Know about FSW| Application of new energy

Friction stir welding, also known as FSW, is a new solid phase connection technology invented by the American Welding Institute in 1991 under the combined action of mechanical force and friction heat. Although this technology started late, it quickly drew the attention of major manufacturers due to its excellent environmental protection and welding capabilities.

In the process of FSW, a cylindrical stirring head with a special shaft shoulder and needle protrusion will rotate and slowly insert into the workpiece to be welded. Through intense stirring, friction and pressure, the metal material of the weld will be plastically softened. When the stirring head rotates and moves forward, the thermoplastic metal material will be transferred from the front of the stirring head to the rear, and will be rubbed and forged under the action of the stirring shaft shoulder, and finally turns to a fine forged tissue joint. It makes full use of frictional heat and prevents severe drmation of the heated metal material by means of pressure, and quickly “bonds” two pieces of metal together, ingeniously combine heating and pressing methods.、

Currently, it can be used in the manufacture of a variety of auto parts, such as wheel hubs, rear axles, aluminum alloy battery trays, engine casing linings, side lining reinforcements, door reinforcement structural parts, large extrusion parts bonding, etc.

Ford, BMW, Fiat, GM, Mercedes-Benz and Volvo have all been involved for these components. But this technology is mainly developed independently by suppliers, or jointly developed by suppliers and car companies like its scope of use. In terms of technical reserves, suppliers are still dominant.

As we all know, light alloys such as aluminum and magnesium alloys have disadvantages of severe joint softening, easy formation of oxide film, generation of pores and thermal cracks and serious welding deformation during welding— FSW can exactly solve this kind of problem. As early as 2005, it was used on the 2005 Ford GT to weld magnesium and aluminum alloys. It can be said that friction welding is one of the most suitable welding processes for aluminum alloy materials.

1. Advantages of FSW

To reduce vehicle weight while ensuring rigidity, strengthening elements (such as Mg) are often added to aluminum alloys. Due to the high arc welding temperature of laser welding, the strengthening elements are easy to burn out, the strength of the weld seam and the performance of the vehicle will be affected, while friction welding with a lower welding temperature does not have this problem. The process of  laser welding  is difficult, and the quality is prone to repetition.

2. The improvement space of friction welding

FSW is not an absolutely perfect welding method. For example, speed is a big problem. Generally speaking, the speed of this welding method is about 100mm/min while the speed of laser welding that can also realize continuous welding is around 3000mm/min.

To mention the latest developments, the most exciting thing is the latest research from the Pacific Northwest National Laboratory (PNNL) of the Department of Energy. Through cooperation with General Motors, Alcoa and Timken (TWB), The speed of FSW has been increased by as much as 10 times, greatly reducing production time and cost, and at the same time, lighter and stronger parts have been obtained. According to reports, the improved process can reduce the weight of the door by 62%, while the cost can be reduced by 25%.

3. Conclusión

At this time, FSW is still an emerging technology, the penetration rate is not very high. However, as light weight has become a consensus, aluminum-magnesium alloy materials have received unprecedented attention, which will inevitably lead to the sudden emergence of friction welding technology.

In addition, with the increasing awareness of environmental protection, green car manufacturing technologies such as water-based coatings, intermediate coating processes, and friction welding will gradually replace laser welding, cavity wax injection, and thick car paint, etc. A fresh wave of technology.

 

From: http://www.essebinet.com/