Apr 16, 2020
Laser welding technology can be used in almost all thermoplastic and thermoplastic elastomers. Commonly used welding materials are PP, PS, PC, ABS, polyamide, PMMA, POM, pet, and PBT. However, some other engineering plastics, due to their low laser transmittance, can not directly use laser welding technology. Generally, carbon black is added to the bottom material, so that the material can absorb enough energy, so as to meet the requirements of laser transmission welding. Laser welding of plastics is related to the improvement of material requirements, which are often difficult to achieve. The so-called laser transmission welding requires laser radiation to penetrate the parts on the one hand, and on the other hand, the parts have strong absorption performance. It is important to avoid cracks between the two weldments. In the process of laser welding, the absorbent parts are heated and melted locally, and the energy is transferred to the transparent parts through heat conduction. Under external pressure, the two parts are combined. The absorbed near-infrared laser is converted into heat energy, which melts the contact surface of the two parts and finally forms the welding area. This welding method can form a welding seam that exceeds the strength of the raw material.
At present, the plastic welding technology commonly used in laser welding machine mainly includes vibration friction welding, hot plate plastic welding, and ultrasonic welding, which are mainly used to connect sensitive plastic products (including circuit board), plastic parts with complex geometry and plastic products (medical equipment) with strict cleaning requirements. The advantages of laser welding of plastic parts are: the size of the welding seam is precise, airtight and watertight; the welding is firm, and the weldment with high precision can be obtained. In the process of welding, the resin degradation is less, the debris is less, there is no flash, and the surface of components can be connected precisely; the welding equipment does not need to contact with the bonded plastic parts, compared with other welding methods, the vibration stress and thermal stress of the products are greatly reduced; the thermal damage and thermal deformation are minimized, and the resins of different components or different colors can be bonded together; and For the parts with small welding size or complex shape and structure, some complex parts can even be "through welded"; the vibration-free technology can produce airtight or vacuum sealing structure; it can weld a variety of different plastics, while other welding methods have greater limitations; the equipment has a high degree of automation and can be easily used for the processing of complex plastic parts. Be good at welding products with complex shapes (even three-dimensional); be able to weld areas that are not easy to reach by other methods. Because laser welding has the above advantages, it is particularly attractive to processors seeking cleaner ways to weld complex components, such as plastic products containing circuit boards, medical equipment, etc.
Laser welding technology is to melt the plastic in the joint area with the concentrated strong radiation wave which usually exists in the infrared area of the electromagnetic spectrum. The type of laser used and the absorption characteristics of the plastic determine the degree of welding. Laser welding also greatly reduces the vibration stress and thermal stress of the products. The vibration stress and thermal stress produced by other connection methods are smaller, which means that the aging rate of internal components of products or devices is slower. This provides an opportunity for laser welding to be applied to easily damaged products such as electronic sensors.