ADVANCED WELDING TECHNOLOGIES: FSW IN AUTOMOTIVE MANUFACTURING

This introduction paper is based on the paper "ADVANCED WELDING TECHNOLOGIES: FSW IN AUTOMOTIVE MANUFACTURING" published by "International Congress Motor Vehicles & Motors 2024".

1. Overview:

• Title: ADVANCED WELDING TECHNOLOGIES: FSW IN AUTOMOTIVE MANUFACTURING
• Author: Nada Ratković, Dragan Adamović, Srbislav Aleksandrović, Vesna Mandić, Dušan Arsić, Marko Delić, Živana Jovanović Pešić
• Year of publication: 2024
• Journal/academic society of publication: 10th International Congress Motor Vehicles & Motors 2024
• Keywords: welding, friction stir welding, welded joint, automotive manufacturing, steel

2. Abstract:

The process of joining structural elements of a vehicle plays an important role in the development of new models in the automotive industry. Among the various technologies represented in the automotive industry, the friction stir welding (FSW) technology has been increasingly applied in recent times. FSW provides high-quality welded joints, has high energy efficiency, relatively simple equipment, and the possibility of process automation. It is also the most environmentally friendly technology (no harmful fumes, harmful radiation, light flashes, or protective gas atmospheres), which is of great importance for the modern automotive industry. This automated friction welding process fits well with industries that have high-volume production, such as the automotive industry. Thanks to the application of this welding process, different, new, and more complex products have already been created in the automotive industry. On the other hand, car manufacturers are increasingly working on the design of products made from mixed or hybrid materials, where it is necessary to combine and join completely different metals, such as the joining of steel and aluminium, in order to reduce the weight of their vehicles. With traditional welding methods, joining different metals was not possible. Additionally, the use of industrial robots enables the application of the FSW process for joining materials along complex joint line configurations, as well as joining sheets and plate materials in all welding positions. This paper presents the basic principles of the FSW technological process. Then, all the technological components of this welding process are described. The physical essence of the process itself is based on the interaction of an appropriate tool with the base material. The rotation of the tool through the base material ensures the release of mechanical energy as a result of intense friction and mixing of the welded material. This mechanical energy is converted into heat, which heats the material in the joining zone, thus forming a continuous, high-quality weld. The paper presents examples of the application of FSW in the automotive industry by leading global manufacturers.

3. Introduction:

Modern manufacturing demands faster, higher-quality welding processes. In the automotive and aerospace industries, there is a growing need to use lightweight metals like aluminum and magnesium to reduce component weight. Conventional joining methods such as resistance spot welding and laser spot welding have limitations, including tool wear, thermal distortion, and defects like porosity. These challenges highlight the need for innovative, efficient, and environmentally friendly welding technologies like Friction Stir Welding (FSW), which is a solid-state pressure welding process that has seen increasing application.

4. Summary of the study:

Background of the research topic:

The automotive industry is continually seeking to reduce vehicle weight to lower fuel consumption and meet environmental standards. This has led to the increased use of lightweight materials like aluminum alloys and advanced high-strength steels (AHSS). Joining these materials, especially in dissimilar combinations (e.g., steel to aluminum), poses a significant challenge for traditional welding methods, creating a need for advanced solutions.

Status of previous research:

Conventional joining technologies like resistance spot welding are widely used but suffer from drawbacks such as high energy consumption, tool degradation, and thermal distortion. Other methods like laser welding can introduce defects. This has driven research and development into alternative solid-state joining processes, with Friction Stir Welding (FSW) and its spot-welding variant (FSSW) emerging as promising solutions due to their ability to produce high-quality joints without melting the base material.

Purpose of the study:

This paper aims to provide a comprehensive overview of Friction Stir Welding (FSW) technology. It presents the fundamental principles of the FSW and FSSW processes, describes the key technological components and parameters, and illustrates its practical application in the automotive industry with examples from leading global manufacturers.

Core study:

The study explains that FSW is a solid-state joining process where a non-consumable rotating tool is plunged into the interface of two workpieces. The friction between the tool and the material generates heat, plasticizing the material, which is then mechanically stirred and forged by the tool's profile to create a high-integrity bond. The paper details several variants, including:

• Friction Stir Spot Welding (FSSW): A localized spot weld is created without linear tool movement.
• Refill FSSW (RFSSW): An advanced variant using a two-part tool (probe and sleeve) that moves independently to create a spot weld without the "exit hole" typically left by conventional FSSW tools (Figure 2, Figure 3).
• Swept FSSW: A process where the tool performs a complex rotational movement along a circular path to create a larger mixing zone and a stronger joint (Figure 4, Figure 5).
  The study also identifies the critical process parameters—such as tool geometry, rotation speed, plunge depth, and dwell time—that govern the final quality of the welded joint.

5. Research Methodology

Research Design:

The paper is designed as a descriptive review. It synthesizes existing knowledge on FSW technology by explaining its underlying principles, classifying its variants, and reviewing its current state of application.

Data Collection and Analysis Methods:

The research is based on a review of existing scientific literature, including journal articles, conference proceedings, and publicly available technical reports. The authors analyze this information to describe the mechanics of FSW, compare its different methods, and present real-world examples and images from industrial applications in the automotive sector.

Research Topics and Scope:

The scope of this paper is focused on Friction Stir Welding (FSW) and its variants, particularly in the context of automotive manufacturing. It covers the fundamental process, the evolution to FSSW and advanced methods like RFSSW and Swept FSSW, the key process parameters and tool design, and documented applications by major car manufacturers.

6. Key Results:

Key Results:

• FSW is an advanced, energy-efficient, and environmentally friendly welding technology capable of producing high-quality joints in similar and dissimilar materials, such as aluminum and steel.
• Variants like Friction Stir Spot Welding (FSSW) are being developed to replace conventional spot welding. Advanced methods like Refill FSSW (RFSSW) have overcome the key limitation of the exit hole, producing a smooth surface finish.
• The Swept FSSW process creates a larger, stronger joint by using a complex tool path that widens the material mixing zone.
• The quality and mechanical properties of the weld are highly dependent on carefully selected process parameters, including tool rotation speed, penetration depth, dwell time, and tool geometry (Figure 6, Figure 7).
• FSW is already in use by major automotive companies like Mazda, Toyota, Ford, and others for manufacturing lightweight components such as hoods, rear doors, and body panels (Figure 9, Figure 10, Figure 11, Figure 12).

Figure Name List:

• Figure 1 FSW process scheme (a), FSSW process stages (b) [8]
• Figure 2 Schematic of the Refill FSSW process with indentation shoulder [10]
• Figure 3 Schematic of the Refill FSSW process with an indentation probe [10]
• Figure 4 Scheme of the Swept FSSW welding procedure [6]
• Figure 5 Path of tool movement in the Swept FSSW procedure [6]
• Figure 6 Tool model for FSSW in the joining process
• Figure 7 FSSW tool components: a) clamping ring, b) sleeve, c) pin [9]
• Figure 8 Robotic arm (a), tool (b), joint surface (c) [15]
• Figure 9 Example of FSW application in the automotive industry in Japan [12]
• Figure 10 FSW at the Lincoln factory [11]
• Figure 11 Application of FSW for rear doors on the Mazda RX-8 [11]
• Figure 12 Automotive components connected using the FSW procedure of the German company Inpro [11]

7. Conclusion:

The application of advanced welding technologies like FSW is growing in the automotive industry to meet the increasing demand for higher quality, more efficient, cost-effective, and environmentally friendly manufacturing. Although the FSW process is scientifically complex, involving nonlinear material flow and thermal dynamics, it offers excellent joint characteristics, including high strength and fatigue resistance. With optimal selection of parameters and tools, FSW provides superior results and is being successfully applied in the automotive sector and beyond.

8. References:

• [1] Yang, X. W., Fu, T., Li, W. Y.: Friction stir spot welding: A Review on joint macro and microstructure: Property and Process Modelling; Material Science and Engineering, vol. 6, Article ID 697170, 2014.https://doi.org/10.1155/2014/697170
• [2] Nguyen, N., Kim, D. Y., Kim, H. Y.: Assessment of the failure load for an AA6061-T6 friction stir spot welding joint, Proceedings of the Institution of Mechanical Engineers, part B:Journal of Engineering Manufacture. vol. 225, no. 10, 1746-1756, 2011.
• [3] Zou, Y., Li, W., Chu, Q., Wu, D., Su, Y., Shen, Z., Wang, F., Tang, H.: Formability and mechanical property of refill friction stir spot-welded joints. Welding in the World, vol. 65, 899-907, 2021.
• [4] Andrzej, K., Tomasz, T., Elbieta, G., Jan, S.: Investigation into the Effect of RFSSW Parameters on Tensile Shear Fracture Load of 7075-T6 Alclad Aluminium Alloy Joints, Materials vol. 14, no. 12, 3397, 2021. DOI: 10.3390/ma14123397.
• [5] Mohd, N. Y., Wan, E. W. A. R., Yupiter, H. M., Micheal, S., Muhammad, A. S., Ahmad, A. A. R.: Tensile stress-strain analysis of resistance spot weld using non-linear FEM with experimental verification, Welding and Welded Structures, vol. 1, 5-21, 2021.
• [6] Su, Z. M., He, R. Y., Lin, P. C. Dong, K.: Fatigue analyses for swept friction stir spot weds in lap-shear specimens of alclad 2024-T3 aluminium sheets. International Journal of Fatigue, vol. 61, 129-140, 2014.
• [7] Siddharth, S., Senthilkumar, T.: Study of friction stir spot welding process and its parameters for increasing strength of dissimilar joints. Revista Técnica de la Facultad de Ingeniería Universidad del Zulia, vol. 39,no 1, 168-176, 2016.
• [8] Mukuna, P.M.: Current developments in friction stir welding (FSW) and friction stir spot welding (FSSW) of aluminium and titanium alloys, Engineering Proceedings, vol. 56, no. 1, 184, 2023.
• [9] Zhikang. S., Yuguan. D., Wei. G., Wentao. H., Xiaochao. L., Haiyan. C., Fenjun. L., Wenya. L., Adrian. G.: Refill friction stir spot welding al alloy to copper via pure metallurgical joining mechanism. Journal of Mechanical Engineering, vol. 34. 75, 2021.
• [10] Belnap. R., Blackhurst. P., Hovanski. Y., Curtis. A., Cobb. J., Misak. H.: Production evaluation of refill friction stir spot welding, Friction Stir Welding and Processing XII (TMS 2023), 139-148, 2023.
• [11] Thomas. W. M., Kallee. S. W., Staines. D. G., Oaskley. P.J.: Friction stir welding-process variants and developments in the automotive industry. Paper presented at 2006 SAE World Congress, 3-7 April 2006, CoboCenter, Detroit, Michigan, USA.
• [12] Shen. Z., Lia. W.Y., Ding. Y., Hou. W., Liu. X.C., Guo. W., Chen. H.Y., Liu. X., Yang. J., Gerlich. A.P.: Material flow during refill friction stir spot welded dissimilar Al alloys using a grooved tool, Journal of Manufacturing Processes, vol. 49, 260-270,2020. https://doi.org/10.1016/j.jmapro.2019.11.029
• [13] Andres. J., Wronska. A., Gałaczynski. T., Luty. G., Burek. R.: Effect of process parameters on microstructure and mechanical properties of RFSSW lap joints of thin Al 7075-t6 sheets. Archives of Metallurgy and Materials, vol. 63, 39-43, 2018.http://dx.doi.org/10.24425/118906
• [14] Shen. J., Lage. S.B.M., Suhuddin. U.F.H., Bolfarini. C., Santos. J.F.: Texture development and material flow behavior during refill friction stir spot welding of AlMgSc, Metallurgical and Materials Transactions A, vol. 49, 241-254, 2018.http://dx.doi.org/10.1007/s11661-017-4381-6
• [15] Refill friction stir spot welding parameter development in transport industry aluminium alloys. TWI Core Research Project P31030.
• [16] Ratkovic. N., Nikolic., R., Samardzic. I.: Structural, chemical and deformation changes in friction welded joint of dissimilar steel, Metalurgija, Vol.53, No. 4, ISSN 0543-5846, 2014. Pp 513-516.

9. Copyright:

• This material is a paper by "Nada Ratković, Dragan Adamović, Srbislav Aleksandrović, Vesna Mandić, Dušan Arsić, Marko Delić, Živana Jovanović Pešić". Based on "ADVANCED WELDING TECHNOLOGIES: FSW IN AUTOMOTIVE MANUFACTURING".
• Source of the paper: [DOI URL unavailable in provided text. A relevant DOI would be inserted here, e.g., for reference [1] https://doi.org/10.1155/2014/697170]

This material is summarized based on the above paper, and unauthorized use for commercial purposes is prohibited.
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Paper Summarize:

Key questions and answers about the research:

This paper reviews the Friction Stir Welding (FSW) process, an advanced, solid-state joining technology increasingly used in the automotive industry. It details the principles of FSW and its variants, such as Friction Stir Spot Welding (FSSW), and highlights how process parameters and tool design affect joint quality. The study demonstrates FSW's real-world application by leading manufacturers for creating lightweight, high-quality vehicle components.

Q1.

What is the primary advantage of FSW over conventional welding methods in the automotive industry?

A1.

FSW is an environmentally friendly, solid-state process that produces high-quality joints without harmful fumes, radiation, or melting the base material, overcoming issues like porosity and high thermal distortion found in traditional methods. (Source: "INTRODUCTION", "ADVANCED WELDING TECHNOLOGIES: FSW IN AUTOMOTIVE MANUFACTURING")

Q2.

What problem does standard Friction Stir Spot Welding (FSSW) have, and how is it solved?

A2.

Standard FSSW leaves an exit hole after the tool is withdrawn. This is solved by a variant called Refill Friction Stir Spot Welding (RFSSW), which uses a special two-part tool to fill the hole, creating a smooth, defect-free surface. (Source: "THE FRICTION STIR WELDING PROCESS")

Q3.

How does the Swept FSSW process differ from the conventional FSSW process?

A3.

In Swept FSSW, the tool performs a complex movement, rotating on its axis while also moving along a circular path. This action mixes a larger amount of material in a wider zone, resulting in a mechanically superior joint compared to conventional FSSW. (Source: "CLASSIFICATION OF FSSW WELDING PROCESSES AND THE SFSSW PROCESS", Figure 4, Figure 5)

Q4.

What are the key parameters that control the quality of a friction stir spot weld?

A4.

The key parameters include tool penetration depth, tool rotation speed (rpm), dwell time (duration of immersion), tool plunge rate, and the axial force applied to the tool. Careful selection of these parameters is crucial to prevent defects and ensure joint integrity. (Source: "BASIC PARAMETERS OF THE PROCESS AND TOOL GEOMETRY")

Q5.

Can FSW be used to join dissimilar materials, and why is this important for automotive manufacturing?

A5.

Yes, FSW is effective for joining dissimilar materials, such as steel and aluminum. This is critical for the automotive industry's goal of creating hybrid material structures to significantly reduce vehicle weight, which in turn improves fuel efficiency and lowers emissions. (Source: "ABSTRACT", "INTRODUCTION")

Q6.

Which major automotive companies are already using FSW technology?

A6.

FSW and its variants are used by several leading global companies, including Mazda, Kawasaki, Toyota Motor, General Motors, Ford Motor, Fiat Chrysler Automobiles, and PSA Peugeot Citroen, for components like aluminum hoods, rear doors, and body panels. (Source: "APPLICATION OF FSW IN THE AUTOMOTIVE INDUSTRY")