Whenever the ultrasonic wave acts 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. The acoustic resistance at the interface of the two welds is large, so local high temperatures are 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.

     Therefore, different tool heads are required for different welding objects. Due to the different use occasions and welding materials, the welding size of the ultrasonic plastic welding machine is different, and the specifications are also various.

     The output power, oscillation frequency, and amplitude range of the ultrasonic welding machine should be considered according to the material of the workpiece, the area of the welding wire, whether there are electronic components in the workpiece, and whether it is airtight or not. Misunderstood that the greater the power, the better. This is also a misunderstanding. If you don’t know much about ultrasound. It is best to consult a regular ultrasonic production plant engineering and technical personnel. If possible, it is best to collude with the manufacturer on site, and do not blindly follow the misleading of some informal ultrasound sales staff. At present, companies that produce related equipment are particularly mixed, most of which are family-style workshops, mimicking circuits mechanically, and they don't understand the working principle. The imitated equipment has the following fatal flaws. One is that the quality of externally purchased metamaterials cannot be guaranteed, and the second is that the core technology of the production process is not mastered. The equipment often exhibits instability when working at medium power and high power, and the product qualification rate is low. Sometimes the equipment is damaged. Such as the power transformer driving the transducer, the parameters of the magnetic material used cannot be measured.

There is a considerable number of people who have been engaged in ultrasonic welding for many years. There is a misunderstanding about the transmission of ultrasonic energy. They think that sound waves are welding on the contact surface. In fact, this is a misunderstanding. The real welding principle is: the transducer converts electrical energy into machinery Later, through the material molecules of the workpiece for conduction, the acoustic resistance of the sound wave in the solid is much smaller than the acoustic resistance in the air. When the sound wave passes through the joint of the workpiece, the acoustic resistance in the gap is large, and the thermal energy generated is quite large. Temperature first The capacity point of the workpiece is reached, and a certain pressure is added to make the seam weld. The other parts of the workpiece will not be welded due to low thermal resistance and low temperature. The principle is similar to Ohm's law in electrical engineering.