Transparent plastics are widely used in various fields. Laser welding is a high-precision and efficient connection method, and has gradually become a key technology for transparent plastic connection. However, since different types of transparent plastics have different optical and melting properties, the appropriate laser welding method needs to be selected based on the specific situation. The following are recommended laser welding methods for different types of transparent plastics:

■ Acrylic plastics (such as PMMA): For this type of plastics, continuous wave laser welding methods are usually used. This method can achieve welding by locally heating and melting the plastic surface, thereby forming a uniform and transparent welding interface. Continuous wave laser is suitable for applications requiring high welding temperatures and speeds.

■ Plastics such as polycarbonate (such as PC): When processing plastics such as polycarbonate, commonly used laser welding methods include transparent laser welding and transmission laser welding. Transparent laser welding generally uses infrared laser, which is suitable for situations where high welding depth and quality are required; while through-laser welding uses ultraviolet laser, which is suitable for thinner materials or situations where the heat-affected zone needs to be controlled.

■ Polystyrene plastics (PS, etc.): When processing this type of plastics, pulse laser welding technology is usually used. Pulse laser can provide sufficient energy in a short time to achieve local heating and melting, and is suitable for situations that require high precision in the welding area.

■ Polymethylmethacrylate plastics (such as PMMA) are usually connected using plasma laser welding technology. This welding method uses a high-energy laser beam to quickly melt and mix materials, and is suitable for situations where high welding depth and quality requirements are required.

For different types of transparent plastics, it is necessary to choose the appropriate laser welding method according to their characteristics and needs. During the laser welding process, the transparency of transparent plastics will be affected to a certain extent, depending on the laser welding conditions and material characteristics.

How to improve the welding efficiency of laser welding of transparent plastics? (figure 1)
           

During laser welding, the laser beam is absorbed by the plastic and partially heated, causing the plastic within the welding area to melt and join. This process causes the plastic around the welded joint to melt and deform to a certain extent, affecting its optical properties, including transparency.

The factors that affect the transparency of transparent plastics include the following:

1. If the welding temperature is too high, it may cause excessive melting of the plastic part, causing bubbles, scorching or color spots, thereby affecting the transparency.

2. Excessive welding speed will cause the plastic in the welding area to fail to fully melt and combine, leaving opaque material at the joint, thus affecting its transparency.

3. The relationship between laser power and focal spot size: Too high laser power or too large focal spot will cause excessive heating of the welding area, causing excessive melting of the plastic and affecting transparency. Requires careful control.

4. Material selection: Different types of transparent plastics have different optical properties and melting properties. Choosing the right material also affects the transparency after laser welding.

In order to maintain the transparency of transparent plastics, the parameters must be controlled during laser welding to ensure that the plastic is heated evenly during welding and that the welding area is properly melted and bonded. At the same time, the transparency of welded joints can be improved through post-processing methods such as surface polishing and heat treatment.

When welding transparent plastics, quality issues such as cracks, melt marks, or color differences may occur, depending on a variety of factors, such as welding parameters, material properties, and operating techniques.

How to improve the welding efficiency of laser welding of transparent plastics? (figure 2)
                   

5. Cracks: If the temperature during the welding process is too high or the welding speed is too fast, it will cause the plastic part to overheat and cause cracks. In addition, material selection and pretreatment can also affect the occurrence of cracks. To avoid cracks, it is necessary to strictly control the welding temperature and speed, select appropriate welding parameters, and ensure material quality and surface smoothness.

6. Melt marks: During plastic welding, the material is heated to the melting point and becomes liquid, which may produce melt marks near the welded joint. Such marks are usually caused by uneven temperature distribution or overheating of the welding area. To avoid traces of melting, welding temperature and energy distribution need to be precisely controlled to ensure uniform temperature in the welding area.

7. Color difference: During welding, some plastics will be locally heated and melted, causing the color of the welding area to change, resulting in color differences. This difference may be caused by plastic breakdown, oxidation, or other chemical reactions. In order to reduce the occurrence of color differences, it is necessary to accurately control welding parameters, avoid excessive heating and oxidation, and select appropriate welding conditions and material pretreatment methods.

Transparent plastic joints typically maintain long-term stability and durability when laser welded. However, the long-term performance of a joint can be affected by a variety of factors, including material selection, weld quality, environmental conditions and subsequent use. Therefore, in order to ensure that the transparent plastic joints after laser welding can maintain long-term stability and durability, it is necessary to comprehensively consider material selection, welding quality, environmental conditions and subsequent use, and take corresponding measures to protect and maintain the joints.

As a professional manufacturer in the field of laser welding, Lesser Laser is committed to providing customers with high-quality laser welding solutions. We can provide customized welding solutions according to customer needs and ensure welding quality and stability.