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Common mistakes in the use of ultrasonic welding machine

At present, the use of ultrasonic welding machines has become quite popular. Products packaging, cutting, riveting, embossing, drilling and other industries are all indispensable equipment. Therefore, ultrasonic welding machines with various and various functions have also emerged. , The application fields are also different, and the use methods and requirements of the equipment are very different. A large part of consumers are currently using it. Really explain these misunderstandings

1. Misunderstanding of welding principle

Many people have been engaged in ultrasonic welding for many years. There is a misunderstanding about the transmission of ultrasonic energy, that is, the sound waves are welded on the contact surface. In fact, this is a misunderstanding. The real principle of ultrasonic welding is that after the transducer converts electrical energy into mechanical energy, it is conducted by the material molecules of the workpiece. When the sound wave propagates in a solid, the acoustic resistance is much smaller than the acoustic resistance when it propagates in the air. When the sound wave passes through the gap of the workpiece, the acoustic resistance in the gap is relatively large, and the heat generated is quite large. The temperature reaches the holding point of the workpiece first, and then a certain pressure is applied to fuse the weld. Due to the small thermal resistance and low temperature of other parts of the workpiece, fusion will not occur. This principle is similar to Ohm's law in electrical engineering

2. Misunderstanding of the workpiece material:

Ultrasonic welding machines also have requirements for the material of the welding workpiece. Not all materials can be welded. Some people understand that any material can be welded, which is a big misunderstanding. Some different materials can be welded better, some can be melted, and some are not. The melting point of the same material is the same, in principle, it can be welded, but when the melting point of the workpiece is greater than 350°C, ultrasonic welding is not suitable. Because ultrasound is the instantaneous melting of workpiece molecules, the judgment basis is within 3 seconds. If the welding is not good, another welding process should be selected. For example, hot plate welding and so on. Generally speaking, ABS materials are easy to weld, and nylon has a greater degree of welding.

3. Misunderstandings in ultrasonic welding

Ultrasonic energy is an instantaneous explosion, and solder joints or beads should be formed, and the transmission distance should comply with the ultrasonic welding method. Some people think that as long as it is a plastic material, no matter how the joint surface is welded, this is also a wrong understanding. When instantaneous energy is generated, the larger the joint area, the more serious the energy dispersion, the worse the welding effect, and even the welding cannot be performed. In addition, when ultrasonic welding, the wave propagates in the longitudinal direction, and the energy loss is proportional to the distance. The welding distance should be controlled within 6cm. The welding seam should be controlled between 30-80 wire, and the thickness of the workpiece arm should not be less than 2mm, otherwise the welding will not be good, especially for products that require air tightness

4. Ultrasonic output power error

The size of the ultrasonic output power depends on the diameter, thickness, material and design process of the piezoelectric ceramic chip. Once the transducer is set, the power will be set. Measuring the magnitude of output energy is a complicated process. It is not that the larger the transducer, the more power tubes the circuit uses, the greater the output energy. It requires a rather complicated amplitude measuring instrument to measure its amplitude, because most users know too much about ultrasound, and some sales staff mislead and give consumers a wrong understanding. The amount of power consumption does not reflect the size of the output superpower, such as low longitudinal energy and large current consumption, which can only show that the efficiency of the device is low. Reactive power is high and appropriate.