Article on the portal strojirenstvi.cz about laser welding

As a method of permanently joining plastic parts, plastic welding is a frequently used industrial method. Although welding of plastic components is carried out using several types of methods, laser welding is increasingly being used.

With a laser system from LINTECH, it is possible to create a very flexible, fast and reliable process whose limitations are far outweighed by the benefits provided. Solid-state lasers with wavelengths in the near-infrared spectrum are used, e.g. diode lasers and very often also fibre lasers. As plastics have a low melting temperature and poor thermal conductivity, lasers with powers up to 300 W are sufficient for the application, in some cases even lasers with powers of only a few tens of watts can be used successfully.

Transmissive method

Most often, the so-called transmissive method is used in welding, when one plastic is “overlapped” by another (the plastics lie on top of each other, the upper piece overlaps the lower one). The top plastic transmits the laser radiation to the bottom layer and there, at the junction of the two materials, the beam is absorbed. The heat input melts the lower layer, then, after conduction, the upper layer, and under pressure the melts are mixed, leading to the welding of the parts.

Variability of welding equipment

Depending on part shapes and other application requirements, LINTECH welding equipment can take many forms. When welding smaller parts, a more space-saving solution is used, using a laser deflection head that sweeps the laser beam at high speed and often repeatedly across the material surface at the weld contour (the so-called quasi-simultaneous method). If the parts to be welded are larger or more complex and the deflection head optics can no longer accommodate them, a robotic arm with a technological laser head is used for the process.