Laser technology is attractive to the combining process of panels, films, molded thermoplastics, and textiles, whose property can carry the laser energy to the right point at the right time.

Interaction Between Lasers and Plastics

The effect of laser welding is decided by the wavelength which defines the way in which the plastic gains energy.

The commonest type of laser welding is transmission, whose laser wavelength is between 750nm and 1500nm. The energy absorption is, to a great extent, affected by the aids added in plastics, as well as whether the plastic is semi-crystal or non-crystal (amorphous). With the help of pigment and stuff, especially pigment like carbon black, the absorption rate of lasers can be obviously increased.

Transmission Laser Welding Cases

In 1985, the first case of transmission laser welding was applied between the upper layer of IR transmissible plastics and the lower layer of carbon black stuffed components. The carbon was heated by absorbing the laser energy and the welding is completed on the interface of both sides. It is the commonest welding method although the components must be black. The black surface, like a heating element, absorbs the most quantity of heat, provides its neighbor parts from heat damage, and does its best to remit deformation and pollution of the connecting point.

As time went by, in the year 1998, a substituent energy absorber came out and broke the color limitation (the color in the connecting part was, from then on, no longer to be necessarily black). Nowadays, plastic components with almost all colors are available for transmission laser welding, whose application includes:

Medical apparatus and instruments


Car parts


In recent years, this technology is introduced to the production of fiber reinforced thermoplastic composites. Heated by the laser, the composite plastic is fused while the reinforcement fiber remains unaffected.

Transmission laser welding can be used in glass fiber and polymer fiber reinforced composites and other materials with less stuff. If the plastic material is black or reinforced by carbon fiber, or with high stuff content, it’s better to use direct laser welding.


In TOPOLO, we provide PP and PA6 UD tapes made of fiber reinforced thermoplastic composites. Carbon black is contained in both series tapes and evenly distributed. They are suitable for laser welding.

Our CFRT products can be widely used in transportation, construction and packaging industry, especially in automobiles, for lightweight and high strength. Please feel free to contact us for more ideas.