Glas-L-PA

Laser-Powder-Deposition-Welding of glass

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Development goal

The conventional, manual processing of glass into complex components involves multiple stages, characterized by mechanical, abrasive processes or forming, joining, or layer melting using a gas flame. The use of flexible, automatable, and efficient processes for manufacturing individual components from glass powder is also becoming increasingly important in the glass industry. The production of a component shape using additive manufacturing processes involving laser beams directly from pure glass powder represents an attractive option for meeting these requirements. Compared to powder bed-based additive manufacturing (PBF), laser powder deposition (L-PA) offers good conditions for flexible, efficient, automatable, and direct 3D manufacturing of complex geometries. This can be done on existing semi-finished products such as plates, rods, or tubes, or on 3D surfaces such as molded bodies or functional components that have been manufactured using conventional or additive manufacturing methods. The research project investigated process strategies for laser powder deposition welding for the manufacture of application-specific glass components. Process strategies had to be developed to generate optically transparent, compact glass components (e.g., preforms for special glass fibers, filigree burner nozzles, application-specific profiles, threads) depending on the type of glass and to determine the process efficiency.

Advantages and solutions

Glass powder made from quartz or borosilicate glass can be melted onto semi-finished glass products using layer-by-layer powder deposition welding with CO₂ laser beams due to its good absorption of the 10.6 µm wavelength. Various experimental system techniques have been developed that are suitable for the automated melting of glass powder on round and flat material. These include – Powder handling, powder conveyance, and powder feed (disc conveyors and nozzle arrangements: single nozzle, double nozzle, laser head with 6 powder nozzles) – Application-dependent optical laser beam shaping and laser beam guidance (step mirror for round material, laser head with ring-shaped nozzles for flat glass) – Pyrometer-controlled process control for targeted and parameterized control of the process depending on the type of glass – Integration of a camera for optical process observation Using the developed system technology, parameter investigations were carried out on round and flat material (SiO2, B33) and significant parameter dependencies were identified. These investigations were accompanied by a materials analysis of the various glass powders. It was found that Gaussian particle distributions with a particle size D90 of 250 to 300 µm are very well suited for homogeneous powder conveying and layer melting of the glass powder. This means that glass powder, with its characteristic broken grains, has the necessary flowability in the conveying process. Furthermore, the processing temperatures of the various glass powders were determined for process control and applied in the experiments. In general, the process investigations for round material (glass rods and tubes) proved to be very promising, as they enable very homogeneous laser and process control with optimal heat management for rotationally symmetrical glass samples. This resulted in stress-minimized test specimens and demonstrators that were stress-free thanks to fine thermal cooling. 

Target market

Process and system development offers the glass industry entry into a new manufacturing technology: additive manufacturing of glass. L-PA offers an interesting, automatable option, particularly for compact glass components that are manufactured in several complex process steps, and will form the basis for AI tasks in the future. Since there are currently no types of equipment on the market that are comprehensively designed for the challenge of glass powder processing via L-PA, manufacturers of laser equipment, automation technology, and general mechanical engineering are benefiting from the developments in the project. Specific applications for component manufacturing using L-PA of glass materials are possible for application-specific profiles, threads, thick-walled tubes, rods, or various flat geometries on plates. The high flexibility of the process development allows for a wide range of products in terms of component geometry for glass products. This enables a quick and flexible response to customer needs.