FSW can deliver stronger, cleaner and more efficient weld results in the right applications.
Friction stir welding (FSW) is a solid-state joining technique that has transformed the manufacturing landscape since its inception in the early 1990s. This eco-friendly and highly efficient process, known for creating high-strength welds without melting the workpiece, has found widespread applications across various industries, including aerospace, automotive, and shipbuilding. Among the companies at the forefront of advancing FSW technology is Stirweld, which has carved a niche for itself by providing cutting-edge FSW tools and solutions. Stirweld provides unconventional welding solutions to businesses seeking to leverage the numerous benefits of FSW.
According to Stirweld CEO Laurent Dubourg who presented during a January webinar, the economic and operational advantages of FSW are manifold. It’s characterized by its low welding costs, attributed to minimal consumables with the tool being the sole consumable, boasting a substantial lifetime of approximately 1000 meters.
“The process achieves high productivity rates, with welding speeds reaching up to three meters per minute,” said Dubourg. “FSW simplifies the welding setup by eliminating the need for surface preparation, such as cleaning or the use of shielding gases. For designers, this method opens up a plethora of possibilities, allowing the welding of various aluminum types, including those with high porosity, making it an ideal choice for crafting leak-proof assemblies.”
The mechanical strength of welds produced via FSW is high, often yielding joints twice as strong as those created by conventional fusion welding, with a joint efficiency of about 70%, a significant improvement over the 40 to 50% typically seen in fusion welding.
In the realm of friction stir welding, the tool plays a pivotal role, comprising two critical components: the shoulder and the pin. The shoulder is responsible for generating heat through friction, softening the material, while the pin delves into the heart of the workpiece, meticulously blending the materials to forge a seamless weld.
Heat generation in friction stir welding is a finely orchestrated process, predominantly fueled by the tool’s shoulder friction against the material surface. This frictional warmth softens the aluminum, setting the stage for the pin to merge the materials with precision, ensuring a robust and uniform weld.
“The selection of the right tool is paramount in friction stir welding, given the diverse nature of applications,” said Dubourg. “We offer a comprehensive catalog of standardized tools, each designed to cater to specific welding needs. Our ability to produce these tools on a grand scale allows us to offer unparalleled quality at competitive prices, reflecting our commitment to excellence and affordability in welding solutions.”
Stirweld introduced its advanced FSW Heads, marking a new era in the integration of friction stir welding with CNC machining. At the heart of Stirweld’s lineup is the Standard FSW Head, designed for seamless integration with 3, 4, or 5-axis CNC machines. This head offers a suite of features designed to improve the quality and efficiency of welding operations. Its universal compatibility means it can enhance virtually any machining center, transforming it into a high-performance welding unit capable of executing precise, high-quality friction stir welds.
The Standard FSW Head by Stirweld is designed for performance and reliability. It is equipped with precise force control and real-time tracking to ensure consistent tool penetration and high-quality welds, adhering to ISO 25239 standards and minimizing common welding defects. The head’s innovative cooling system, utilizing both water and air, not only secures superior weld quality but also extends the tool’s lifespan. Additionally, a specially designed coupling effectively shields the welding process from forces and vibrations, safeguarding both the weld integrity and the machinery. Technical highlights include the capability to manage weld quality across a range of 1 to 18 kN, achieve welding rotation speeds of up to 3500 RPM, and facilitate quick tool changes through the Whistle Notch system. Integration with a control interface for direct computer connections and the promise of free software updates ensure that the system remains cutting-edge.
Beyond the Standard FSW Head there’s also the FSW Head with Retractable Pin and the Smart FSW Head. The retractable pin technology is helpful, particularly for sectors like aerospace, where it addresses the challenge of exit hole elimination at the end of the welding process. This feature not only enhances the aesthetic and structural integrity of the weld but also significantly reduces post-weld processing time. The intuitive human-machine interface ensures that operators can achieve perfect control over the welding process, resulting in higher weld quality every time.
The Smart FSW Head represents a fusion of Stirweld’s Standard FSW Head’s reliability with advanced human-machine interface technology. This integration facilitates a seamless flow of welding data, making it easier for businesses to incorporate the welding process into their Enterprise Resource Planning (ERP) systems. With features like enhanced force and temperature control, real-time usage tracking, and critical data retention, this head is equipped to deliver precision and efficiency unparalleled in FSW operations. The capability for precise weld temperature measurements further elevates its performance, ensuring that each weld is executed with the utmost accuracy.
For all its benefits, FSW does come with some other pitfalls. Unsuccessful welds can result in a burr at the weld edges, porosity along the weld, lack of penetration at the weld root, and a hooking defect.
“The main limitation of friction stir welding is the gap bridging—speed is one meter per minute for FSW compared to three meters per minute for arc welding, but the distortion of the material is lower,” said Dubourg.
With a mission deeply rooted in enhancing operational efficiencies through advanced, yet cost-effective solutions, Stirweld is democratizing FSW technology. This initiative is breaking the long-standing barrier where, since its inception in 1995, FSW was predominantly confined to high-value sectors. Stirweld’s innovative approach and adaptable solutions are designed to broaden the technology’s application, making it accessible and affordable for a diverse range of industries.
Stirweld’s values—innovation, ecological responsibility, workplace satisfaction, ethical practices, and global outreach—not only define Stirweld’s identity but also underscore its commitment to not just being a participant in the industry but a catalyst for change. Stirweld’s initiatives range from boosting eco-mobility and advancing hydrogen mobility to promoting sustainable practices like local manufacturing and extending the lifecycle of CNC machines. Through educational empowerment and making FSW technology as accessible as 3D printing, Stirweld is leading the charge in global FSW innovation.
FSW represents a significant leap forward in the quest for sustainable industrial practices, particularly in the welding sector. Its adoption brings a host of benefits that align with the goals of companies prioritizing efficiency, precision, and environmental stewardship. FSW’s high Technology Readiness Level (TRL) of 9 underscores its reliability and advanced nature, making it a trusted choice for joining materials like aluminum and copper while preserving their mechanical properties. This aspect is crucial for industries reliant on these materials for their high-performance applications.
The versatility of FSW makes it capable of welding high-strength aluminum series such as 2000, 6000, and 7000, and enabling mixed material joins. This opens up new possibilities in manufacturing and engineering, where diverse material combinations are often required for innovative designs. The process’s eco-friendly nature further sets it apart; FSW eliminates the need for pre-weld cleaning, wire feeding, and shielding gases, thereby reducing the environmental impact associated with traditional welding methods. The absence of harmful emissions and noxious fumes during the welding process underscores FSW’s role in promoting cleaner, more sustainable industrial operations.
Perhaps one of the most distinctive features of FSW is its “cold welding” technique, which relies on mechanical deformation rather than melting. This approach minimizes the risk of porosity and other defects that can compromise the integrity of the weld. By adopting FSW, companies not only embrace a technology that enhances their operational efficiency and product quality but also contribute to a more sustainable and environmentally responsible manufacturing landscape.
FSW is a sophisticated process that melds precision with innovation, offering promising weld quality and strength. The journey begins with the meticulous preparation of the components, which are either aligned edge-to-edge for butt welding or overlapped for lap welding. Secure clamping is crucial to keep the materials stationary, ensuring the integrity of the weld. At the heart of FSW lies the specialized tool, comprising a rotating shoulder and pin. The shoulder generates heat through friction to soften the material around the joint, while the pin, plunged into the material, stirs the softened area, facilitating the blend without melting the components.
As the tool embarks on its path, a brief thermal stabilization phase ensures the materials reach the optimal malleable state. The tool’s movement, ranging from 700 to 3000 mm/min depending on the material’s characteristics, is critical for maintaining consistent heat and ensuring a homogeneous mix. Once the weld is complete, the tool is withdrawn, leaving an exit hole that, despite appearing as a flaw, can be addressed with various finishing techniques to achieve a smooth and flawless weld.
Understanding the nuances of FSW parameters is key to mastering the process. The tool’s geometry is tailored to the materials and desired outcomes, while the applied vertical force, rotation speed, and feed rate are calibrated to ensure effective material blending and optimal weld quality. FSW’s adaptability is evident in its configurations, with butt welding offering a seamless joint ideal for applications requiring aesthetic continuity and structural integrity. Lap welding, conversely, provides a robust bond for materials of varying types or thicknesses, making it suitable for demanding applications where strength and thermal properties are critical.
