What Is an Ultrasonic Welder?
An Ultrasonic Welder is a mechanical device that uses the heat generated by friction between objects to weld them together.
It is mainly used for joining plastic materials and dissimilar metals.
Because welding is performed by frictional heat, it consumes less power than other heating-based welding methods. It offers easy automation and ensures high reproducibility, as well as a good appearance after welding because no adhesives are used.
Developed in the 1960s, Ultrasonic Welder has been in use for over 50 years. It typically consists of an oscillator and welding table or a transducer and horn. By applying simultaneous ultrasonic vibration and pressure, this device can quickly melt and bond resin and metal materials. Ultrasonic welding machines find extensive applications across various industries. Key features of this welding machine are that it does not use any adhesives, so the appearance after welding is beautiful, it is environmentally friendly because it uses instantaneous frictional heat to weld, so it consumes less power, and its easy to automate, so it is highly reproducible.
Uses of Ultrasonic Welder
The main applications of Ultrasonic Welders are as follows:
- Joining terminals and wiring.
- Joining plastic products.
- Joining dissimilar metals such as aluminum and copper materials.
Ultrasonic welding can be used to bond metals as well as plastics. Its also used to bond metal terminals and wiring, and metal wires inside IC chips.
Principle of Ultrasonic Welder
Ultrasonic Welder is a device in which a transducer, called a horn, applies a certain amount of pressure between the materials to be bonded. The vibration of the horn transfers energy to the bonded surfaces for welding.
The frictional heat generated between the surfaces of the bonded objects makes welding possible. Especially when the object to be welded is metal, the ultrasonic vibration causes the metal surfaces to rub against each other, destroying the oxide film on the surfaces and providing bonding strength.
Ultrasonic Welders consist of an oscillator and a transducer. The oscillator is a device that generates ultrasonic vibrations and is designed to have a constant amplitude so that the amplitude does not change depending on the type of material to be welded. By keeping the amplitude constant, the quality of the product after welding can be ensured. The transducer consists of a Langevin transducer (commonly known as a BL transducer) and a horn member that transmits the vibration. Ultrasonic Welders perform welding by propagating ultrasonic waves from the horn to the welded product.
Other Information on Ultrasonic Welder
1.Features of Ultrasonic Welder
Ultrasonic Welders tend to melt the heated material if the welding time is too long, while the resin tends to carbonize if the welding time is too long. Also, the pressure generated when the object to be welded is held by the horn reduces the welding time if the pressure is high, but too much pressure can also cause the object to stop melting. The important point is to control the three factors, namely, time, pressure, and heat, and ensuring they remain within an appropriate condition range.
Advantages of Ultrasonic Welding include the following:
- Applicable to virtually all thermoplastics.
- Continuous seam joining and simultaneous multi-point joining are possible.
- Low heat storage.
- Fluxless welding eliminates the need for cleaning processes, and no sparks, flames, or smoke are generated.
- No toxic substances are emitted during plastic welding.
- No consumable parts or materials, energy saving and low running cost.
- Capable of joining dissimilar metals.
While the following points are some disadvantages:
- Shapes that cannot be sandwiched by the horn, such as miscellaneous or three-dimensional shapes, cannot be joined.
- High amplitude may result in good weldability, but depending on conditions, scratches or cracks may occur on the resin.
- High pressure may prevent welding.
2. Ultrasonic Horn
An ultrasonic horn is a component that efficiently transfers vibration energy to the object to be welded. Ultrasonic waves are converted into mechanical vibration amplitude energy by a transducer, and then amplified by a transducer called a booster before being transmitted to the horn. The amplitude is gradually amplified and then optimized at the horn tip. By concentrating the ultrasonic vibration at the horn tip, the object is impacted 40,000 times per second (at 40 kHz).
Ultrasonic horns are available in the following types:
- Step type: high amplitude and high stress type.
- Catenoidal type: intermediate in amplitude and stress.
- Exponential type: low amplitude and low stress.
Ultrasonic horn materials are used according to the purpose of welding, and the following materials are mainly used:
3. Mask Manufacturing Using Ultrasonic Welder
Ultrasonic Welders are also used in mask manufacturing. Ultrasonic welding machines use ultrasonic vibrations to melt materials and weld them together to produce the twill lines and engravings on masks. This process eliminates the need for threads and adhesives, simplifying the production process.
In addition, the mask can be welded to the mask body with ear strings made of different materials such as natural latex rubber for the rubber part and PE for the thread parts. This ensures that the mask can be manufactured with a single equipment. It is expected that the use of Ultrasonic Welders in mask production will increase in the future.