In the actual production process of ultrasonic welding, not all ultrasonic plastic materials can be welded with an ultrasonic plastic welding machine. Ultrasonic welded plastics are thermoplastics. Only when the molecular structure is the same or similar, ultrasonic welding can be carried out. On the welding surface, there is a chemical bond between molecules, so the closer the base material is. The ultrasonic welding effect is better. Today, we will analyze and explain some common plastic welding compatibility comparisons, as follows:
At present, most of the commonly used injection molding polymers can be welded by ultrasonic, but the difficulty of welding plastics with ultrasonic plastic welders is related to many characteristics of the welding itself. The greater the coefficient of friction of the plastic, the worse the thermal conductivity, the easier it is for the interface to form a molten layer, the better the ultrasonic welding performance, and the harder the plastic. In plane welding, because the vibration transmission loss is small, the ultrasonic welding is lighter. Since crystalline plastics have a narrow temperature range from solid to molten state, and the speed is very fast, the welding machine may have poor performance and very difficult to adjust.
In the process of riveting and welding, the ultrasonic welding function of soft plastic is easier than that of hard functional plastic. At present, various plastic products emerge in endlessly. The ultrasonic plastic welding function of several commonly used plastics is briefly introduced.
(1) PCPSU: The material has a high melting point and strong moisture absorption. It should be dried before welding, otherwise the moisture in the material will hinder the welding strength, and the moisture will increase the welding energy consumption and extend the welding time.
(2) Molten polyvinyl chloride (PVC): It is a low-melting, soft material with large ultrasonic energy loss. During the welding process, the surface of the weldment is easy to burn.
(3) abs.hips.pmma.mppo: Amorphous steel material, easy to conduct the ultrasonic frequency of 20000hz, especially suitable for ultrasonic welding, no matter long distance or short distance can achieve good welding effect;
(4) Welding plastic PP.PE: It is a crystalline material. Ultrasonic waves will produce large losses in the propagation process, and it is difficult to weld long distances.
(5) Welding plastic PA: strong crystallinity, strong hygroscopicity. It should be dried before welding.
In order to obtain a better welding effect, it is also necessary to consider the factors that affect the welding quality. During the welding process, pressure, time and heat absorption (melting amount) are the three factors that guarantee the welding quality.
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