At present, the use of ultrasonic equipment to weld a variety of plastic parts has become quite popular, product packaging. Cutting. Riveting, embossing, punching, etc. is an indispensable device, so various, various functions Ultrasonic welding has also emerged, different application fields, different methods of use and equipment requirements. There are a lot of consumers in the current use. really add a note to these misunderstandings!
1) Understanding the misunderstanding of welding principle
There are quite a few people who have been engaged in ultrasonic welding for many years. There is a misunderstanding about the transmission of ultrasonic energy. It is considered that the sound wave is welded on the contact surface. In fact, this is a misunderstanding. The real welding principle is: The transducer converts the electric energy. After being mechanical, it conducts through the material molecules of the workpiece. The sound resistance of the sound wave in the solid is much smaller than that in the air. When the sound wave passes through the joint of the workpiece, the sound resistance in the gap is large, and the heat energy generated is quite large. The temperature first reaches the tolerance of the workpiece, plus a certain pressure, so that the joint is welded. The other parts of the workpiece are not welded due to the small thermal resistance, and the principle is similar to Ohm's law in electrotechnics. Br /> 2) Mistakes in workpiece materials:
Ultrasonic plastic welding machine also has requirements for the material to be welded. Not all materials can be welded. Some people understand that any material can be welded. This is a big misunderstanding. There is more between different materials. Good soldering, Some are basically capable of phase fusion, and some are not melted. The melting point of the same material is the same, The principle is that it can be welded, but when the melting point of the workpiece to be welded is greater than At 350 ° C, it is not suitable for ultrasonic welding. Because ultrasonic is the instant melting of the workpiece molecules, the judgment is based on 3 seconds, can not be well welded, you should choose other welding processes. Such as hot plate welding, etc. Generally speaking ABS material is the easiest to weld, Nylon is the most difficult to weld. Please refer to the attached table for specific welding material selection:
3) Process misunderstanding of welding workpiece
Ultrasonic energy is an instantaneous burst, the weld should be a point or a line, and the distance to be transmitted must conform to the ultrasonic welding method. Some people think that as long as it is a plastic material, no matter how the joint surface can be welded well, It is also a misunderstanding. When the instantaneous energy is generated, the larger the joint area, the more severe the energy dispersion, the worse the welding effect, or even the welding. In addition, the ultrasonic wave is longitudinally transmitted, and the energy loss is proportional to the distance. Long-distance welding should be controlled within 6 cm. · The welding line should be controlled between 30----80 filaments. The arm thickness of the workpiece should not be less than 2 mm. Otherwise, it should not be welded well, especially for airtight. Product.
4) Ultrasonic output power misunderstanding
The output power of the ultrasonic wave is determined by the diameter and thickness of the piezoelectric ceramic piece, the material, and the design process. Once the transducer is shaped, the maximum power is also fixed. Measuring the output energy is a complicated process, not a change. The larger the energy device, the more power the circuit uses and the higher the output energy. It requires a fairly complicated amplitude measuring instrument to accurately measure its amplitude. Because most users know too much about ultrasound, plus some sales. Misleading personnel give consumers a misunderstanding. The amount of power consumed does not reflect the output of super-power, If the longitudinal energy is low, and the current consumption is large, only the efficiency of the equipment is low. Power is large and convenient.
5) Ultrasonic welding machine selection error zone
How much output power is used, the oscillation frequency and the amplitude range should be considered according to the material of the workpiece, the area of the wire bond, whether there are electronic components in the workpiece, whether it is airtight or not. I mistakenly think that the bigger the power, the better. This is also a misunderstanding. If you don't know too much about ultrasound. It is best to consult the engineering and technical personnel of the regular ultrasonic production plant. If you have the conditions, it is best to go to the factory site, do not blindly listen to the misleading of some irregular ultrasound sales staff. At present, the companies that produce related equipment are particularly mixed. Most of them are family-style workshops. They are used to copy and reproduce the circuit, and they seem to understand the working principle. Imitation equipment has the following fatal flaws. The first is that the quality of the externally purchased materials cannot be guaranteed, and the core technology of the second production process is not mastered. The equipment often exhibits instability during medium power and high power operation, and the product qualification rate is low. Sometimes the device is damaged. For example, the power transformer used to drive the transducer cannot measure the magnetic material parameters, magnetic saturation flux density (Bs), magnetic induction (Bm), effective permeability (Ue), residual flux density (Br), Coercivity (A / M), loss factor (tan £), temperature coefficient (au / K & mdash; 1), the winding process is quite stressful, including the vacuum immersion epoxy tree. These test equipment and production environment home-based factories cannot do this. Therefore, when buying ultrasound, it is best to first understand the company's situation, do not blindly listen to the sales staff touted, and do not only look at the price. Only in this way can we reduce unnecessary troubles in the future.
6) Misunderstanding of the structure of the welding mold
There are many types of ultrasonic molds (HORN). The shape of the workpiece determines the shape of the mold. However, the size, curvature and material of each part must be strictly calculated. Some people mistakenly think that it is just a metal block. Whether the design is reasonable or not directly affects the efficiency, life, product qualification rate of the mold, and directly burns the generator when it is serious. The material of the mold is generally magnesium magnesium 7075, and some people use low-quality materials, or counterfeit 7075 to reduce costs. Regular mold manufacturers have a set of strict inspection procedures for feeding, and the processing dimensions are processed by computer software simulation and verification. Quality is guaranteed. These processes are generally not possible in the workshop. For example, if the mold is not properly designed, the reaction problem is not obvious when welding small workpieces. When there is high power, various drawbacks will occur. In severe cases, the power components are directly damaged.