Curved tempered glass is produced by heating float glass to its softening range, forming it to the required curvature, and then cooling it rapidly and evenly in specialised equipment. The result combines a shaped glass surface with the compressive-stress structure of tempered safety glass.
Forming and tempering
The glass is shaped while hot, so its curvature must be established as part of the production process. Rapid cooling then creates surface compression and internal tensile stress. When the finished pane is loaded, the surface compression is overcome first, improving its load-bearing and impact performance compared with ordinary annealed glass.
This treatment changes the internal stress distribution rather than hardening the surface. Tempering therefore does not provide a significant improvement in scratch or abrasion resistance. As with other tempered products, cutting, drilling, edgework and other fabrication must be completed before the final heat-treatment cycle.
Performance
Tempered glass provides three to five times the bending strength and five to ten times the impact strength of ordinary glass of the same thickness. Resistance to rapid temperature change is around two to three times that of ordinary glass, with the ability to withstand a temperature difference above 150°C.
If breakage occurs under an extreme impact, the pane fragments into many small particles without sharp edges rather than large shards. This breakage behaviour supports its use as safety glazing.
Design coordination
Curved tempered glass is suited to architectural designs that require both curvature and the strength and breakage characteristics of tempered glass. Accurate geometry is essential: radius, dimensions, edgework, holes and support details need to be agreed before production because the pane cannot be reworked after tempering. Final selection should also account for the visual effects and tolerances associated with curved, heat-treated glass.