Introduction to Ultrasonic Welding
Ultrasonic welding adopts ultrasonic plastic welding technology, which converts high-frequency electrical energy into mechanical vibration energy through ultrasonic transducers, and then transmits the mechanical vibration energy to the welding head after changing its amplitude through a banner device. When the welding head approaches the surface of the processed product, ultrasonic waves are automatically generated, causing micro amplitude high-frequency vibration on the surface of the processed product. Friction with the surface of the processed product is converted into heat, which melts the processed product before fusion. Due to the spot welding operation, welding is relatively more perfect, and different welding effects can be obtained by replacing the welding head.
How does ultrasonic welding work?
When ultrasonic vibration hits a material (such as plastic), molecular chains begin to oscillate. The molecules begin to move and rub against each other. This generates energy (known as frictional heat). For thermoplastic materials, this process can cause them to start melting. Ultrasonic welding utilizes this principle. After a brief holding time under additional pressure, various materials (components) can be welded together at the molecular level in the connecting area.
What is ultrasonic welding suitable for?
Ultrasonic welding occurs within seconds without the need for any auxiliary tools such as adhesives or screws. Ultrasound is used in the manufacturing of packaging, automotive parts, toys, etc., for example, by:
1. Connecting injection molded parts (such as toys)
2. Embedded membranes (such as filter membranes used in medical components)
3. Integrating leather, non-woven fabrics, and textiles (such as air filters in cars)
4. Stacking different types of materials together (e.g. for airbags)
5. Use forming techniques to create connectors with shape fits (such as magnetic contacts in chargers)
6. Countersunk socket and magnet (such as encapsulated magnet for activating sensors)
Ultrasonic welding system:
The complete ultrasonic welding system consists of various components. Active components generate vibration, transmit vibration, and apply it to welded joints. The passive components absorb the force generated and fix the components in appropriate positions, especially at the welded joint points where the supporting components are connected together.
Components:
Ultrasonic generator
Ultrasonic transducer
Ultrasonic amplitude lever
Ultrasonic tool head
The combination of transducers, amplitude rods, and ultrasonic generators forms a so-called stack.
Process Technology: Energy Focusing Principle:
In order to accurately melt the components, it is necessary to concentrate the vibration energy at one point. This is called energy focusing. This specific point is the place where heat development is strongest and melting occurs - defined as a low-energy welding process.
Types of Energy Focusing:
Everything is a matter of shape: in order for vibration energy to converge at the correct point, the geometric shape of the parts or tools to be welded must be designed accordingly. For component integration focusing, an energy director (ED) focuses energy on the material itself. For the geometric shape of the focusing tool, the shape of the tool is suitable for a specific application.
What materials can be welded using ultrasonic waves?
Generally speaking, most thermoplastic materials (plastics that can be formed by heating) can be welded using ultrasonic waves. The harder the material, the better. In addition to plastic, different non-ferrous metals such as aluminum, nickel, brass, and copper are also suitable for ultrasonic welding.
