{{Short description|Solid-state welding process}} {{Update|date=March 2023}} '''Friction welding (FWR)''' is a solid-state welding and bonding process that generates heat through mechanical friction between workpieces in relative motion to one another. The process is used with the addition of a lateral force called "upset" to plastically displace and fuse the materials.<ref>{{cite book |doi=10.1016/B978-0-12-819726-4.00012-0 |chapter=Solid State Welding for Fabricating Metallic Parts and Structures |title=Encyclopedia of Materials: Metals and Alloys |date=2022 |last1=Li |first1=Wenya |last2=Patel |first2=Vivek |pages=246–259 |isbn=978-0-12-819733-2 }}</ref> Friction welding is a solid-state welding technique similar to forge welding. Instead of a fusion welding process, friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.
The ISO norm of friction welding is EN ISO 15620:2019,<ref name=":4">{{Cite web|title=EN ISO 15620:2019|url=https://www.iso.org/obp/ui/#iso:std:iso:15620:ed-2:v1:en|access-date=2020-12-28|website=www.iso.org}}</ref> which contains information about the basic terms, definitions, and tables of the weldability of metals and alloys.
==History== thumb|Historical photo of a double spindle machine for rotary friction welding Some applications and patents connected with friction welding dates back to the turn of the 20th century,<ref name=":1">{{cite journal |last1=Wang |first1=K. K. |last2=Lin |first2=Wen |title=Flywheel friction welding research |journal=Welding Journal |volume=53 |issue=6 |date=1974 |pages=233s–241s }}</ref> with rotary friction welding (RFW) being the oldest of the methods.<ref name=":18">{{cite book |last1=Mucic |first1=Kemal |last2=Lopera |first2=Jose |last3=Fuchs |first3=Franz |last4=Enzinger |first4=Norbert |chapter=Linear friction welding of high strength chains: modelling and validation |pages=203–218 |editor1-last=Sommitsch |editor1-first=Christof |title=Mathematical Modelling of Weld Phenomena 10 |date=2013 |publisher=Verlag der Technischen Universität Graz |isbn=978-3-85125-293-4 }}</ref> W. Richter patented the method of linear friction welding (LFW) process in 1924<ref name=":19" /> in England and 1929<ref name=":19" /> in the Weimar Republic. The description of the process was vague<ref name=":18" /> and H. Klopstock patented the process in the Soviet Union in 1924.<ref name=":19">{{cite book |last1=Uzkut |first1=Mehmet |first2=Bekir Sadık |last2=Ünlü |first3=Selim Sarper |last3=Yilmaz |first4=Mustafa |last4=Akdağ |date=2010 |chapter=Friction welding and its applications in today's world |pages=710–724 |chapter-url=https://omeka.ibu.edu.ba/items/show/3150 |title=Proceedings of the 2nd International Symposium on Sustainable Development }}</ref> The first description and experiments related to rotary friction welding took place in the Soviet Union in 1956,<ref name=":1" /><ref name=":19" /> when a machinist named A. I. Chudikov researched scientific studies and suggested the use of the welding method as a commercial process.<ref name=":19" /> The process was introduced to the United States in 1960.<ref name=":1" /> The American companies Caterpillar Tractor Company (Caterpillar - CAT), Rockwell International, and American Manufacturing Foundry all developed machines for the process. Patents were also issued throughout Europe and the Soviet Union. The first studies of friction welding in England were carried out by the Welding Institute in 1961.<ref name=":19" />
In the United States, Caterpillar Inc. and Manufacturing Technology Inc. (MTI) developed an inertia process in 1962.<ref name=":1" /><ref name=":19" /> In Europe, KUKA AG and Thompson launched rotary friction welding for industrial applications in 1966,<ref name=":21" /> developed a direct-drive process, and in 1974,<ref name=":21" /> built the rRS6 double spindle machine for heavy truck axles.<ref name=":21">{{Cite web|title=Rotary friction welding machines|url=https://www.kuka.com/en-us/products/production-machines/rotary-friction-welding-machines|access-date=2020-12-27|website=KUKA AG}}</ref> Another method was invented in the Soviet Union by Yu. Klimenko in the mid-1960s and patented in 1967,<ref>{{cite web | title=SU195846A1 - Method of welding metal by Friction | website=Google Patents | date=20 April 2006 | url=https://patents.google.com/patent/SU195846A1/en | access-date=22 May 2023}}</ref> experimentally proven and developed into a commercial technology at The Welding Institute (TWI) in the United Kingdom and patented again in 1991: the friction stir welding (FSW) process,<ref name=":162">Thomas, W.M., Nicholas, E.D., Needham, J.C., Murch, M.G., Templesmith, P., Dawes, C. J., 1991. Improvements to Friction Welding. GB Patent Application No. 91259788.</ref> is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material.
An improved modification of the standard friction welding technique is [https://blog.mtiwelding.com/low-force-friction-welding low force friction welding], a hybrid technology developed by EWI and MTI, which "uses an external energy source to raise the interface temperature of the two parts being joined, thereby reducing the process forces required to make a solid-state weld compared to traditional friction welding".<ref name=":3">{{Cite web|last=Jones|first=Simon|title=Low Force Friction Welding -- What is it?|url=https://blog.mtiwelding.com/low-force-friction-welding|access-date=2020-12-28|website=blog.mtiwelding.com|date=2 December 2020 }}</ref> The process applies to both linear and rotary friction welding.<ref>{{cite journal |last1=Zurawski |first1=Pawel |title=Analysis of low force friction welding process in the industrial environment |journal=International Journal of Engineering and Innovative Technology |date=15 February 2022 |pages=1–9 |doi=10.51456/IJEIT.2022.v11i07.001 |doi-access=free }}</ref>
==Metal techniques== Friction welding takes many forms but the following are the most popular methods used.<ref>{{cite web |title=Friction Welding 101: Whiteboard Wednesday |url=https://www.mtiwelding.com/blog/friction-welding-101-whiteboard-wednesday/ |website=MTI Welding |date=11 January 2019 }}{{self-published inline|date=December 2024}}</ref>
===Rotary friction welding=== {{Main|Rotary friction welding}} thumb|Rotary friction welding Rotary friction welding (RFW) is one of the main methods of friction welding. One welded element is rotated relative to the other and pressed down. The heating of the material is caused by friction work and creates a non-separable weld.<ref>{{cite web |title=Rotary Friction Welding - Job Knowledge |url=https://www.twi-global.com/technical-knowledge/job-knowledge/rotary-friction-welding-148 |website=TWI }}</ref>
===Radial friction welding=== Radial friction welding is a type of friction welding similar to rotary friction welding and is generally used to weld pipes together.<ref>{{cite journal |last1=Chludzinski |first1=Mariane |last2=dos Santos |first2=Rafael Eugenio |last3=Pissanti |first3=Daniela Ramminger |last4=Kroeff |first4=Filipe Cantelli |last5=Mattei |first5=Fabiano |last6=Dalpiaz |first6=Giovani |last7=Piza Paes |first7=Marcelo Torres |title=Full-scale friction welding system for pipeline steels |journal=Journal of Materials Research and Technology |date=1 April 2019 |volume=8 |issue=2 |pages=1773–1780 |doi=10.1016/j.jmrt.2018.12.007 |url=https://www.sciencedirect.com/science/article/pii/S2238785417305574?via%3Dihub#bib0040 |issn=2238-7854|doi-access=free |hdl=10498/38755 |hdl-access=free }}</ref> However, unlike Rotary friction welding, it does not require either of the parts to be rotated. Instead a ring is used to generate the necessary heat by rotating it around the pipes.<ref>{{cite patent |country=AU |number=727311 |inventor=Hutt, Graham Anthony |invent1=Graham Anthony Hutt |gdate=2000-12-07}}</ref>
===Linear friction welding=== Linear friction welding (LFW) is the act of moving a single component in a linear reciprocating motion across the face of a stationary component.<ref>{{cite web |title=What is Linear Friction Welding? |url=https://www.twi-global.com/technical-knowledge/faqs/faq-what-is-linear-friction-welding |work=TWI }}</ref>
=== Friction stir welding === {{Main|Friction stir welding}} thumb|Friction stir welding Friction stir welding (FSW) is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material.<ref>{{cite web |title=What is Friction Stir Welding (FSW)? - Process and Applications |url=https://www.twi-global.com/technical-knowledge/faqs/faq-what-is-friction-stir-welding |work=TWI }}</ref> Heat is generated by friction between the rotating tool and the workpiece material, which leads to a softened region near the FSW tool. While the tool is traversed along the joint line, it mechanically intermixes the two pieces of metal and forges the hot and softened metal by the mechanical pressure which is applied by the tool.
===Friction surfacing=== {{Main|Friction surfacing}} Friction surfacing is a process derived from friction welding where a coating material is applied to a substrate. A rod composed of the coating material (called a mechtrode) is rotated under pressure, generating a plasticized layer in the rod at the interface with the substrate.
==Thermoplastic technique==
===Linear vibration welding=== {{Main|Linear vibration welding}} In linear vibration welding, the materials are placed in contact and put under pressure. An external vibration force is then applied to slip the pieces relative to each other, perpendicular to the pressure being applied.
===Orbital friction welding=== Orbital friction welding is similar to spin welding, but uses a more complex machine to produce an orbital motion in which the moving part rotates in a small circle, much smaller than the size of the joint as a whole.
== Method list connected to friction welding ==
* Forge welding * Friction stir welding (FSW)<ref name=":162"/> * Friction stir spot welding (FSSW)<ref name=":102">{{cite journal |last1=Lacki |first1=P. |last2=Kucharczyk |first2=Z. |last3=Śliwa |first3=R.E. |last4=Gałaczyński |first4=T. |title=Effect of Tool Shape on Temperature Field in Friction Stir Spot Welding |journal=Archives of Metallurgy and Materials |date=June 2013 |volume=58 |issue=2 |pages=595–599 |doi=10.2478/amm-2013-0043 |doi-access=free }}</ref> * Linear friction welding (LFW)<ref name=":13">{{cite journal |last1=McAndrew |first1=Anthony R. |last2=Colegrove |first2=Paul A. |last3=Bühr |first3=Clement |last4=Flipo |first4=Bertrand C.D. |last5=Vairis |first5=Achilleas |title=A literature review of Ti-6Al-4V linear friction welding |journal=Progress in Materials Science |date=March 2018 |volume=92 |pages=225–257 |doi=10.1016/j.pmatsci.2017.10.003 |doi-access=free }}</ref><ref name=":0" /> * Friction welding of pipeline girth welds (FRIEX)<ref name=":122">{{cite journal |last1=Pissanti |first1=Daniela Ramminger |last2=Scheid |first2=Adriano |last3=Kanan |first3=Luis Fernando |last4=Dalpiaz |first4=Giovani |last5=Kwietniewski |first5=Carlos Eduardo Fortis |title=Pipeline girth friction welding of the UNS S32205 duplex stainless steel |journal=Materials & Design |date=January 2019 |volume=162 |pages=198–209 |doi=10.1016/j.matdes.2018.11.046 |doi-access=free }}</ref> * Friction hydro pillar overlap processing (FHPPOW)<ref>{{cite journal |last1=Buzzatti |first1=Diogo Trento |last2=Chludzinki |first2=Mariane |last3=Santos |first3=Rafael Eugenio dos |last4=Buzzatti |first4=Jonas Trento |last5=Lemos |first5=Guilherme Vieira Braga |last6=Mattei |first6=Fabiano |last7=Marinho |first7=Ricardo Reppold |last8=Paes |first8=Marcelo Torres Piza |last9=Reguly |first9=Afonso |title=Toughness properties of a friction hydro pillar processed offshore mooring chain steel |journal=Journal of Materials Research and Technology |date=May 2019 |volume=8 |issue=3 |pages=2625–2637 |doi=10.1016/j.jmrt.2019.04.002 |doi-access=free |hdl=10498/38758 |hdl-access=free }}</ref> * Friction hydro pillar processing (FHHP)<ref>{{cite journal |last1=Buzzatti |first1=Diogo Trento |last2=Buzzatti |first2=Jonas Trento |last3=Santos |first3=Rafael Eugenio dos |last4=Mattei |first4=Fabiano |last5=Chludzinski |first5=Mariane |last6=Strohaecker |first6=Telmo Roberto |title=Friction Hydro Pillar Processing: Characteristics and Applications |journal=Soldagem & Inspeção |date=September 2015 |volume=20 |issue=3 |pages=287–299 |doi=10.1590/0104-9224/si2003.04 |doi-access=free |hdl=10183/132809 |hdl-access=free }}</ref> *Linear vibration welding *Spin welding of polymers * Low force friction welding<ref name=":3" />
== Other information ==
=== Welds tests for friction welding and description of zones === {{Main|Weld tests for friction welding}}
Quality requirements of welded joints depend on the form of application, e.g. in the space or flight industry, weld errors are not allowed.<ref name=":14">{{Cite book|first1=J.|last1=Pilarczyk|first2=A.|last2=Piotr|title=Poradnik inżyniera 1 – spawalnictwo|publisher=Wydawnictwo WNT|year=2013|location=Warszawa|language=pl}}</ref> Weld quality tests assurance is performed, with measurements and numerical methods.
For example, an ultra-fine grain structure of alloy or metal which is obtained by techniques such as severe plastic deformation<ref>{{cite book |last1=Rosochowski |first1=Andrzej |title=Severe Plastic Deformation Technology |date=2013 |publisher=Whittles Publishing |isbn=978-1-84995-119-7 |oclc=968912427 }}{{pn|date=December 2024}}</ref> is desirable, and not changed by the high temperature, a large heat affected zone is unnecessary.<ref>{{cite journal |last1=Skowrońska |first1=B. |last2=Chmielewski |first2=T. |last3=Pachla |first3=W. |last4=Kulczyk |first4=M. |last5=Skiba |first5=J. |last6=Presz |first6=W. |title=Friction Weldability of UFG 316L Stainless Steel |journal=Archives of Metallurgy and Materials |date=17 June 2019 |pages=1051–1058 |doi=10.24425/amm.2019.129494 |doi-access=free }}</ref><ref name=":0">{{cite journal |last1=Orłowska |first1=Marta |last2=Olejnik |first2=Lech |last3=Campanella |first3=Davide |last4=Buffa |first4=Gianluca |last5=Morawiński |first5=Łukasz |last6=Fratini |first6=Livan |last7=Lewandowska |first7=Małgorzata |title=Application of linear friction welding for joining ultrafine grained aluminium |journal=Journal of Manufacturing Processes |date=August 2020 |volume=56 |pages=540–549 |doi=10.1016/j.jmapro.2020.05.012 |doi-access=free |hdl=10447/421431 |hdl-access=free }}</ref>
In addition to changing the grain structure during metal joining cycles, by methods where high temperature affected zone was occur, are phase transformations structure. For example, in steel between austenite, ferrite, pearlite, bainite,<ref>{{cite journal |last1=Parzych |first1=S. |last2=Krawczyk |first2=J. |title=The Influence of Heat Treatment on Microstructure and Tribological Properties of Resistance Butt Welds Made of a Cast Bainitic Steel |journal=Archives of Metallurgy and Materials |date=2012 |volume=57 |issue=1 |doi=10.2478/v10172-012-0020-9 |doi-access=free }}</ref> cementite, and martensite, (See: Iron-carbon phase diagram).{{citation needed|date=March 2021}} In order to avoid changes, solid state welding may be desired and large heat affected zone is not needed if weakens the material properties.
==== Heat and mechanical affected zones in friction weld ==== thumb|Picture shows weld zones in friction welding.<ref name=":13" /> Technically, the WCZ and the TMAZ are both "thermo-mechanically affected zones"; due to the different microstructures they possess, they are often considered separately. The WCZ experiences significant dynamic recrystallisation (DRX), the TMAZ does not. The material in HAZ is not deformed mechanically but is affected by the heat. The region from one TMAZ/HAZ boundary to the other is often referred to as the "TMAZ thickness" or the plastically affected zone (PAZ).<ref>{{cite journal |last1=McAndrew |first1=Anthony R. |last2=Colegrove |first2=Paul A. |last3=Bühr |first3=Clement |last4=Flipo |first4=Bertrand C.D. |last5=Vairis |first5=Achilleas |title=A literature review of Ti-6Al-4V linear friction welding |journal=Progress in Materials Science |date=March 2018 |volume=92 |pages=225–257 |doi=10.1016/j.pmatsci.2017.10.003 |doi-access=free }}</ref>
Zones:
* WCZ– weld center zone * HAZ – heat affected zone * TMAZ – Thermo-mechanically affected zone * BM – base material, parent material * Flash
Similar terms are used in welding.
=== Seizure resistance === Friction welding may unintentionally occur at sliding surfaces like bearings. This happens in particular if the lubricating oil film between sliding surfaces becomes thinner than the surface roughness, which may be due to low speed, low temperature, oil starvation, excessive clearance, low viscosity of the oil, high roughness of the surfaces, or a combination thereof.<ref>{{cite web |last1=Kopeliovich |first1=Dmitri |title=Requirements to engine bearing materials [SubsTech] |url=https://www.substech.com/dokuwiki/doku.php?id=requirements_to_engine_bearing_materials |work=SubsTech }}{{self-published inline|date=December 2024}}</ref>
The seizure resistance is the ability of a material to resist friction welding. It is a fundamental property of bearing surfaces and in general of sliding surfaces under load.
=== Curiosities ===
* Frictional welding (micro friction stir welding) was also performed using a CNC machine.<ref>{{cite journal |last1=Wang |first1=Kaifeng |last2=Khan |first2=Haris Ali |last3=Li |first3=Zhiyi |last4=Lyu |first4=Sinuo |last5=Li |first5=Jingjing|author5-link=Jingjing Li |title=Micro friction stir welding of multilayer aluminum alloy sheets |journal=Journal of Materials Processing Technology |date=October 2018 |volume=260 |pages=137–145 |doi=10.1016/j.jmatprotec.2018.05.029 |doi-access=free }}</ref> which does not mean that it is safe and recommended for the milling machine. * Friction welding has also been shown to work on wood.<ref>{{Citation|title=Wood Welding, How is it possible? Youtube link| date=14 September 2020 |url=https://www.youtube.com/watch?v=5zGVwfVPwns |archive-url=https://ghostarchive.org/varchive/youtube/20211212/5zGVwfVPwns| archive-date=2021-12-12 |url-status=live|language=en|access-date=2021-04-06}}{{cbignore}}</ref><ref>{{Cite web|title=TWI Develops Wood Welding Process|url=https://www.twi-global.com/media-and-events/press-releases/2019/twi-develops-wood-welding-process|access-date=2021-04-06|website=www.twi-global.com|language=en-GB}}</ref><ref>{{cite journal |last1=Li |first1=Suxia |last2=Zhang |first2=Haiyang |last3=Shu |first3=Biqing |last4=Cheng |first4=Liangsong |last5=Ju |first5=Zehui |last6=Lu |first6=Xiaoning |title=Study on the Bonding Performance of the Moso Bamboo Dowel Welded to a Poplar Substrate Joint by High-Speed Rotation |journal=Journal of Renewable Materials |date=2021 |volume=9 |issue=7 |pages=1225–1237 |doi=10.32604/jrm.2021.014364 |doi-access=free }}</ref>
==References== {{Reflist}}
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