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Ultrasonic Welding


An Overview of the Ultrasonic Welding Process

Ultrasonic welding is a process for joining dissimilar materials and plastics with the help of high frequency vibrations. Small, complex, and delicate job pieces are produced with ultrasonic welding, which are not feasible by other conventional welding techniques. Ultrasonic welding is useful only for small parts such as toys, cassettes, and watches, etc. However, no nails, connecting bolts, or adhesives are used to perform the task. In the recent past, ultrasonic welding has developed into a complete form of welding process, and is used worldwide on industry scale to get the benefits that it offers in its precision and versatility.

Ultrasonic welding equipment can be optimized according to the requirements of the material or parts to be welded. The parts to be welded are placed between a prefixed shaped nest and sonotrode, the welding tool, which is connected to a transducer is lowered, and a high frequency vibration is applied resulting in melting of contact area between two parts, and releasing the heat energy afterwards will bind the parts together. The interface between two parts is specially designed to concentrate melting process.

Ultrasonic welding-applicability to different parts

The process of ultrasonic welding is based on the principle of energy conversion, i.e., energy of vibrations is used to produce a high quality weld. Earlier the technique was applicable only to hard plastic parts; however, today, ultrasonic welding can be used both for plastic welding (rigid and less rigid) and metal parts. In fact, the advancement of ultrasonic technology has given a new boost to the sector of intricate and small pieces of work, like, watches, control systems, and other machine parts.

In general, plastic parts been welded by ultrasonic for a number of years and it is considered to be a state of the art technology. The process involves creation of heat energy required for welding by absorption of mechanical vibrations applied vertically, reflection of vibrations in the connecting area, and the friction of the parts to be welded, and application of pressure within a short span of time. The quality of the weld is uniform, which is mainly due to fact that the energy transfer and release is constant. However, it is required that both parts must have equivalent melting points.

Whereas in the case of metals, the situation is entirely different; for, unlike other processes, metals are not heated but are welded by applying mechanical vibrations. However, the vibrations are applied horizontally. Though heat is present there but it is not sufficient to melt the metal parts.

Ultrasonic Welding-components of the system

Some of the basic elements of the ultrasonic welding system are as follows:

" A press, which is used to put the parts under pressure.
" Anvil, which is used to place the parts.
" An ultrasonic stack composed of a converter, which is used to convert electrical signal into mechanical; an optional booster, modifies the amplitude of the vibration; and a sonotrode, which applies mechanical vibrations to the parts.
" A power supply
" A controller

See also hermetic welding

 Ultrasonic Welding Resources

Welding Processes
Precision Welding
Micro Welding
Laser Welding
Resistance Welding
Seam Welding
Ultrasonic Welding
Hermetic Welding
Projection Welding basics
Orbital Welding
Underwater Welding