Linear friction welding

Another variant of the friction welding process, linear friction welding, uses servo-hydrauHcs pumps to vibrate parts back and forth against each other. Bond areas of approximately 1000 mm can be joined the attachment of turbine blades to rotors is a prevalent apphcation of this technology. 

Valrls A, Frost M (2000) Modelling the linear friction welding of titanium blocks. Mater Sci Eng A 292(1) 8-17... 

The process parameters affecting the strength of the resulting weld are the amphtude and frequency of motion, weld pressure, and weld time. There are two types of vibration welding linear, in which friction is generated by a linear motion of the parts, and orbital, in which one part is vibrated using circular motion in all directions. Examples of these processes are illustrated in Figure 7.26. 

However, the same mechanical techniques at the interface of two solid wood surfaces in the absence of any thermoplastic material, or any other binder, yields joints of considerable strength. " The equipment used for the mechanical vibration welding of wood in the absence of an adhesive is the same type of equipment as used for frictional welding of metals. Figure 1 shows the characteristic linear vibrational movement of the type of industrial metal welding machine used, as well as the frictional shift and force applied to the two pieces of wood during welding. 

There are two types of vibration welding linear and axial. Linear vibration welding is most commonly used. Friction is generated by a linear, back-and-forth motion. Axial or orbital vibration welding allows irregularly shaped plastic parts to be vibration welded. In axial welding, one component is clamped to a stationary structure, and the other component is vibrated using orbital motion. 

In spin or vibrational welding, heating is achieved by rubbing the two surfaces together at a sufficiently high speed to melt the polymer by friction. Spin welding is suitable for circular objects, whereas vibrational welding can be achieved by either circular or linear motion. Total cycle times are of the order... 

Figure 14.28 Linear vibration welding. Part surfaces are rubbed together in a longitudinal direction, along the z axis, generating heat through friction. Processing parameters are the weld amplitude, a, the weld frequency, n, the weld pressure, p, and weld time, f. Pressure is applied along the y axis, 90° to the vibration.

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