Glas_SLM

Additive manufacturing of transparent glass components

Development goal

Additive manufacturing processes for silicate materials are currently still being researched or in the industrial introduction phase and require extensive system technology and process steps. This usually results in glass objects or glass preforms with no or limited optical transparency. The project involved developing a partially automated system technology for the selective laser melting (PBF-LB) of quartz glass powder. Process parameters and process strategies were to be developed in order to generate optically transparent, compact glass components from the powder bed.

Due to the good absorption of the wavelength of 10.6 µm in the glass, a CO₂ laser was selected for layer-by-layer melting as well as for subsequent contour post-processing. The development objectives were as follows: 1. development and design of the process technology for the melting process 2. development of contour post-processing by changing the laser beam focusing for the melting and contouring process steps 3. investigation of the material-dependent laser and process parameters and geometric possibilities 4. material characterization of the glass powders and component quality as well as evaluation of the overall process.

Advantages and solutions

As a result of the developments, a functional beam melting system with the typical system components for glass powder was built, which enables glass-compliant and contamination-free glass body production:

POWDER HANDLING UNIT: Hopper for powder intake, coater with fiber brushes, building platform with glass inserts, inductive heating for stress relief of built glass body, plastic container for residual powder

LASER UNIT: CO₂ laser beam source, telescopic optics for laser beam focusing (melting in cw mode and contouring in pulse mode), laser scanner for beam deflection

CONTROL UNIT: electrics, pneumatics, mechanics, temperature measurement technology, program flow chart for automated process control for the cycle operation of the PBF-LB process of glass powder

Furthermore, optimum process parameters for optically transparent melting of the SiO₂ powder particles were determined, various sample bodies were constructed and process parameter limits were determined. In particular, the innovation of the laser-based powder bed fusion process for the production of transparent quartz glass components lies in the use of a defocused laser beam for melting the glass powder layer by layer and a focused laser beam for contour processing during the process.

The focused, pulsed laser beam has a higher peak pulse power and adhering particles in the edge area of the melted component are removed.

Target market

The potential for the production of transparent glass components from the powder bed was demonstrated in the project. The technology developed represents a supplement to existing production processes for the glass industry and offers an opportunity to develop new products and technologies. The process is particularly interesting for the production of prototypes and lightweight structures made of glass. The project belongs to the special glass and technical glass sector, which manufactures and supplies components and systems for the electrical industry (e.g. chip, wafer, semiconductor production), precision mechanics and optics, plant engineering, communications, chemical and environmental technology (glass apparatus construction).

Glass currently plays a key role in many high-tech applications and is increasingly developing into a trend material as a sustainable growth driver to replace plastics. The technological shaping processes for manufacturing glass products require high temperatures, depending on the type of glass, and are therefore among the most energy-intensive industries in Germany and Europe. The laser as a tool is already helping to increase efficiency and conserve resources in many production processes. With the results of this project, a new way to achieve further energy savings in the glass industry and increase the quality of glass prototypes can be demonstrated, particularly through the use of optical technologies. Automation solutions