Laser welding of glass is ready for industrial practice

TRUMPF has developed a femtosecond laser system for welding glass, replacing conventional joining processes such as gluing.

TRUMPF (Ditzingen, Germany) has developed a femtosecond laser system for welding glass that replaces conventional joining processes such as gluing. In contrast to gluing processes, no additional materials that are susceptible to evaporation or embrittlement are required, reducing costs and increasing durability as well as the stability of the seam. Glass is hard and brittle, has lower thermal conductivity than metal, and tends to crack when heated unevenly, but femtosecond laser systems can prevent such cracking.

Glass is permeable to light with wavelengths ranging from ultraviolet to near-infrared. Absorption takes place only when the energy densities are very high, so that processing within the glass is facilitated. The highest performance density lies deep in the lower glass at the focal point. The energy from several thousand laser beam pulses causes a melt pool to be created and pushed upwards in just a few milliseconds. Skillful thermal management and an optimal ratio of pulses and pauses prevent the glass from cracking.

Glass components that were previously glued to each other can now be economically welded with high-quality results, as the company has demonstrated in its own production of laser light cables. Until recently, the lids of the protective caps for light cables were glued on—now, lasers are used to weld them on. The joint strength of the glass parts depends primarily on the level of pulse energy.

The company is currently building a laser welding system for reliable glass welding for mass production of the protective caps for the laser light cables in its own production plant in Schramberg, Germany.

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