Ultrasonic plastic welding technology

Ultrasonic plastic welding technology
Plastic is a very common material, which is widely used in all walks of life. In order to meet the requirements of plastic product assembly, ultrasonic welding technology has been developed at home and abroad.
Principle of ultrasonic plastic welding
When the vibration of an object exceeds a certain frequency, that is, above the upper limit of the hearing threshold of the human ear, such sound waves are called ultrasound. Ultrasonic plastic welding is to use the characteristics of ultrasonic transmission in the medium. The ultrasonic high-frequency vibration of 20-40kHz is transmitted to the plastic parts to be welded through the welding head, causing impact friction between the surfaces of the plastic parts and between the internal molecules, resulting in the temperature rise at the interface between the two surfaces of the plastic parts. When the temperature reaches the melting point of the plastic at the interface, the plastic melts rapidly and fills the gap between the interfaces; When the ultrasonic vibration stops, the temperature at the interface will drop. Under a certain pressure, the plastic between the gaps will change from molten state to solid state, and the two surfaces will be firmly integrated to complete the welding.
Advantages of ultrasonic plastic welding
Plastic welding has the following advantages:
No adhesive is required;
The bonding process can be completed instantly;
It will not be affected by welding heat except the bonding part;
The welding operation is convenient without danger;
Because no solvent is used, environmental pollution is avoided.
Precautions for ultrasonic plastic welding
1. The contact between the welding head and the plastic surface must be good, otherwise it will cause vibration loss and surface damage. At that time, it is necessary to insert plastic film between the welding head and the plastic surface to improve the contact.
2. Plastic parts must be firmly fixed with clamps to avoid the gap between plastic parts and clamps caused by wood chips and other impurities or uneven surface of plastic parts. If there is a gap, it can be padded with soft elastic materials such as rubber, polyurethane or polyethylene film.
3. The welding speed is determined according to the test. If the weld needs to bear a large load, the welding speed should be slightly slower.