The principle of plastic laser welding technology

Plastic laser welding uses the principle of transmission welding. Infrared laser is generally used as the welding heat source since the laser in the 800nm-1100nm band has a low absorption rate for most types of transparent or colored thermoplastics, and the laser loses less energy through the plastic.

Transmission welding generally uses lap joints and is fixed by a clamp that can provide a certain clamping force. And the upper and lower layers of materials must meet certain requirements. The upper layer of material needs to be able to transmit the laser to the greatest extent, and the lower layer of material needs to be able to absorb the laser to the greatest extent.

The laser shines through the upper material to the surface of the lower material. Since the lower material has a higher absorption rate for the laser, the laser is absorbed at the joint surface and generates a large amount of heat. At the same time, the heat is transferred from the lower material to the upper material through thermal conduction, so that The plastic melts at the joint surface and polymerizes for a second time under the action of clamping force. After cooling, a weld is formed at the joint surface, that is, welded together.

Plastic laser welding advantages:

1.The welds are precise and strong, airtight and watertight, and have good sealing performance;

2.No residue is generated, so the welding parts can be welded together tightly;

3.As a non-contact welding, there is no damage to the surface of the weldment;

4.It has flexible controllability, controls laser and fiber output laser through computer software, and can weld products with small size or complex shape (even three-dimensional);

5.It greatly reduces the vibration stress and thermal stress generated by the product during the welding process, can be used for welding of easily damaged products, and can extend the service life of the product;

6.Many different types of plastic materials can be welded together, such as PC and PBT doped with 30% glass fiber;

7.The equipment is small in size, easy to operate, low in cost and easy to maintain.

Application of plastic laser welding in automotive parts

In order to improve the efficiency of automobile engines, one way is to reduce the weight of the automobile body as much as possible. Plastics, resins, special glass and other materials are increasingly used in automobile parts due to their light weight, corrosion resistance, and good stability.

The traditional automobile engine intake manifold material is cast aluminum. Since the 1980s, plastic engine intake manifolds have been widely used in the manufacture of intake manifolds instead of cast aluminum due to their smooth walls, high efficiency, and light weight. The use of laser welding can not only produce intake manifolds with more complex structures and shapes, but also has good welding quality, high strength, small residual stress, no welding slag, and easy automated production. Therefore, laser welding technology has gradually become an important welding method for manifold manufacturing.

The appearance design of automobiles has received more and more attention recent years. As an important functional component of automobiles, the manufacturing process of taillights has become increasingly important. Below picture shows the use of laser welding technology to weld car lights. There is no need to change the color of the transparent material, and it has good sealing, no water leakage or air leakage, and the weld connection has high strength and beautiful appearance.

The gas-liquid separator is one of the important components of the automobile fuel tank system. It is mainly composed of an injection-molded POM upper cover and shell. The product is packaged through laser welding, with high process stability and high welding strength. For the car dashboard shell, it not only requires a beautiful appearance, but also has strict requirements for sealing and corrosion resistance. The instrument panel welded by plastic laser welding technology has good weld sealing and high connection strength.

Others include automobile electronic door openers, gearboxes, airbags, oil pressure sensors and engine sensors, among which plastic laser welding technology is also widely used.