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   ¸¶Âû¿ëÁ¢(ؤóÍéÂïÈ; friction welding)

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Friction welding(FW) is a class of solid-state welding processes that generates heat through mechanical friction between a moving workpiece and a stationary component, with the addition of a lateral force called "upset" to plastically displace and fuse the materials. Technically, because no melt occurs, friction welding is not actually a welding process in the traditional sense, but a forging technique. However, due to the similarities between these techniques and traditional welding, the term has become common. Friction welding is used with metals and thermoplastics in a wide variety of aviation and automotive applications.

Benefits
The combination of fast joining times of the order of a few seconds, and the direct heat input at the weld interface, gives rise to relatively small heat affected zones. Friction welding techniques are generally melt-free, which offers the advantage of avoiding grain growth in engineered materials such as high-strength heat-treated steels. Another advantage is that the motion tends to "clean" the surface between the materials being welded, which means they can be joined without as much prior preparation. During the welding process, depending on the method being used, small pieces of the "plastic" metal will be forced out of the working mass in rippled sheets of metal known as "flash". It is believed that the flash carries away debris and dirt.
Another advantage of friction welding is that it allows dissimilar materials to be joined.This is particularly useful in the aerospace field, where it is used to join lightweight aluminum stock to high-strength steels. Normally the wide difference in melting points of the two materials would make it impossible to weld using traditional techniques, and would require some sort of mechanical connection instead (bolts, etc.). Friction welding provides a "full strength" bond with no additional weight. Another common use for these sorts of bi-metal joins is in the nuclear industry, where copper-steel joints are common in the reactor cooling systems.
Friction welding is also used with thermoplastics, which act in a fashion analogous to metals under heat and pressure. The heats and pressures used on these materials are much lower than on metals, but the technique can be used to join metals to plastics with the metal interface being machined. For instance, the technique can be used to join eyeglass frames to the pins in their hinges. The lower energies and pressures used allows for a wider variety of techniques to be used.

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