Principle of Ultrasonic Plastic Welding

Principle of Ultrasonic Plastic Welding – Cheersonic

When ultrasonic waves act on the thermoplastic plastic contact surface, it will produce tens of thousands of high-frequency vibrations per second. This kind of high-frequency vibration with a certain amplitude will transmit the ultrasonic energy to the welding area through the upper weldment. Because the welding area is two The acoustic resistance at the welding interface is large, so local high temperature will be generated. In addition, due to the poor thermal conductivity of the plastic, it cannot be distributed in time for a while, and it gathers in the welding area, causing the contact surface of the two plastics to melt rapidly, and after a certain pressure is applied, they are merged into one. After the ultrasonic stops, let the pressure continue for a few seconds to make it solidify and shape, so that a strong molecular chain is formed to achieve the purpose of welding, and the welding strength can be close to the strength of the raw material.

The quality of ultrasonic plastic welding depends on three factors: the amplitude of the transducer’s welding head, the applied pressure and the welding time. The welding time and welding head pressure can be adjusted, and the amplitude is determined by the transducer and the horn. There is a suitable value for the interaction of these three quantities. When the energy exceeds the suitable value, the melting amount of the plastic is large, and the welded material is easy to deform; if the energy is small, it is not easy to weld firmly, and the applied pressure cannot be too large. This optimal pressure is the product of the side length of the welded part and the optimal pressure per 1mm of the edge.