In recent years, with the continuous upgrading of technology, lazer welding of plastics will gradually show a growing trend in the future. In the past few years, some lazer technologies have not broken through, and the lazer price is relatively high. Compared with traditional welding, the one-time investment is large, which may not produce benefits quickly. But now the economic advantage of lazer is highlighted. The lazer welding of plastic can reduce the difficulty for designers to design products.

At present, many products (including automobile semiconductor industry, pharmaceutical and food industry, etc.) have very high requirements for processing accuracy and aesthetic appearance, which makes lazer welding become a necessary process for the production of these products and promotes the further development of lazer welding technology.

The closer the compatibility, fusion temperature and matching of plastic lazer welding are, the better its effect will be. The application mode of plastic lazer welding is different from that of metal welding, including sequential circumferential welding, quasi synchronous welding, synchronous welding and irradiation mask welding. Olay Optoelectronics will briefly introduce these welding modes.

1. Profile welding

The laser moves along the contour line of the plastic welding layer and melts it to gradually bond the plastic layers together; Or move the sandwich along the fixed laser beam to achieve the purpose of welding.

In practical applications, contour welding has high requirements for the quality of injection molded parts, especially for the application of complex welding lines such as oil-gas separators. In the process of plastic laser welding, contour welding can achieve a certain penetration of the welding line, but this penetration is small and uncontrollable, which requires that the deformation of the injection molding parts should not be too large.

2. Synchronous welding

The laser beam from multiple diode lasers is shaped by optical elements. The laser beam is guided along the contour line of the welding layer and generates heat at the weld seam, so that the entire contour line is melted and bonded together at the same time.

Synchronous welding is mainly used in automobile lamps and medical industry. Synchronous welding is a multi beam, optical shaping shows the light spot of welding track, which is characterized by reducing internal stress. Because the requirements are relatively high and the overall price is relatively high, it is widely used in medical treatment.

3. Scanning welding

Scanning welding is also called quasi synchronous welding. Scanning welding technology combines the above two welding technologies, namely, sequential circumferential welding and synchronous welding. The reflector is used to generate a high speed laser beam with a speed of 10 m/s, which moves along the part to be welded, making the whole welding part gradually heat up and fuse together.

Quasi synchronous welding is the most widely used. In the auto parts industry, it uses the XY high-frequency galvanometer inside. Its core is to control the plastic welding collapse of two materials. Contour welding will produce large internal stress, which will affect the sealing of objects. Quasi synchronization is a high-speed scanning mode, and with the current control, it can effectively eliminate internal stress.

4. Rolling welding

Rolling welding is an innovative laser plastic welding process, which has many different forms. There are two main types of rolling welding:

The first is Globo ball welding. There is an air cushion glass ball at the end of the laser lens, which can focus the laser and clamp the plastic parts. In the welding process, Globo lens is driven by the motion platform to complete the welding by rolling along the welding line. The whole process is as simple as writing with a ballpoint pen. Globo welding process does not require complex upper fixture, and only needs to produce a bottom mold support product. Globo ball welding process also has a variant roller roller welding process. The difference is that the glass ball at the end of the lens is changed into a cylindrical glass barrel to obtain a wider laser segment. Roller roller welding is suitable for wider welding.

The second is TwinWeld welding process. This plastic laser welding process adds a metal roller to the end of the lens. During the welding process, the roller presses the edge of the welding line for welding. The advantage of this plastic laser welding process is that the metal pressing wheel will not be worn, which is conducive to large-scale production. However, the pressure of the pressure roller acts on the edge of the welding line, which is easy to generate torque and form various welding defects. At the same time, because the lens structure is relatively complex, it is difficult for welding programming.

4. Rolling welding

Rolling welding is an innovative laser plastic welding process, which has many different forms. There are two main types of rolling welding:

The first is Globo ball welding. There is an air cushion glass ball at the end of the laser lens, which can focus the laser and clamp the plastic parts. In the welding process, Globo lens is driven by the motion platform to complete the welding by rolling along the welding line. The whole process is as simple as writing with a ballpoint pen. Globo welding process does not require complex upper fixture, and only needs to produce a bottom mold support product. Globo ball welding process also has a variant roller roller welding process. The difference is that the glass ball at the end of the lens is changed into a cylindrical glass barrel to obtain a wider laser segment. Roller roller welding is suitable for wider welding.

The second is TwinWeld welding process. This plastic laser welding process adds a metal roller to the end of the lens. During the welding process, the roller presses the edge of the welding line for welding. The advantage of this plastic laser welding process is that the metal pressing wheel will not be worn, which is conducive to large-scale production. However, the pressure of the pressure roller acts on the edge of the welding line, which is easy to generate torque and form various welding defects. At the same time, because the lens structure is relatively complex, it is difficult for welding programming.

source: https://www.men-machine.com/news/introduction-of-five-laser-welding-methods-of-plastic/

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