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Various laser welding methods for plastics
Publisher: suzhou kailinneng automation equipment co., LTD Release time：2023-03-23 15:08:12 Click on the number of times：68 Shut down
Various laser welding methods for plastics
(a) Profile welding
In the welding zone of laser transmission welding, contour welding is the most flexible, simple and popular technology. During the process, the laser beam is focused to a point in the welding zone and moves along the contour, as shown in Figure 1(a). The movement of the beam can be controlled by computer software on which the weldment is secured, or by a robotic arm carrying the fixed welds. The use of robots has greatly broadened the application range of contour welding and raised it to compete with ultrasonic welding and vibration welding. The advantage of this method lies in its substantial "flexibility", the possibility of programmable random trajectory of the robot, and the control of the diameter of the weld by changing the focal length.
(b) Synchronous welding
During the machining process, both the welding element and the laser beam remain stationary. First, the laser head is customized according to the welding area, and the laser is emitted by multiple diode laser beams at the same time on the contour line to melt the welding area, so as to weld the materials together, as shown in Figure 2(b). The disadvantage of synchronous welding is that the device used is complex, and its lens must be specially customized according to the shape of the welding area. Therefore, the cost is high, and it is usually used for mass welding of large parts.
(c) quasi-synchronous welding
Similar to contour welding and synchronous welding, a laser beam is projected onto the welding area for high-speed scanning along the contour, which can be scanned several times per second, so that the welding area is approximately heated and melted at the same time to form a weld, as shown in Figure 2(c). Therefore, welding strength and welding quality are related to laser scanning speed, scanning cycles and laser intensity. The advantages of quasi-synchronous welding are high degree of freedom, good flexibility, especially suitable for simple two-dimensional welding, such as mobile phone shell, electronic component shell, etc.
(d) Mask welding
Using a membrane that can absorb or reflect the laser, the laser beam is projected onto the welded area and causes the laser beam or weldment to move. The target welded area is not obscured by the mask and thus melts and forms a weld, as shown in Figure 2(d). Mask welding enables the formation of welds in widths exceeding 10μm. In addition, mask welding is very "flexible" as the shape of mask determines the area of welding, not only for straight welds, but also for welds with complex shapes, which can be formed by using appropriate masks. Mask welding precision can reach the micron level, and the method has been used in the welding of precision and small size components, including the medical, electronic, and electrical industries.
(e) Reflection welding
Mainly used for cylindrical surface circular line welding. After being positioned by a high-speed scanning motor, the laser beam is projected onto the welding area through secondary reflection of a conical mirror to form radial radiation on the surface of the cylindrical weldment. Contour welding or quasi-synchronous welding can be performed according to the scanning speed of the motor, as shown in Figure 2(e). Reflection welding has high yield and no clamping device. It is especially suitable for cylindrical welds with different diameters and no rotation.