area of the work pieces which
is in contact.axial shortening in the direction of the applied force is observed even tough it is
neligible.
Phase 2 ( Transition stage):The interface materails palcticise because of friction thus
becoming visious as shown in the figure below (Kim, 2017).
Fig 2: Transition stage
This makes the true area of the contact between the work pieces to increase to 100% of the
cross sectional area. More materials are softened as the heat conducts away. Due to the
expulsion of the viscous materials form the interface the burning-off starts to occur
(Metallurgists, 2013).
Phase 3 (Transition stage): During this phase axial shortening occurs at a constant rate by
the rapid expulsion of the viscous interface material and a quasi-steady-state condition is
also achieved, forming the flash as shown in the figure below (Friction Welding Technical
Group, 2010).

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Figure 3: Transition stage
Phase 4 (Forging and Deceleration phase): In this phase the workpieces are aligned and the
relative motion is stpoed.in some cases an addition forge force may be applied to assist the
weld to consolidate well (Ellis, 2013).
6.32 Process parameters
During linear friction there are eight are six parameters which are used as listed below.
 Oscillation amplitude
 Oscillation frequency
 Ramp-up time
 Supplied force
 Normal force
 Axial shortening (American Welding Society. Committee on Friction Welding, 2012)

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6.31 Numerical simulation of inertia friction welding process of gh4169 alloy
The finite element model
The friction welding is a very complex process which involves the interactions friction force
and heat energy (Chaturvedi, 2016). The amount of heat which is generated at the friction
interface directly depend of the friction. An increase in the temperature distribution leads to
deformation of the body by thermal influences and strains the material thermal and
mechanical physical properties (Anderson, 2016) .Then the plastic deformation changes the
mechanical work into heat energy by a process which is not reversible.
The figure below shows the weldment.
Fig 4: the weldment
R1 is the inner radius of weldment near the frictional interface and R2 is the outer radius
The balance relation of flow of heat is presented in the analysed domain Ὼ by the following
axisymmetric heat transfers Equations.

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Where by:
T is current temperature
k(T) is thermal conductivity,
C (T) p is the heat specific
The expression of q is
Where by:
is the coupling is factor for the thermo-mechanical action and denotes the rate
of internal heat generation during the plastic deformation.
a is thermal efficiency of plastic deformation.
qi is the internal heat source.
The initial temperature of the parts is uniform and is described as:
On the free surface, the boundary condition is given as following:
and

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Where h1 is the convection coefficient and h2 is the radiation coefficient. Ts is the surrounding
temperature. On the friction surface, the boundary condition is written in the following
equation
Where q(r,t) is the heat flux at friction surface and described as:
Where
The friction coefficient during the initial stage of the inertia friction welding process is
described as following:
Where T , P ,V are the temperature, pressure and linear velocity in the frictional interface.
a ,b , c , fo are the constant obtained from experiments. During the steady- friction stage of
the inertia friction welding process, the friction coefficient is described as
Where by:

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The calculation model for stress and strain fields of the welding process is described by
Kirchhoff balance equation
Where
is Kirchhoff stress tensor
is Green strain tensor,
is component of virtual displacement,
Poi and Toi are unit volume force component acting on the deformed body respectively. The
strain increment consists of the elastic strain increment and the plastic train
increment
The stress increment is calculated as follows

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Where is the elastic-plastic matrix. The nonlinear governing equation group could
be obtained when the above two models were dispersed through finite element method.
6.4 Friction surfacing
This process id developed from friction welding process whereby a coating material is
applied to substrate. Simply it can be referred to as a surface coating process. A rod which is
made up of the coating material and referred to as mechatrode (Lovell, Chiocago) .It is then
rotated under given pressure in order to generate a plastic type of layer in the rod at the
interface between the rod and the substrate, through the movement of the substrate across the
face of the rod which is rotating a plastic layer is deposited (American Welding Society.
Committee on Friction Welding, 2012).
7.0 Conclusion
In conclusion, the friction welding technique works on the basic principle of friction. In the
process of welding, friction is used to create heat at the interfaces surfaces. The heat is used
to join the two work pieces through the application of the external pressure at the work pieces
surfaces.
The friction welding has many advantages such as, It is environmental friendly as there is no
objectionable fumes, gases or smoke that are generated which needs to be exhausted. In
friction welding there are no consumable that are required, no filler material, flux or shielding
gases. The power requirements for friction welding as low as 20% of that which is required
for conventional welding processes. (Blaga, 2015)

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The friction welding technique has many dimensional and hardware which are easily
adjustable making it to be very significant in the production of very small parts and
components. There are many industrial applications where friction welding can be applied
such as the machine and spare part production (Agarwal, 2015).
Friction welding has a wide range of applications such as in the railway systems, shipping
building and other marine operations, aerospace industry and the manufacture of spare and
other components.
Timeline
no Duration Proposed work resources
1
2
3
4
5
6
References
Agarwal, L. (2015). Spot friction welding of Mg-Mg, Al-Al and Mg-Al alloys. Chicago:
University of Michigan-Dearborn.

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American Welding Society. Committee on Friction Welding, A. W. (2012). Recommended
Practices for Friction Welding. Chicago: American Welding Society,.
Anderson, E. S. (2016). Design of a machine for thin-foil friction welding process
development. Paris: Madison.
Blaga, L.-A. (2015). Ths solid phase welding of metals. Paris: John Wiley & Sons,.
Blau, P. J. (2012). Friction Science and Technology: From Concepts to Applications, Second
Edition. London: CRC Press.
Chaturvedi, M. C. (2016). Welding and Joining of Aerospace Materials. London: Elsevier
Science.
Daniela Lohwasser. (2014). Friction Stir Welding: From Basics to Applications. Chicago:
Elsevier, .
Ellis, G. (2013). Friction Welding in Production. Berlin: Society of Manufacturing
Engineers.
Filho, S. T. (2011). Joining of Polymer-Metal Hybrid Structures: Principles and
Applications. London: John Wiley & Sons,.
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Butt Joints in Metals for High Duty Application. Texas: Welding Institute,.
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International Conference Held at Trondheim, Norway, 27-28 June 1983, under the
Auspices of the International Institute of Welding. Texas: Elsevier,.
Kazem Besharati Givi. (2017). Advances in Friction-Stir Welding and Processing. Chicago:
Elsevier Science & Technology,.

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Kim, J. K. (2017). A study on plastic flow of metal in inertia friction welding. Chicago:
Cornell University.
Lovell, C. M. (Chiocago). Friction Welding for High Performance Aerospace Applications.
TYexas: University of Birmingham.
Metallurgists, I. o. (2013). The Metallurgist and Materials Technologist. Paris: the University
of Michigan.
Sahin, A. Z. (2016). Friction Welding: Thermal and Metallurgical Characteristics. London:
Springer Science & Business Media,.
Singh, R. (2016). Applied Welding Engineering: Processes, Codes, and Standards. Auckland:
Elsevier.
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distributor.
Wang, K. K. (2013). Friction Welding. Chicago: Welding Research Council.
Welding InstituteElsevier Science & Technology. (2010). Recommendations for Friction
Welding Butt Joints in Metals for High Duty Applications. Texas: Elsevier Science &
Technology, .
Yilbas, B. S. (2016). Friction Welding: Thermal and Metallurgical Characteristics.
Auckland: Springer Science & Business Media.