Presentations

High performance coated bent tempered glass

Bent glass has a long tradition in architectural glazing. The industry provides several technologies to bend glass into curved shapes within small to large radii. These fabrication methods include slump-bending, temper-bending, warm-bending by lamination & cold bending (by force). All individual methods bear technical and aesthetical advantages as well as disadvantages towards applications in modern glass architecture. As building energy and sustainability codes are becoming more strengthened nowadays, as owners and developers are keeping a close eye on the building performance and operation cost, high performing solar control and low emissivity (low-e) coatings are on demand and almost mandatorily required in new construction and retrofit projects. However, what has become a standard in flat glass fabrication is significantly complicated and relatively new for bent glass. Slump(Hot)-bending of glass imposes a long period of heat treatment modern soft coatings are not resistant to. Warm bending may damage coatings while being in contact with bending racks. Consequently, double- or even triple-silver high performance low-e (soft-) coated glass can only reliably be curved via an online temper-bending process where glass is being heat-strengthened or fully-tempered and formed into a cylindrical shape at the same time. This process is equal to standard glass tempering, but has an adjustable and computer formable quench at the end of the tempering furnace, bending the glass into its demanded shape. The process impacts the low-e coating with high temperatures over a short-time period while condition, formulation, heat stability and formability of the coating play a major role to be controlled by furnace configurations. Furthermore, dimensional and radius limitations impact the technical feasibility as common surface distortions of tempered glass are to be controlled and avoided. Comprehensive testing and quality control has been performed to carve out a guideline including a range of coatings bendable for architectural glazing and façade purposes.