Ultrasonic welding works on the basic principle of energy of ultrasonic wave. It’s the process of connecting two parts together to form a finished component.This process relies on the high frequency ultrasonic vibrations produced and applied to the parts through the horn. These vibrations are generated by the ultrasonic system, which sends an alternating current. The ultrasonic energy melts the contact point between the two parts, creating a joint. Ultrasonic welding technology generally is known and is essentially a solid state bonding process carried out at ambient temperature, without the aid of solders or fluxes.
Ultrasonic welding machine principle
Ultrasonic welding machine principle

Ultrasonic Welding Step by Step

The basic process of ultrasonic welding can be described by the following steps:

  1. The parts to be welded are placed in the anvil or fixture.
  2. The horn contacts the parts to be welded.
  3. Pressure is applied to keep the horn in contact with the welded materials and to hold them together.
  4. The horn delivers ultrasonic vibrations to heat up the materials. The vibrations move less than a millimeter either up-and-down or side-to-side.
  5. The materials are welded together.
  6. The horn gets retracted and the welded materials can be removed from the anvil.

The welding times, applied pressures and temperatures are controlled by a computer or microprocessor within the welding apparatus. And what actually happens during the welding process depends on the nature of the materials.

How does the ultrasonic welding work

The ultrasound converter converts the electrical signal from the generator into mechanical vibrations. They, in turn, are directed to the workpiece to be welded via the booster and the sonotrode under a specific pressure.

The mechanical vibrations generate frictional heat at the defined joints of the workpiece which causes the material to melt and bonds the parts together.

During a brief cooling phase, a clamping force is applied to fuse the plasticized material. The pieces welded together with ultrasonic energy are immediately available for further processing.

Depending on the application, the sonotrodes can weld vertically, horizontally and continuously.

Ultrasonic Welding Components:

The ultrasonic vibrations are produced by a series of components, including generator(power supply), converter, booster, and horn, which ultimately transmit mechanical vibrations to the two parts that need to be welded.

Generator(Power Supply):

The ultrasonic welding needs high frequency and high voltage power supply. This power is needed by the transducer to generate vibrations.

hcsonic ultrasonic generator
hcsonic ultrasonic generator

Transducer is a device which can convert high frequency electric signal into high frequency mechanical vibration. This is connected with the welding head. The converter or piezoelectric transducer used in this welding process.

Ultrasonic transducer
Ultrasonic transducer
Booster and Horn:

The mechanical vibration created by the transducer is supplied to the booster which amplifies this vibration and supply to the horn. Horn is a device which supply this amplified vibration to the welding plates.

Ultrasonic booster and round flange
Ultrasonic booster and horn
Fixture or clamping devices:

This device is essential in the ultrasonic welding. This uses either electrical, hydraulic, pneumatic or mechanical energy to hold the plates into desire location.


  • Adopting the hot melt effect, the product has increased water resistance, lighter weight and easier folding.
  • Ultrasonic welding technology does not require flammable fuels and open flames, so compared to other welding methods, it’s a safer process.
  • The ultrasonic welding technology sets itself apart with fast welding speeds, high welding strength and good sealing performance.
  • Ultrasonic welding is aclean, efficient, and repeatable process that produces strong, integral bonds while consuming very little energy.
  • The cooling time is very quick, and the pieces do not need to remain inside the tool for a long period of time to dry or cure the welding joint.
  • Ultrasonic welding machinecan cut textiles while welding and realize automatic edge banding.
  • This type of welding is not dangerous to humans, indeed the vibration are called ultrasonic because they are at frequencies higher than those that can be heard by the human ear.
  • The welding process is clean because it doesn’t use harmful solvents or glues while also not damaging the product.
  • This ultrasonic welding technology is also easy to implement in a production process and has a low fault rate.continuous production without interruption


Ultrasonic assembly is widely accepted and is used in the automotive, medical, electrical and electronic, communications, appliance, consumer products, toys, textile and packaging industries. It is an economical process that can significantly increase production and lower assembly costs. Ultrasonic Welders can be easily integrated in automation manufacturing environment and provide unprecedented repeatability, reliability and accuracy to the process.

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