Today, welding of quartz glass is mainly carried out with gas torches and by hand. The use of gas torches means that a lot of energy gets lost in the actual process zone. In addition, the manual process can result in inhomogeneous weld seams.

An automated laser process would make the quartz glass welding process more energy efficient and more repeatable. In this study, quartz glass plates up to 4.5 mm in thickness are welded together at an angle of 125° using filler materials. The purpose is to achieve a homogeneous weld (V-seam) with as few defects as possible using a lateral fiber or rod based deposition welding process.

The main challenge is to get the melt to the contact point of the two glasses so that no air inclusions occur. A 400 µm fiber and a 1 mm rod are investigated as additional materials. The advantage of the fiber compared to the rod is that the lower area (contact point of the glasses) is easier to reach during the welding process. The disadvantage is that a very high fiber feed rate is required to fill the gap. This leads to a high consumption of filler material. Process parameters include the substrate to fiber feed ratio, laser power, spot diameter, and process gas pressure and angle. The samples are analyzed using an optical microscope and a laser confocal microscope. Preliminary studies have shown that comparable results can be achieved with both filler materials.